CHEMISTRY

PRACTICAL

1989 – 2020

• PRACTICAL QUESTIONS
• COORDINATED MARK SCHEMES
• PREPARATION AND CONFIDENTIAL INSTRUCTIONS

Table of Contents

LEAD NOTES QUANTITATIVE AND QUALITATIVE ANALYSIS

QUALITATIVE ANALYSIS

IDENTIFICATION OF IONS

• Addition of Sodium hydroxide
• Addition of aqueous ammonia
• Addition of dilute hydrochloric acid or sodium chloride
• Addition of dilute Sulphuric acid or Sodium sulphate
• Flame test
• Action of heat
• Oxidising and Reducing agents

ALSO READ; CHEMISTRY PRACTICALS GUIDE

QUANTITATIVE ANALYSIS

SETTING TRENDS TABLE

Year and Question No.( )
The mole: Formulae and chemical equations TESTED in all years EXCEPT 2002
Acids,    Bases             and salts	90 (c)	06 (1)	09 (1)
Energy changes in chemical and physical processes	89 (III)	94(1)	95(1)	97(1)	00 (2)	01(III)	03 (2)
	04 (1)	05(1)	07 (1)	08 (1)	10 (1)	13(1)
Reaction rates and reversible reactions	92 (1)	99 (1)	02 (1)	12(1)

 

Questions

Mark schemes

Practical Requirements

Practical Experience 1989	15	–	113
Practical Experience 1990	17	–	114
Practical Experience 1991	–	–	–
Practical Experience 1992	20	–	115
Practical Experience 1993	23	–	116
Practical Experience 1994	25	–	117
Practical Experience 1995	28	75	118
Practical Experience 1996	32	77	118
Practical Experience 1997	35	80	119
Practical Experience 1998	38	82	120
Practical Experience 1999	41	83	121
Practical Experience 2000	43	85	122
Practical Experience 2001	46	87	123
Practical Experience 2002	49	89	124
Practical Experience 2003	51	90	125
Practical Experience 2004	57	–	126
Practical Experience 2005	58	92	127
Practical Experience 2006	60	93	128
Practical Experience 2007	63	99	129
Practical Experience 2008	66	105	130
Practical Experience 2009	69	102	131
Practical Experience 2010	75	107	132
Practical Experience 2011	81	115	142
Practical Experience 2012	87	118	143
Practical Experience 2013     Introduction	87	125	144

 

The main aim of Chemistry Practical examination is to test a candidates ability to: a).   Follow instructions

• Handle apparatus and chemicals
• Make accurate observations and deductions/inferences

This book contains 26 practical examinations from 1989 – 2013 as they appeared in during the respective examinations periods. The requirements and preparation procedures for each practical has been provided.

The teacher should give minimal assistance to candidates when carrying experiments to build confidence and enable them make their own observations and inferences. Confidence is only built with constant practice. Candidates are also advised to write the observations as they ‘observe’ during the practical but not the literature they have read from the books.

In experiments involving quantitative analysis the readings show slight variations from the ones given in the answer scheme and also from region to region. Therefore in the calculations and plotting of graphs, the teachers are required to use their school values. Teachers are advised to use the scheme as a guide not as the final correct answer.

QUANTITATIVE AND QUALITATIVE ANALYSIS

The chemistry practical mainly tests the candidates on two parts. Qualitative analysis and quantitative analysis. Students should be exposed to various types of experiments during teaching. Where it is not possible to carry out experiments individually, a well designed demonstration should be undertaken. Teachers should avoid theoretical teaching as this has been manifested many times during the marking of this paper.

Language used to communicate the observations and results must be checked after each practical experiment. Discussion of the results and clear explanations should be given after every experiment. Apparatus must be cleaned to avoid contamination and must be assembled correctly if accurate observations are to be obtained.

Introduction to Quantitative Analysis

Quantitative analysis in chemistry practical examination mainly involves the volumetric analysis. Volumetric analysis is a means of estimating quantities of certain substances (often acids or alkalis) by an analytical process which involves measurement of volumes of liquids using pipettes, burettes and measuring cylinders. Weighing is also involved. It involves the use of the following apparatus

• Thermometer
• Stop-watch/stop-clock
• Other common apparatus found in a laboratory

In the K.C.S.E Chemistry practical examination this section requires the candidate to carry out an experiment, record and interpret the data. The interpretation involves calculations and drawing graphs after a candidate has collected the data.

A candidate who is not sure with the calculations after collecting the data is advised to record all his data in the table (s) provided and finally do the calculations. About half of the total marks awarded in this section is mainly from the recording of the data.

It is important for the candidate to spend sometime reading the instructions and the procedure to ensure that all the apparatus and reagents are present and the procedure is clear. After that, the candidate can start going through the procedure step by step and recording the data

 

In the procedure the key words are normally written in bold letters so that the candidate does not make any mistake.

 

The common areas in chemistry tested in this section of the practical examination are; a).    Moles and molar solution

• Titration i).       Acid-base titration

ii).      Redox titration iii).      Back titration

• Solubility and drawing solubility curves
• Determining melting, freezing, and boiling points
• Molar heats of reaction e.g. solution, displacement, precipitation,, neutralization and Hess’s law
• Rates of reactions and reversible reactions

 

Possible errors made in quantitative analysis

1. Errors made when weighing the substance by the Technician or teacher
2. Contaminated solutions  due  to  use  of  apparatus,  which  are  not  clean.  All apparatus  e.g.  burettes,  measuring  cylinders,  beakers  etc  should  be  rinsed thoroughly before using them and after use
3. Candidates not able to read the stop- watch or thermometers properly when taking measurement of time and temperature respectively
4. Candidates not able to identity the end – point accurately during titrations

 

Interpretation of data and calculations

To score maximum marks, candidates are required to be perfect in drawing of graphs The mole concept is important to all the calculations involved in the practical examination.

 

As observed earlier (from the trends table) the topic on energy changes is not properly understood. Questions on energy changes are repeated yearly. More time should be allocated to its teaching and students allowed to carry out experiments on heat changes. Heats of displacement, solution are quite easy to determine. Students should be allowed to determine them. More examples on calculations involving energy changes should be given to students for practice.

Introduction to Qualitative Analysis

3

This involves the identification of various ions in a substance. The tests in this section have been kept as simple as possible to enable the learner understand he/she is doing. To avoid these complex reacts the scheme has been restricted to the detection of the following ions;

4

NH ⁺,  K⁺,  NA⁺,  LI⁺,  Ca²⁺, Ba²⁺,  Al³⁺, Zn²⁺, Fe²⁺, Fe^+3,

Pb²⁺,Cu^2+, CO ^2-, HCO3-, SO^2-3, NO ^–, Cl^–, Br^– and I^–.

 

3

This section also tests candidates on identification of organic compounds and their characteristics. When doing the practical examination. Work systematically through the experiments, in the order they are given, writing your observations and deductions as you go along.

If you are unable to make sense of a particular reaction, leave it after recording your observations and move on to the next test or experiment. Do not waste time. You should have time at the end to go over your work, correcting mistakes and checking for anything you think you have missed. Follow the instructions and the procedure carefully.

How to make observations and deductions

Observations are changes you see when you carry out a test or experiment. Observations are;

• Colour changes
• Formation of precipitate
• Gases evolved, including colour, smell. iv). Sound, heat or light produced

 

Tests for gases

Do not waste time testing for gases unless you know a gas is being produced or unless its indicated in the instructions that test for and identify any gas being produced.

 

Gases can be detected by:

• Colour
• Effervescence (bubbling of gas) iii). Smell

iv).     Effect on moist litmus papers

Deductions/Inferences

4

Deductions are something you can say about the unknown substances. This can be: i).          Anions and cations present in the unknown substance (e.g. SO ^2-, or Fe²⁺ ions)

• the substance is an oxidizing or reducing agent
• the substance is saturated or unsaturated (incase of organic substances)

 

Deductions must be specific.

• A common mistake is to simply write; “Cu²⁺. You should write Cu²⁺ present
• Do not forget that even tests that show no precipitate formed often have a

4

deduction. For example; you might add Ba(NO3)2 solution to a solution of a substance and see no precipitate. From this you can deduce that there is no sulphate, SO ^2-, present (otherwise a white precipitate would be seen)

• Another common fault is to give the identity of gases as

Your

deduction is what type of a substance has produced the gas. For example,

 

if you add acid to a solid and observe carbon (iv) oxide then a carbonate is present.

• Deductions must be written as soon as you have recorded your
• Do not leave all the deductions until you have completed all the If you do

this, you may miss important observations and deductions in other tests, often need the deductions from earlier test to make sense of later tests.

 

Identification of cations (metallic ions)

The two common reagents used in the identification of cations are: i). Sodium hydroxide solution

ii).      Aqueous ammonia

 

However, other reagents like dilute hydrochloric acid or an aqueous solution of soluble chloride e.g. sodium chloride and dilute sulphuric acid or an aqueous solution sulphate

e.g. sodium sulphate are use to identify some cations.

 

In most cases candidates are required to prepare small quantities of solution in a boiling tube or test tube for the unknown substance. If the substance is being tested is insoluble in water, dilute hydrochloric acid is added to the substance. If the solids still will not dissolve it is probably a lead salt and dilute nitric acid must be used.

 

For the identification of ions to be done the compound must be in aqueous form. The alkali is first added drop wise while the candidate records the observation and then in excess again and observation recorded.

 

 

 

 

 

 

Addition of Sodium Hydroxide Solution to a Solution in a Test Tube

 

Test	Observation	Inference
Add a few drops of NaOH solution drop wise until in excess	a). No precipitate formed	Zn2+, Al3+, Pb2+, Mg2+, or Ca2+ absent.
	b). White precipitate , insoluble in excess of NaOH(aq)	Ca2+ or Mg2+ present
	c).  White precipitate, soluble in excess NaOH (aq) forming a colourless solution.	Pb2+,Al3+ or Zn2+ present
	d). Green precipitate which turns brown on exposure to air.	Fe2+ present

 

	e). Brown precipitate insoluble in excess NaOH(aq)	Fe3+ present
	f). A blue precipitate is formed insoluble in excess NaOH	Cu2+ ions present

 

Addition of aqueous ammonia to a salt solution in a test tube

 

Test	Observation	Inference
Add a few drops of NH3(aq) solution until in excess	a). No white precipitate formed	Ca2+ present/ Na+, K+, NH + 4
	b). White precipitate , insoluble in excess of NH3(aq)	Mg2+,Pb2+ or Al3+ present
	c).  White precipitate, soluble in excess NH3(aq).	Zn2+ present
	d). Green precipitate insoluble in excess	Fe2+ present
	e). Brown precipitate insoluble in excess	Fe3+ present
	f). Pale blue precipitate; which dissolves to form a deep-blue solution in excess NH3(aq)	Cu2+ present

 

Addition of Dilute Hydrochloric Acid or Sodium Chloride Solution

Test	Observation	Inference
Add a few drops or (a known volume) of dilute HCl or NaCl(aq) to a solution in a test tube.   ‘’     ‘’     ‘’     ‘’       ‘’	a). White precipitate formed	Pb2+, Ag2+ ionspresent.
	b). No white precipitate formed	Pb2+ and Ag+ ions absent

 

Addition of Dilute H2SO4 acid or Sodium Sulphate Solution

Test	Observation	Inference
Add a few drops or (known volume) of dilute H2SO4 or NaSO4 to a solution in a test tube.   ‘’    ‘’       ‘’     ‘’     ‘’	a). White precipitate formed	Ca2+, Pb2+ or Ba2+ present.
	b). No white precipitate formed	Ba2+, Pb2+,or Ca2+, absent

 

Identification of Cations Using the Flame Test

The presence of some metallic ions can be identified by heating the substance in a flame using a platinum wire or a glass rod

 

The Bunsen burner flame should be non-luminous for correct observation to be made

 

Test	Observation	Inference
Dip a clean platinum wire or a	a).   Lilac    or        purple	K+ present.

 

glass rod into a solution of salt	/orange flame
	b). Golden yellow flame	Na+ present
	c). Crimson flame	Li+ present
	d).Brick-red flame	Ca2+ present
	e).Green-blue flame	Cu2+ present

 

 

Identification of Anions

The substances to be identified must be in aqueous form before the reagents are added The anions are commonly identified by the use of dilute acids e.g. HCl acid. Precipitation reactions with reagents listed in the table below are used as confirmatory tests.

 

Test	Observation	Inference
1). Add dilute acid e.g. HCl to a solution in a test tube	Effervescence /bubbles of a gas are produced.	CO 2-     or     HCO – 3                                         3 SO2-3 present
2). Add barium Chloride or Barium nitrate solution to a solution in a test tube followed by dilute HCl acid	White precipitate formed which is insoluble in dilute HCl acid	SO 2- present 4
3). Add barium Chloride or Barium nitrate solution to a solution in a test tube followed by dilute nitric acid or dil. HCl respectively	White precipitate is formed which dissolves on the addition of the acid	SO 2-      or      CO 2- 3                                     3 present
4).Acid lead (II) nitrate to a solution in a test tube followed by dilute HNO3 acid	White     precipitate               formed which dissolved on boiling	Cl– present
	b).White precipitate insoluble on boiling	SO 2-      or      CO -2 4                                     3 present
	c).Pale      cream                 precipitate formed.	Br– present
	d).Yellow precipitate formed	I– present
5).Add a small quantity of cold, iron (II) sulphate solution. Gently pour concentrated H2SO4 acid down the side of the tube.	A brown ring forms in the junction of the two layers	NO – present 3
6). Add dilute acid to a substance in test tube Test with acidified KMnO4 solution or acidified K2Cr2O7	A gas with a smell of rotten egg evolved Gas blackens the lead ethanoate paper or lead (II) nitrate solution.	S2- present
7). Add dilute acid to a substance in test tube Test with acidified KMnO4 solution or acidified K2 Cr2 O7	Effervescence (bubbles of a colourless gas Pungent smell KMnO4 turn from purple to colourless	SO 2- present 3

 

K2Cr2O7 turn from orange to green

 

Action of Heat

When heating solid substances always makes sure that the test-tube is clean and dry.

 

Test	Observation	Inference
Heat a small amounts of the solid in a clean and dry test tube and test for any gas or gases evolved	a). Colourless liquid formed on cooler part or upper part of test tuber OR vapour condenses to a colourless liquid	Hydrated salt or a hydrogen -carbonate or hydroxide
	b). Colourless gas which gives a white precipitate with lime water	CO 2- /HCO–3 present 3
	c).Colourless      gas                           that relights glowing splint	Nitrate of potassium or sodium
	d).Pungent       smell;                   dark brown     gas              which              turns moist blue litmus red	NO – present (except those 3 of Na and K)
	e). Pungent smelling gas which turns red litmus blue.	NH + present 4
	f).Sublimation	Possibly NH + 4

 

Test for oxidizing and reducing agents

The usual method of testing for an oxidizing agent is to mix it with a substance which is easily oxidized (i.e. a reducing agent) and which gives a visible change when the reaction takes place. Similarly, a suspected reducing agent is added to an oxidizing agent which undergoes a visible change when reduced.

 

Test	Observation	Inference
1. Oxidising agents a). Test with moist starch- potassium iodide paper	Papers turns blue-black	I–ions are oxidized to I2: which then react with starch
b). Warm with Conc. HCl	Cl2(smell,   bleaches   moist litmus paper	Cl– Oxidised to Cl2
2. Reducing agents a).Add acidified KMnO4 solution	Purple solution is decolorized	Purple     MnO –(aq)                          reduced     to 4 colourless Mn2+(aq) ions
b). add acidified K2Cr2 O7(aq)	Orange solution turns green	Cr2 O 2- ions are reduced to green 7 Cr3+(aq) ions
c). Add a solution of an Iron(III)salt	Yellow solution turns pale Green	Fe3+(aq) ions reduced to Fe2+ions

 

Test	Observation	Inference
Add acidified KMnO4 solution to a solution in a test-tube	The purple KMnO4 turns colourless or decolourised	SO 2- ions present OR unsaturated 3 organic compound OR a reducing agent

 

Add acidified K2Cr2O7 solution to a solution in a test tube	It turns green or colour changes from orange to green	2- SO3   ions present OR unsaturated organic compound OR a reducing agent
Add bromine water to a solution in a test tube	It is decolourised or turns colourless	SO 2- ions present OR unsaturated 3 Organic compound OR a reducing agent
Add chlorine water to a solution in a test tube.	Brown solution/yellow solution	Br– of I– present
Add bromine water to a solution in a test tube	Brown                      solution/black precipitate	I– present

 

Candidates are advised that MARKS are only earned if observation is correct and the scientific language used to describe that observation. It should be known that if the observation is wrong or correct scientific language is not used, then all the marks will be lost.

 

 

 

 

 

OCTOBER – NOVEMBER 1989

1.                You are provided with;

• Aqueoushydrochloric acid, solution W9 in a burette.
• Solution sodium W11 containing 3g of a dibasic acid H2CO4.2H2O per litre
• Aqueous sodium hydroxide, solution W12.
• Phenolphthalein indicator
• A pair of scissors or a sharp blade

 

You are required to;

 

• Standardize the sodium hydroxide solution W11
• Use the standardized solution W11 to determine the concentration of W9

 

React the hydrochloric acid solution W9 with metal M and determine the                                                                                            mass per unit length of metal M.

 

Procedure

 

I         Fill a burette with solution W11, pipette 25.0cm³ of solution W12   into a conical flask. Titrate using phenolphthalein indicator. Record your results in Table A below;

 

Table A.

 

	1st	2nd	3rd
Final Burette Reading
Initial Burette Reading
Titre (cm3)

(5 marks)

 

1. Average volume of solution W11 used (1 mark)
2. Calculate the concentration of the dibasic solution W11 in mol^-1

(C=12, H=1, O=16)                                                                (1 mark)

• Calculate the concentration of the sodium hydroxide solution W12 in moll^-1

(2

marks)

 

10. Using a 100cm³ measuring cylinder measure 90cm³ of distilled water and place it into a 250cm³ beaker then add 10cm³ of solution W9 (W9 is supplied in a burette). Mix the solution well and label it W10.

 

Fill a burette with solution W10, pipette 25.0cm³ of solution W12 into a conical flask. Titrate using phenolphthalein indicator. Record your results in Table B below.

Table B.

	1st	2nd	3rd
Final Burette Reading
Initial Burette Reading
Titre (cm3)

(5 marks)

• Average volume of solution W10 (1 mark)
• Calculate the concentration of the diluted hydrochloric acid solution W10 in mol l-1. (2 marks)
• Determine the concentration of the original hydrochloric acid solution W9 in mol l^-1 (1 mark)

• Cut three pieces each of length 2cm from the metal M From the burette containing W9 measure 10cm³ of W9 into a boiling tube. Wrap the boiling tube with tissue paper. Measure the temperature of this solution and record it in Table C below. Place one of the 2cm pieces of metal M into the hydrochloric solution W9 in the boiling tube and measure the temperature. Record the highest temperature in table C below. Repeat this procedure using the other two, 2cm, pieces of M.

 

Table C.

	1st	2nd	3rd
Piece of metal M
Highest temperature
Initial temperature

 

Change in temperature, ∆T

(5 marks)

 

• Average change in temperature ∆T……………….⁰C (1 mark)
• Calculate the heat of the reaction between metal M and hydrochloric acid using the expression below; heat of reaction = 42 x ∆T Joules (1 mark)
• Given that the heat of the reaction is 440Kj per mole of M. Calculate the number of moles of M used in this (2 marks)
• Calculate the mass per unit length of metal M (M=24). (2 marks)

 

2. (10 Marks). You are provided with a solid Carry out the tests in Table D below on Y. Record your observations and deductions in the table. Identify any gas evolved.

 

		Observation	Deduction
a).	Place half a spatula end ful in a dry test-tube and heat gently first and then strongly	(1 mark)	(1 mark)
b).	To about half a spatula endful in a test tube add about 1cm3 of dilute hydrochloric acid	(1 mark)	(1 mark)
c).	Place a half a spatula end- ful in a test tube and about 6cm3 of distilled water and shake well. Divide the solution into two portions.
i).	To the first portion add dilute sodium hydroxide dropwise until in excess. Warm the resulting mixture gently then strongly.	(2 marks)	(2 marks)
ii).	To the second portion add aqueous ammonia dropwise until in excess.

 

(1 mark)

(1 mark)

 

OCTOBER /NOVEMBER 1990

 

1. (24 marks) You are provided with;
   • A monobasic acid solid D

• Sodium hydroxide, solution S1
• 01 M solution S2 of a dibasic acid H2A.

 

You are required to:

• Prepare a saturated solution of solid D
• Standardize the sodium hydroxide solution S1 using solution S2.
• Determine the solubility of Solid D in water at room

Procedure

• Place all the solid D provided into a dry conical flask. measure out 100cm³ of distilled water using a measuring cylinder and add it to the Solid D. Shake thoroughly and leave it to
• Fill a burette with solution S1. Pipette 25cm³ of solution S2 into a conical Titrate with Solution S1. Using a phenolphthalein indicator record the readings in the table below. Repeat to obtain three accurate readings.

 

Table A

	Trial	1st	2nd	3rd
Final Burette reading
Initial burette reading
Titre (cm3)

 

Average titre =………………………………………………………………….. cm³

(Show the value s being averaged)                                                           (1 mark)

 

Calculations:

• Write the equation for the reaction of the dibasic acid H2A with sodium ………………………………… (1 mark)
• Calculate the concentration of sodium hydroxide Solution S1 in moles per ……………………… ……………… (3 marks)

 

• Measure the temperature of the solution of solid D. Using a dry filter paper and a dry filter Filter the solution into a dry conical flask. Pipette 10cm³ of the filtrate into  a  conical  flask,  add  25cm³  of  distilled  water  using  a  measuring cylinder. Shake well and then titrate with the sodium hydroxide solution S1, using phenolphthalein indicator.

 

Record the readings in the table below. Repeat to obtain three accurate readings.

 

Temperature of solution of Solid D =……………………^o C                                                                                    (1 mark) Table B.

 

Trial 1st 2nd 3rd Final burette reading         Initial burette reading         Titre (Cm3)

(6 marks)

Average titre=……………………………………………………………

(Show the values being averaged)                                                          (1 mark)

 

Calculation;

• Calculate the number of moles of acid D in 10cm³ of the filtrate,

(1 mark)

• Calculate the number of moles of acid D in 100cm³ of solution of acid

(1 mark) iii).      Given  that  the  molecular  formula  of  acid  D  is  C7H6O2,  calculate  the solubility of the acid in grammes per 100cm³ of water (C=2, H=1, O=16).

(2

marks)

 

2.                (16marks)

You are provided with a solid Q. Carry out the tests below and record your observations and inferences in the spaces provided on the table below. Test for any gas (es) produced.

 

Table

	Test	Observations	Inferences
a).	Place a spatula endful of Solid Q in a boiling tube and add about 20cm3 of distilled water. Shake well. Use about 2cm3 portions of the solution for the tests below	(1 mark)	(1 mark)
i).	Test the pH with a pH paper	(1 mark)	(1 mark)
ii)	Add a spatula endful of sodium hydrogen carbonate	(1 mark)	(1 mark)
iii).	Add   two   drops   of         potassium manganate (VII)solution	(1 mark)	(1 mark)
iv).	Add two drops of bromine water and warm the solution then shake it well	(1 mark)	(1 mark)
b).	Place a little of solid Q in a crucible   (a   crucible   lid   or               a

 

	metallic spatula) and ignite it.	(1 mark)	(1 mark)
c).	Place about 4cm3 of ethanol in a test tube, add two drops of concentrated sulphuric acid then add a spatula endful of Solid Q. Warm the mixture carefully. Shake well and pour the mixture into about 20cm3 of cold water in a boiling tube. Note any smell	(1 mark)	(1 mark)

 

OCTOBER / NOVEMBER 1992

1. (15 Marks)

You are provided with:

• SolutionC2, Potassium iodate solution
• SolutionC3, acidified sodium hydrogen sulphite solution
• SolutionC4, starch indicator
• A stop watch/stop clock

 

You are required to find out the effect of the concentration of potassium iodate, C2, on the rate of reaction with acidified sodium hydrogen sulphite, C3.

 

NB: The end-point for the reaction of potassium iodate with acidified sodium hydrogen sulphite is detected by the formation of a blue- coloured complex using starch indicator.

 

Procedure

• Place solution C2 in a burette and measure out the volumes of C2 shown in

table 1 into six dry test-tubes. Using a 10cm³ measuring cylinder, add distilled water to the test-tubes as shown in table 1.

 

Test-tube	Volume of C2 and water
i).	10cm3 of C2 +0 cm3 distilled water
ii).	8cm3 of C2 + 2 cm3 distilled water
iii).	6cm3 of C2 + 4cm3 distilled water
iv).	4cm3 of C2 + 6 cm3 distilled water
v).	3cm3 of C2 + 7 cm3 distilled water
vi).	2cm3 of C2 + 8 cm3 distilled water

 

• Using a clean 10cm³ measuring cylinder, place 10cm³ of solution C3 intoa 100cm³ beaker, add 3 drops of solution C4 and shake To this mixture add quickly the contents of test-tube (i) and start the stop watch/stop clock immediately. Shake the mixture and note the time taken (in seconds) for the blue colour to appear.

 

Record the time in Table II

Repeat this procedure using the other solutions prepared in (a) above and complete Table II

 

 

 

 

 

TABLE II.

Volume   of               C3 (cm3)	Volume of C4 (drops)	Volume of C (cm3)	Volume of distilled water (cm3)	Time taken for blue colour to appear (seconds)
10	3	10	0
10	3	8	2
10	3	6	4
10	3	4	6
10	3	3	7
10	3	2	8

 

(6 Marks) c).          On the grid below plot a graph of volume (vertical axes) of solution C2 used versus time.          (5 Marks)

 

• From your graph determine the time taken for the blue colour to appear using a mixture of 7cm³ of C2 and 3cm³ of distilled (2 marks)

 

• How does the concentration of potassium iodate, C2, affect its rate of reaction with acidified sodium hydrogen sulphite, C3?Explain your answer.  (2 marks)

 

2. (15 marks)

 

You are provided with:

• Solution C5, 0.11M hydrochloric acid
• SolutionC6, containing 19.2g/l of basic compound Na2B4O7. nH2O

You are required to determine the value of n in compound C6 Na2B4O7. nH2O.

 

Procedure

• Placesolution C5 in the  Pipette 25.0cm³ (or 20.0cm³) of C6 into a 250cm³ conical flask and titrate using methyl orange indicator. Record your results in

Table III below and repeat the titration carefully to achieve consistent results

Volume of pipette………………………….. cm³

Burette readings

Table III

 

Titration number	I	II	III
Final reading (cm3)	28.5
Initial reading (cm3)	00.00
Volume of C4 use (cm3)	28.5

(5 marks) Average volume of C5 used = ……………………………..cm³                                                                              (1 mark)

b).               Calculations;

Given that the ionic equation for the reaction is

 

B O 2-

+ 2H+(aq) + 5H2O(l)                                                4H3BO3(aq)

 

4  7   (aq)

(1 mole of the base reacts with two moles of the acid)

 

i).       Calculate the concentration of C6 in moles per litre.          (4 marks) ii).          Calculate the relative molecular mass of the basic compound C6.

(2

marks)

iii).     Calculate the value of n in the formula Na2B4O7nH2O

(B=10.8, H=1.0, Na=23.0, and O = 16.0).                        (3 marks)

 

3.                (10 marks).

You are provided with solid C7. Carry out the following tests and record your Observations and inferences in the spaces provided in table IV.

 

Table IV

 

	Test	Observations	Inferences
a).	Place a little of solid C7 in a dry test-tube and heat gently.	(1 mark)	(1 mark)
b).	Place the remainder of the solid C7 in a boiling tube. Add about 10cm3 of distilled water and shake well to dissolve the solid. Divide the solution into four positions for tests (i) to (iv) below	( ½ mark)	(1 mark)
i).	To the first portion add a few drops of dilute sulphuric acid.	( ½ mark)	(1 mark)
ii).	To the second portion add dropwise aqueous sodium hydroxide until in excess	( ½ mark)	(1 mark)
iii).	To the third portion add one to two drops of aqueous lead nitrate	( ½ mark)	(1 mark)
iv).	To the fourth portion add a few drops of barium chloride solution	( ½ mark)	(1            ½ marks)

 

 

 

 

 

 

 

OCTOBER /NOVEMBER 1993

1.                (26 MARKS)

 

You are provided with:

• Sodium hydroxide, solution A
• 1.0 g of an ammonium salt, solid B
• 0.01M monobasic acid, solution C

 

You are required to:

• Dilute solution A with distilled water,
• Standardize the diluted solution A with solution C
• Determine the relative formula mass of the ammonium salt B

 

Procedure I

Pipette 25cm^{3 of} solution A into a 250cm³ conical flask, measure 175cm³ of Distilled water using 100cm³ measuring cylinder and add it to solution A in the beaker. Shake well. Label this as solution D. Pipette 25cm³ of solution D into a 250cm³ conical flask and then titrate with solution C using 1 or 2 drops of Phenolphthalein indicator. Record your results in table I below. Repeat the procedure to obtain accurate values.

 

Table I

Table I	1st	2nd	3rd
Final burette reading (cm3)
Initial burette reading (cm3)
Volume of solution C used (cm3)

 

Calculations:

a).     Determine the average volume of solution C used.                                  (1 mark)

1. b) Calculate the concentration in moles per litre, of sodium hydroxide in solution

(1 mark)

c).      Calculate the concentration, in moles per litre of sodium hydroxide in solution A.

(1 mark)

 

In the process described below, sodium hydroxide reacts with the ammonium Salt B and on boiling the mixture, ammonia gas is expelled. The excess sodium hydroxide is then determined by titrating the monobasic acid, solution C.

 

 

 

 

 

Procedure II

Place all the 1.0g of ammonium salt, solid B into 250cm³ conical flask. Pipette 25cm³ of the sodium hydroxide solution A into the conical flask containing solid B. Shake well until all the solid dissolve. Heat the mixture and let it boil for about 10 minutes. Add 50 cm³ of distilled water to the boiled mixture and shake well. Transfer the solution into a 100cm³ measuring cylinder then add distilled water up to the 100cm³ mark. Pour this solution back into the conical flask and label it as solution E. Pipette 25cm³ of solution E into a 250 cm³ conical flask and titrate with solution C using 1 or 2 drops phenolphthalein indicator. Record the results in the table II below. Repeat the procedure to obtain accurate value and complete Table II

 

Table I	1st	2nd	3rd
Final burette reading (cm3)
Initial burette reading (cm3)
Volume of solution C used (cm3)

 

Calculations:

• Determine the average volume of C (1 mark) b).          Calculate:
  1. The number of moles of the monobasic acid, Solution C, used

(2

marks)

• The number of moles of hydroxide in 25cm³ of solution E. (1 mark)
• The number of moles of sodium hydroxide in 100cm³ of solution E.

(1

mark)

• Using concentration of sodium hydroxide solution, obtained in (e) above calculate the moles of sodium hydroxide in 25cm³ of solution A (this gives the number of moles of sodium hydroxide added to the ammonium salt B)

(2

marks)

• Using the values obtained in (e) (iii) and (f) above determine the number

of   moles    sodium    hydroxide   that   reacted   with   the       ammonium          salt.

(2 marks) e).     Given that one mole of sodium hydroxide reacts with one mole of the

ammonium Salt B, what is the number of moles of salted in 1.0g of Solid B.

(2 marks) f).          Calculate the relative formula of mass of the ammonium salt.          (2 marks)

 

 

 

 

 

2.                (14 marks)

You are provided with solid F. You are required to carry out the tests below and write your observation and inferences in the spaces provided. Identify the gas or gases produced.

 

Table

	Test	Observations	Inferences
	Place all the solid F provided into a boiling tube and add distilled water with shaking until the boiling tube is half full. Use about 3cm3 portions of the solution for tests (a) to (d) below.	(1 mark)	(1 mark)
a)	To the 1st portion add sodium hydroxide solution drop wise until in excess	(1 mark)	(1 mark)
b)	To the 2nd portion add about six drops of barium chloride solution	(1 mark)	(1 mark)
c)	To the 3rd portion add three drops of iodine solution	(1 mark)	(1 mark)
d)	Dip one end of the filter paper strip provided into potassium dichromate solution and remove it. To the 4th portion add about 1cm3 of dilute hydrochloric acid, shake well, and observe for about 2 minutes. Place the dipped end of the filter paper at the mouth of the test tube and warm the contents of the test tube gently.	(3 marks)	(3 marks)

 

OCTOBER / NOVEMBER 1994

1.                You are provided with:

• 2M sodium hydroxide, solution D
• 1M solution of a carboxylic acid C3H5O (COOH) n solution E

You are required to determine the value of n in the formula C3H5O (COOH)n of the carboxylic acid E

 

Procedure

• Place solution D in the Pipette 25.0cm³ (or 20.0cm³) of solution E into a conical flask and titrate with solution D using phenolphthalein indicator. Record your

 

results in table l below and repeat the titration to achieve consistent                                                                                                              results.

 

Results

Volume of pipette………………… cm³

Table I

Burette readings

Titration number	I	II	III
Final reading (cm3)
Initial reading (cm3)
Volume of D used (cm3)

4 marks

• Average volume of D…………………

(Show how you arrive at your answer)

• Calculate the number of moles of sodium hydroxide 2 marks
• Calculate the number of moles of E in the 0cm³ (or 20.0cm³) used

 

2 marks

• i). Calculate the number of moles of sodium hydroxide required to react with one mole of C3H5O(COOH)n                                                                                                     3 marks

ii).      What is the value of n                                                    1 mark

 

2.                You are provided with;

1.0M Sodium hydroxide solution F 0.63M solution of an acid solution G

 

You are required to determine the molar heat of neutralization of sodium hydroxide with acid G.

 

Procedure

a).      Place six test-tubes on a test-tube rack. Using a 10cm³ measuring cylinder, measure 5cm³ portions of solution G and place them into each of the six test- tubes.

 

Measure 25.0cm³ of solution F using a measuring cylinder and place it into a 100cm³ beaker. Measure the temperature of this solution F to the nearest 0.5⁰C and record it in table II.

 

Pour the first portion of the 5cm³ of solution G from the test-tube into the beaker containing 25cm³ of solution F, stir the mixture carefully and record the highest temperature of the mixture in table II.

 

Pour the second portion of solution G immediately into the mixture in the beaker, stir carefully and record the highest temperature of this mixture in Table II. Continue this procedure using the remaining portions of solution G to Complete table II.

Table II

 

24

Ch

emToisttaryl Pvoralcutmicael SotfuGdyaPdadcked (cm3)

19089

– 52016

10

15

20

25

30

 

Volume of F (cm3)	25	25	25	25	25	25	25
Temperature (0C)

 

 

 

 

 

 

 

 

 

 

 

 

 

mark

4 marks

• On the grid provided below, plot a graph of temperature (vertical axes) versus volume of solution G added 4 marks
• From the graph determine:
• The volume of the solution G required to neutralize 25cm³ sodium hydroxide solution F 1 mark
• The highest temperature change, ∆T, 1 mark
• Calculate the heat change for the reaction. (Heat change = mass x temperature change x 4.2Jg^{-1 0}C^-1. Assume density of each solution to be 1gm cm^-3) 2 marks
• Calculate the number of moles of sodium hydroxide, solution F,

1

 

• Calculate the molar heat of neutralization of the sodium hydroxide solution 1 mark

 

 

3. a). You are provided with the following solids:

Sodium chloride, potassium chloride, calcium chloride and solid H Note: Solid H will also be required for Question 3 (b)

 

You are required to carry out flame tests on the above solids to identify the flame colour of the cations present in each of them.

 

Procedure:

Clean a metallic spatula and rinse it with distilled water. Dry the spatula on a Bunsen flame for about 1 minute. Allow it to cool. Place a little of sodium chloride solid of the flame as the solid burns and record it in Table III below. Clean the spatula thoroughly using steel wool, and repeat the procedure using each of the other solids and complete the Table III.

 

i).                Table III

Solid	Colour of flame
Sodium chloride
Potassium chloride
Calcium chloride
Solid H

 

4 marks

 

• What cation is present in solid H? 1 mark

b).      You are provided with solid H. Carry out the tests in table IV below and record your observations and inferences in the spaces provided. Identify

 

any gas (es) produced.

 

Table IV

 

	Test	Observation	Inferences
i).	Place a little of solid H in a dry test- tube and heat strongly	(1 mark)	(1 mark)
ii).	Place the remainder of the solid H in a boiling tube. Add about 10cm3 of distilled water and shake well. Divide the mixture into three portions for tests (I to III) below
	I.    To the first portion add aqueous sodium hydroxide until in excess	(1 mark)	(1 mark)
	II.   To the second portion add aqueous ammonia until in excess	(1 mark)	(1 mark)
	III. To the third portion add about 1cm3 aqueous sodium chloride	(1 mark)	(1 mark)

 

 

October /November 1995

1. (22 Marks).

 

You are provided with

• 0g of potassium hydrogen carbonate solid J
• 1.0g of magnesium carbonate, solid K
• 0M Hydrochloric acid

 

You are required to determine the enthalpy change for the reaction between a).   Potassium hydrogen carbonate and hydrochloric acid

• Magnesium carbonate and hydrochloric acid
• Aqueous magnesium chloride and aqueous potassium hydrogen

 

 

 

 

 

Procedure

1. By means of a burette place 15.0cm³ of the 2.0M hydrochloric acid in a 100cm³ Stir gently and take the temperature of the acid at every half-minute. Record your readings in table 1. at exactly 2½ minutes add all solid J to the acid, stir gently and continue taking the temperature every half-minute 5 record your

 

Time (min) 0 ½ 1 1 ½ 2 2 ½ 3 3 ½ 4 4 ½ 5 Temperature (0C)

readings in table I. Table

 

 

On the grid provided plot a graph of temperature against time and determine from it the fall in temperature ∆T1. Show the change ∆T1 on the graph

(3

marks)

Fall in temperature ∆T1                                                                                                         (1 mark)

Calculations; use the following information where necessary

(H=1, C=12, O=16, Mg=24, k=39) Assume density of the solutions to be 1.0gcm³

 

a).               Calculate;

• Thenumber of moles, n1, of potassium hydrogen carbonate (KHCO3) used during procedure I       (1 mark)
• The enthalpy, change ∆H2 for the reaction between potassium hydrogen carbonate and hydrochloric acid. Show the sign. Use the following expression (2 marks)

 

 

• Calculate;

∆H1  = Mass of solution x 4.2 x ∆T1

n1 x 1000

-1

Kjmol

 

• Thenumber of moles N2, of magnesium carbonate (MgCO3) used in procedure II                                                                       (1 mark)
• The enthalpy  change  ∆H2,  for  the  reaction  between  magnesium carbonate and hydrochloric acid. Show the sign. Use the following

 

Mass of solution x 4.2 x ∆T2

∆H2 =                                                       Kjmol^-1

n2 x 1000                                    (2 marks)

 

• The equations for the reactions taking place in procedures I and II are; KHCO3(s) + HCl(aq) KCI(aq) + CO2(q) + H2O(l)

and MgCO4(s) + 2HCl(aq)                          MgCl2 (aq) + CO2(q) + H2O(l) Given that the enthalpy change, ∆H3 for the process.

KHCO3 (s)                             KHCO3(aq) = 121 kjmol^-1 determine the Enthalpy

change          ∆H4 for the reaction represented by the equation

 

MgCl2(aq) + 2KHCO3(aq)                             MgCO3(s) + 2KCl(aq) + H2O(l) + CO2(g)

Use the following expression

∆H4=2∆H1 – ∆H2- 2∆H3                                                                                       (2 marks)

 

2.                (9 Marks)

You are provided with solid L. You are required to carry out the tests below and write your observations and inferences in the spaces provided.

 

Identify any gases evolved

a).      Describe the appearance of solid L          (1 mark) b).          Place a little of solid L, in a dry clean test tube and heat strongly

Observations                                                   Inferences

 

(1 mark)

• Place a little L in a dry clean test tube then add about 2cm³ of distilled Shake well then warm the mixture

Observations                                                   Inferences

 

(1 mark)

• Place a little solid L in a dry clean test tube then add about 2cm³ of dilute hydrochloric acid

Observations                                                  inferences

 

(1

mark)

• place about 2cm³ of lead nitrate solution in a clean test tube, add a little of solid L Shake well and allow to settle for about 5 minutes

 

 

 

 

 

 

 

 

 

3. (9 marks)

You are provided with solid N. You are required to carry out the tests below and record your observations and inferences in the spaces provided. Identify any gases evolved using a glowing splint and litmus paper

a).     Describe the appearance of Solid N.                                                                                    (1 mark) b). Place a little of Solid N on a clean metallic spatula and burn it in a

Bunsen flame                                                                      (1 mark)

 

 

 

 

mark)

• Place a little of Solid N in a dry clean test tube and heat strongly Observations inferences

(1

 

 

d). Place the remaining solid N in a boiling tube and add about 20cm³ of distilled water. Shake well until all the solid dissolves. Use about 2cm³ portions of this solution for the tests below.

i). Test the 1^st portion with red and blue litmus papers Observations                                  Inferences

 

 

ii).

To the 2^nd portion add a shake well after every drop Observations

(1 mark)

 

few drops of dilute sodium hydroxide

 

Inferences

 

(1 mark)

 

• To the 3^rd portion add a few drops of dilute lead Shake well after every drop

Observations                                                                      Inferences

(1 mark)

 

• To the 4^th portion add about 1cm³ of dilute sodium hydroxide followed by a small piece of aluminium Warm the mixture gently and carefully

Observations                                                                      Inferences

(1 mark)

 

 

 

 

 

 

 

OCTOBER /NOVEMBER 1996

1.                You are provided with:

• Acidifiedaqueous potassium manganate (VII) KMnO4, solution A.
• Solution B, containing 5g of ammonium Iron (II) Sulphate (NH4)2Fe (SO4)2 6H2O,per litre.
• SolutionC, Containing 5.0g of a dibasic acid, H2X 2H2O, per litre

 

You are required to:

 

• Standardize  the   potassium   manganate   (VII),   solution   A,   using   the ammonium iron (II) sulphate, solution B.
• Use the standardized potassium manganate (VII), solution A, to determine theconcentration of the dibasic acid, H2X 2H2O, solution C and then the formula mass of

 

Procedure I:

 

Fill the burette with solution A.

Pipette 25.0cm³ of solution B into a conical flask. Titrate solution B with solution A until a permanent pink colour just appears. Record your results in table I below. Repeat this procedure to complete table I.

 

a).      Table I

	I	II	III
Final burette reading (cm3)
Initial burette reading (cm3)
Volume of solution A (cm3)

4 marks b).          Record average volume of solution A used, V1             cm³

(Show how you arrive at your answer)                                  1 mark

 

• Calculate the concentration of the ammonium iron (II) sulphate, solution B, in moles per (RFM of (NH4)2 Fe (SO4)2 .6H2O = 392 1 mark
• Calculate the number of moles of iron (II) ions in the 0cm³ of solution B

1 mark

• Using the ionic equation for the reaction between manganate (VII) and iron

(II) ions, given below, calculate the concentration of manganate (VII) ions in solution A in moles per litre.

 

MnO4(aq) + 5Fe2+(aq) + 8H+(aq)                              Mn2+(aq) + 5Fe3+(aq) + 4H2O(l)

 

 

Procedure II

Pipette 25.0cm³ of solution C into a conical flask. Heat this solution to about 70⁰C and titrate the hot solution C with solution A until a permanent pink colour just appears. Shake the thoroughly during the titration. Record your results in table II. Repeat this procedure to complete Table II.

 

f).               Table II.

 

	I	II	III
Final burette reading (cm3)
Initial burette reading (cm3)
Volume of solution A (cm3)

 

 

 

 

 

 

 

 

 

 

 

marks

4 marks g).          Record average volume of solution A used V2=………………… cm³

Show how you arrive at your answer.

• Calculate the number of moles of the manganate (VII) ions in volume V2

1 mark

• Given that 2 moles of the manganate (VII) ions react with 5 moles of the dibasicacid, H2X. 2H2O, calculate the number of moles of the dibasic acid,

H2X 2H2O, in the 25cm³ of solution C.                                      2 marks

• Calculatethe concentration of the dibasic acid, H2X. 2H2O in moles per litre                                                                                    1 mark
• Calculate the formula mass of x in the dibasic acid H2 2H2O

(H = 1.0 O=16.0)                                                                              3

 

 

2. (8 marks) You are provided with solid Carry out the tests below.

Record observations and inferences in the table. Identify any gas (es) evolved.

 

Divide solid D into portions

 

• i). To one portion of D in a dry test-tube add about 1cm³ of 6M hydrochloric acid and warm gently for about one minute

Observation s                                                                      Inferences

 

2 marks                                                           1 mark

 

ii).      Add distilled water to the mixture in (a) (i) above until the test-tube is about half-full. Shake well and filter into a boiling tube. To about 1cm³ of the filtrate in a test-tube add about 1cm³of 2M sodium          hydroxide drop wise

Observations                                                             2 marks

• Place the remaining portion of D in a dry test-tube and about 1cm³ of 20 volume hydrogen peroxide

Observations                                                                                Inferences

 

 

 

 

3. (11marks) You are provided with solid Carry out the tests below and record the observations and inferences in the spaces provided. Identify any gas (es) produced.

 

• Place a little of E on a clean metallic spatula and ignite with a bunsen

Observations                                                   inferences

31    Chemistry Practical Study Pack                 1989 – 2016

 

• mark 1 mark

 

• Add a little of solid E to about 2cm³ of distilled water in a test-tube and shake Test the mixture with litmus paper.

Observations                                                   inferences

 

• marks 1 mark

 

• Add a little of solid E to about 2cm³ of 2M aqueous sodium hydroxide in a test-tube and shake well

 

• Place the remaining portion of E in a boiling tube, add about 10cm³ of distilled water and heat the Divide the mixture, while still hot, into two portions:
  • Add a little of solid sodium hydrogen carbonate to the first portion Observations inferences

 

1 mark                                                  1 mark

• Add about 2-3 drops of concentrated sulphuric acid to the second Shake well, and then add about 1cm³ of ethanol. Warm the mixture.

OCTOBER /NOVEMBER 1997

1. You are provided with;
   • Sulphuric acid, solution F
   • 5M sodium hydroxide, solution G
   • Magnesium turnings, solid H

 

You are required to determine the concentration of sulphuric acid in moles per litre

 

Procedure I

Measure 50cm³ of solution F using a measuring cylinder and place it in a 100 cm³ beaker. Stir the solution gently with a thermometer and take its temperature after every half-minute. Record your results in Table I.

 

After one and half minutes, add all of solid H at once. Stir the mixture gently with the thermometer and record the temperature of the mixture after every half-minute in table I

 

Time (min) 0 ½ 1 1 ½ 2 2 ½ 3 3 ½ 4 4 ½ 5 5 ½ 6 Temperature (0C)

up to the sixth minute. Keep the solution for use in procedure II a).          Table I

 

 

(5 marks) b).    Using the results in table I, determine the highest change in temperature,

∆T for the reaction

∆T……………….                                                            (1 mark)

c).      Calculate the heat change for the reaction using the expression Heat change = Mass of solution x 4.2 x ∆T Joules

(Assume density of solution = 1.0g/cm³)          (3 marks) d).          Given that the molar heat of reaction of sulphuric acid with solid H is

323KJ mol^-1, calculate the number of moles of sulphuric acid that were used during the reaction                                                                                    (2 marks)

 

Procedure II

Place all the solution obtained in procedure I in a clean 100m³ measuring cylinder. Add distilled water to make 100cm³ of solution. Transfer all the solution. Transfer all the solution into a beaker and shake well. The resulting solution is ‘solution K’.

 

Fill a burette with solution G. Pipette 25.0cm³ of solution K into a conical flask. Add 2- 3 drops of phenolphthalein indicator and titrate with solution G. Record your results in table II. Repeat the titration two more times.

Table II.

	I	II	III
Final burette reading (cm3)
Initial burette reading (cm3)
Volume of solution G used (cm3)

 

 

 

 

 

 

 

mark)

 

mark)

(6 marks) e).          Determine the average volume of solution G used                         (1 mark)

• Calculate the number of moles of sodium hydroxide, solution G that were (2 marks)
• Determine;
  • The number of moles of sulphuric acid in 0cm³ of solution K.

(1

 

• The number of moles of sulphuric acid in 100cm³ of solution K.

(1

 

• Using the results from (d) and g (ii) above, calculate the total number of moles of sulphuric acid in 50cm³ of solution

(1 mark)

 

2. You are provided with solid Carry out the tests below. Write your observations and inferences in the spaces provided.

 

a).	Place all of solid L in a dry test-tube and heat it until it just turns reddish- yellow at the bottom. Test the gas with a glowing wooden splint. Keep the residue for tests in (b) Observations                                                                                    inferences   (2 marks)
b). i).	Allow the residue from (a) above to cool for about three minutes. Add 5-6 drops of concentrated nitric acid, then add distilled water until the test-tube is three quarters full. Filter the mixture into a boiling tube then add more distilled water to the filtrate until the boiling tube is half-full. Shake well. Use the solution obtained for the tests below Observations (1 mark)
ii).	To about 2cm3 portion of the solution in a test–tube, add 2M of sodium hydroxide dropwise until in excess Observations                                                                inferences (3 marks)
iii).	To  another  2cm3  of  the  solution  in  a  test-tube,  add  aqueous  ammonia dropwise until in excess Observations                                                                                        Inference   (2 marks)
iv).	To a third 2cm3 of the solution, add a few drops of 2M sulphuric acid   Observations                                                                                  Inferences 1mark                                                                    1 mark

 

3. You are provided with an organic compound, solid M. Carry out the tests below. Write your observations and inferences in the spaces provided

 

Place all solid M in a boiling tube. Add distilled water until the boiling tube is half- full. Shake the mixture thoroughly until all the solid dissolves. Use the solution for the tests below.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OCTOBER /NOVEMBER 1998

1.                (20 marks) You are provided with:

• Solution M, hydrochloric acid
• Solution N, containing 8.8g per litre of sodium hydroxide
• 0.5g of an impure carbonate, solid P

 

You are required to determine the:

a). Concentration of solution M in moles per litre b).      Percentage purity of the carbonate, solid P.

 

Procedure I.

Fill the burette with sodium hydroxide, solution N. Pipette 25.0cm³ of hydrochloric acid, solution M into a conical flask. Add 2-3 drops of screened methyl orange indicator and titrate. (The colour of the indicator changes from pink to green) record your results in table I below. Repeat the titration two more times and complete the table.

 

Table	1	2	3
Final burette reading
Initial burette reading
Volume of solution N used (cm3)

(4 marks)

 

What is the average volume of solution N used?                                                                                                (1 mark) Determine;

• The concentration of solution N in moles per litre. (Na=23.0, O=16.0, H=1.0)

(1 mark)

• Concentration of solution M in moles per litre (1 mark)

 

Procedure II

Using a measuring cylinder, measure out 100cm³ of solution M into a 250cm³ beaker. Add all of solid P into the beaker containing solution M. Swirl the mixture and allow the reaction to proceed for about 4 minutes.

Label the solution with sodium hydroxide, solution N. Pipette 25.0cm³ of solution Q into a conical flask. Add 2-3 drops of screened methyl orange indicator and titrate. Record your results in table II below. Repeat the titration two more times and complete the table.

 

Table II	1	2	3
Final burette reading
Initial burette reading
Volume of solution N (cm3)

(4 marks)

What is the average volume of solution N Used? a).          Calculate the:

i).       Moles of hydrochloric acid in 25.0cm³ of solution Q          (2 marks) ii).          Moles of hydrochloric acid in 100cm³ of solution Q          (1 mark) iii).          Moles of hydrochloric acid in 100cm³ of the original hydrochloric

acid solution M.                                                                                (1mark)

• Moles of hydrochloric acid that were used up in the reaction with solid (1 mark)
• Moles of the carbonate that reacted with hydrochloric acid

(1 mark)

b).      Given that the relative formula mass of the carbonate is 72, calculate the; i).          Mass of the carbonate that reacted          (1 mark)

ii).       Percentage purity of the carbonate, solid P                      (1 mark)

 

2.             (12 marks)

You are provided with solid S. Carry out the tests below and record your observations and inferences in the spaces provided.

• Place about one third of solid S in a dry test-tube. Heat the solid gently and then Test any gases produced with red and blue litmus papers.

Observations                                                                                Inferences

 

 

 

• Dissolve the remaining portion of solid S in 8cm³ of distilled Divide the solution into four portions.
  • To the first portion, add aqueous sodium hydroxide dropwise until

 

 

in excess

Observations                                                                                Inferences

 

(1 mark)                                               (2 marks)

• To the second portion, add aqueous ammonia dropwise until in excess

Observations                                                                                Inferences

 

(1 mark)                                               (1 mark)

• To the third portion, add 10cm³ of barium chloride

Observations                                                             Inferences

 

(1 mark)                                               (1 mark)

 

• To the fourth portion, add 1 cm³ of lead (II) nitrate

Observations                                                             Inferences

(1 mark)                                              (1 mark)

3.             (8 marks)

You are provided with solid L. Carry out the tests below and record your observations and inferences in the spaces provided.

1. Place about half of solid L in a dry test-tube and heat it strongly. Test any gases produced with red and blue litmus papers and also with a burning

Observations                                                                                Inferences

 

(2 marks)                                                        (1 mark)

 

1. Place the rest of solid L in a boiling tube and add about 10cm³ of distilled Shake well to dissolve all the solid.
   • To about 1cm³ of the solution, add 3 drops of universal indicator solution and find its pH

• To the rest of the solution, add about 5cm³ of 2M dilute hydrochloric acid Filter the mixture and retain the residue for test(c) below.

Observations                                                                                 Inferences

(1 mark)

 

• Transfer the residue from b (ii) above into a boiling Add about 10cm³ of distilled water. Warm the mixture and add a little solid sodium carbonate

Observations                                                                                Inferences

37	Chemistry Practical Study Pack                                                                1989 – 201	6

 

(1 mark)                                               (1 mark)

 

 

 

 

 

 

 

 

 

 

 

OCTOBER / NOVEMBER 1999

1.                You are provided with:

• Solution E 099M hydrochloric acid
• Solution F containing 15.3g per litre of a basic compound,
• G2X10H2 O→14.3gNa2CO310H2O

You are required to determine the relative atomic mass of G. Procedure:

Place solution E in a burette.

Pipette 25cm³ of solution F into a 250cm³ conical flask. Add two drops of methyl orange indicator and titrate. Record your results in the table below. Repeat the procedure two more times and complete table I.

 

• i).

	I	II	III
Final burette reading
Initial burette reading
Volume of solution E used (cm3)

(3 marks)

Table I

ii).      What is the average volume of solution E?

 

• Given that one mole of F reacts with 2 moles of E. Calculate the:
  • Number of  moles  of  the basic compound,  G2X.10H2O  in the volume of solution F
  • Concentration of solution F in moles per
  • Relativeformula mass of the basic compound, G2X10H2O.
  • Relative atomic mass of (relative formula masses of X= 60 atomic masses of H=10, O=16.0)

 

2.                You are provided with:

• Magnesium ribbon labeled solid K
• 0M hydrochloric acid labeled solution L
• Stop clock /watch

 

You are required to determine the rate of reaction between magnesium and hydrochloric acid at different concentrations

 

 

 

Procedure.

1. Place the five test tube on the test tube rack and label them 1,2,3,4,and 5. Using a 10cm³ measuring  cylinder ,measure out   the volumes   of 2.0M hydrochloric acid  shown,  solution  L  as  shown    in    table  II  and  pour    them  into    the corresponding test tube. Wash the measuring cylinder and use it to measure the volumes of water as indicated in the table and pour into the corresponding test
2. Cut out five pieces each of exactly 1cm length of magnesium
3. Transfer all the solution in the test tube 1 into a clean 100cm³ Place one piece of magnesium into the beaker and start a stop clock/watch immediately. Swirl the beaker continuously ensuring that the magnesium is always inside the solution. Record in the table the time taken for the magnesium ribbon to disappear. Wash the beaker each time.

 

4. Repeat procedure III for each of the solutions in the test-tube 2, 3, 4 and 5 and complete the

a).

Test-tube Number	1	2	3	4	5
Volume of solution L (cm3)	10	9	8	7	6
Volume of water (cm3)	0	1	2	3	4
Time taken (sec)
Rate of reaction = 1/time

 

Table II

b). i). Plot a graph of rate of reaction ¹/time (y-axis) against volume of solution L                                                              (3 marks)

• Use the graph to determine the time that would be taken for a 1cm length of magnesium ribbon to disappear if the volume of the acid was 5cm³ (2 marks)
• In terms of rate of reaction, explain the shape of your graph.

(1 ½ marks)

3. You are provided with solid H. Carry out the tests below and write your observation an d inferences in the spaces

 

• Place about half of the solid H in a clean dry test tube. Heat the solid gently and then Test for any gas produced using both blue and red litmus papers

Observations                                                  Inferences

(4½ marks)

• Dissolve the remaining portion of Solid H in about 8cm³ of distilled water contained in a boiling tube. Divide the solution into three

 

 

i). To the first portion ,add aqueous sodium hydroxide drop wise until in excess.

Observations                                                   Inferences

(2½ marks) ii). To the second portion, add two drops of concentrated nitric acid

then add aqueous sodium hydroxide drop wise until in excess Observations                                                                 Inferences

 

(1½ marks) iii).  I.        To the third portion, add 2-3 drops of barium chloride solution

Observations                                                   Inferences

(1½ marks)

1. To the mixture obtained in (iii) I above, add about 2cm³ of 2M aqueous hydrochloric acid.

Observations                                                   Inferences

 

(2 marks)

 

 

OCTOBER / NOVEMBER 2000

1.                You are provided with:

• Solution L containing 6g per litre of anhydrous sodium carbonate
• Solution M: Hydrochloric acid
• Phenolphthalein indicator
• Methyl orange indicator

You are required to standardize the hydrochloric acid, solution M. Procedure

Fill the burette with solution M. Pipette 25cm³ of solution L into a conical flask. Add

three drops of phenolphthalein indicator and titrate with solution M. Record the readings

 

in table I below. Add 3 drops of methyl orange indicator to the contents of the conical flask and continue titrating with solution M. Record the readings in table II below. Repeat the procedure and complete tables I and II.

 

 

 

 

a).   i).   Table I (Using phenolphthalein indicator)

 

	1st	2nd
Final burette reading
Initial burette reading
Titre (cm3)

(3 marks)

 

Find average titre t1                                                                                                 (½ mark)

…………………………………………………………………..

 

Table II (Using methyl orange indicator)

 

	1st	2nd
Final burette reading
Initial burette reading
Titre (cm3)

(3 marks)

Find average titre t2                                                                                  (½ mark)

……………………………………………………………………..

 

• Total volume of solution M used = t1 + t2 = ………………………….

(1 mark)

 

• Calculate the:
  • Concentration of sodium carbonate in moles per litre (Relative formula mass of Na2CO3 = 106) (2marks)
  • Moles of sodium carbonate in 25cm³ of solution (1 mark)
  • Moles of hydrochloric acid in the total volume of solution M used.

(1

mark)

• Concentration of hydrochloric acid in moles per (2 marks)

 

2. You are provided with 0g of Potassium nitrate labeled solid G. You are required to determine the enthalpy of solution of solid G.

 

Procedure

Using a measuring cylinder, place 30cm³ of distilled water into a 100cm³ beaker. Stir the

 

water gently with a thermometer and take its temperature after every half minute. Record the readings in table III below. At exactly two minutes, add all solid G to the water at once. Stir well and take the temperature of the mixture after every half minute up to the fourth minute

 

Record your results in table III.

Table III a).

Time (min)	0	½	1	1 ½	2	2 ½	3	3 ½	4
Temperature (0C)

 

(3marks) b).      On the grid provided, plot a graph of time against temperature

• On the graph, show the change in temperature, ∆T (1 mark) Calculate:
  • The number of moles of solid G used in the experiment. (K=39.0, N=14.0, O=16.0) (1 mark)
  • Theenthalpy of solution, ∆Hsoln and show the sign of ∆Hsoln (Assume density of solution = 0g/cm³

Specific heat capacity of solution = 4.2jg^-1 k^-1)                     (3 marks)

 

3. You are provided with 10 cm³ of solution P in a conical Solution P contains two cations and one anion. Carry out the test below and record your observations and inferences in the spaces provided.

 

• Add 20cm³ of 2M aqueous sodium hydroxide to all solution P

Shake well. Filter the mixture into a conical flask. Retain both the filtrate and the residue.

Observations                                                                                Inferences

(2 marks)                                                                  (1 mark)

 

• i). To about 2cm³ of the filtrate, add 2M nitric acid dropwise until in excess (i.e. about 1cm³ of the acid). Retain the

 

Observations                                                                      Inferences

(2 marks)                                                        (1 mark)

 

Divide the mixture in (b) (i) above into two portions

• To the first portion, add aqueous sodium hydroxide dropwise until in excess

Observations                                                                      Inferences

(2 marks)                                                        (2 marks)

 

• To the second portion, add aqueous ammonia dropwise until the excess (i.e. about 5cm³ of aqueous ammonia)

 

Observations                                                                      Inferences

(1 mark)                                                         (1 mark)

 

• To 2cm³ of the filtrate, add 3 drops of 2M hydrochloric

Observations                                                                                Inferences

(1 mark)                                                                   (1 mark)

 

• To 2cm³ of the filtrate, add 3 drops of acidified chloride

Observations                                                                                Inferences

(1 mark)                                                                   (1 mark)

 

• To the residue, add about 5cm³ of dilute nitric acid and allow it to filter into a test-tube. To 2cm³ of this filtrate, add aqueous ammonia dropwise

until in the excess then filter into a clean test-tube.

Observations                                                   Inferences

(1 mark)                                                         (1 mark)

 

OCTOBER / NOVEMBER 2001

1.                You are provided with:

• Sodium hydroxide labeled solution A
• 128M hydrochloric acid labeled solution B.
• Carboxylic acid labeled solution C.

 

Solution D prepared by diluting 25cm³ of solution A with distilled water to 150cm³ of solution. You are required to:

• Standardise solution D with solution B b). Determine the:
  • Reaction ratio between sodium hydroxide, solution A and the carboxylic acid solution C
  • Concentration of solution C in moles per

 

Procedure I

Fill a burette with solution B. Pipette 25cm³ of solution D into a 250cm³ conical flask. Add 2 drops of phenolphthalein indicator and titrate with solution B. Record your results in table 1. Repeat the titration two more times and complete the table.

 

	I	II	III
Final burette reading
Initial burette reading
Volume of solution B used (cm3)

 

(4 marks)

 

• Determine the average volume of the solution B used (1 mark) b).         Calculate the concentration in moles per litre of sodium hydroxide in:
  • solution D (2 marks)
  • solution A (1 mark)

 

Procedure II

Using a clean burette, place 16cm³ of solution C into a boiling tube. Take the initial temperature of the solution in the boiling tube and record it in table II. Using a clean measuring cylinder, measure 4cm³ of solution A into 100cm³ beaker and add it to a solution C in the boiling tube. Stir the mixture immediately with a thermometer and record in table II the maximum (final) temperature reached. Repeat the experiment with the other sets of volumes of C and A in the table and complete it. (Rinse the thermometer and the boiling tube with distilled water after each experiment)

 

Table II

Volume of solution C(cm3)	16	12	8	6	4	2
Volume of solution A (cm3)	4	8	12	14	16	18
Final temperature (OC)
Initial temperature (0C)
Change in temperature , (∆T)

(6 marks)

 

• On the grid provided ,plot a graph of ∆T (vertical axis)against the volume of sodium hydroxide ,solution A           (3 marks)
• From the  graph,  determine  the  volume  of  sodium  hydroxide  solution  a required to neutralize the carboxylic                                                                           (1 mark)
• Calculate the volume of carboxylic acid, solution C used for neutralization.

(1 mark)

• Calculate the:
  • Ratio between the volumes of solutions A and (1 mark)
  • Concentration in  moles  per  litre  of  carboxylic  acid,  solution  C. (assume that the volume ratio is the same as the mole ratio)

(2 marks)

 

 

 

 

 

 

 

2. You are provided with solid E. carry out the tests below and record your observation and inference in the spaces

Divide solid E into two halves.

 

 

• You are provided with Solid F. carry out the tests below and record your observation and inferences in the spaces Place all the Solid F into a boiling tube. Add 10cm³ of distilled water and shake well. Use 2cm³ portion of the mixture for the following reactions.

 

a). Test the first portion with both blue and red litmus papers Observations                                         Inferences (2 marks)

b). To the second portion, add three drops of bromine water Observations                                        Inferences (2 marks)

c). To the third portion, add 2 drops of acidified potassium permanganate and shake well Observations                                      Inferences (2 marks)

d). Warm the fourth portion slightly and add a little solid G, sodium hydrogen carbonate observations                                         inferences (2 marks)

OCTOBER / NOVEMBER 2002

1.                You are provided with the following;

• Hydrogen peroxide labeled solution A
• Dilute sulphuric acid labeled solution B

 

• Sodium thiosulphate labeled solution C
• Potassium iodide labeled solution D
• Starch solution labeled solution E
• Distilled water in a wash bottle

 

You are required to determine how the rate of reaction of hydrogen peroxide with potassium iodide varies with the concentration of hydrogen peroxide.

 

Procedure Experiment I.

Label two 200ml or 250ml beakers as beaker 1 and beaker 2.

Using a burette, place 25.0cm³ of solution A into beaker 1. Into the same beaker, add 20cm³ of solution B using a 50ml or 100ml measuring cylinder. Shake the contents of beaker 1.

 

Using a 10ml measuring cylinder, place 5cm³ of solution C into beaker 2 followed by 5cm³ of solution D then 2cm³ of solution E. shake the contents of beaker 2. Pour the contents of beaker 2 into beaker 1 and start a stop clock/watch immediately. Swirl the mixture and let it stand. Note the time taken for the blue colour to appear. Record the time in the space provided for experiment 1 in the table below.

 

Clean beaker 1. Repeat the procedure with the volumes of water below. Clean beaker 1. Repeat the procedure with the volumes of water, solutions A, B, C, D and E as shown in the table for experiments 2 to 5.

Complete the table by computing   1     sec ^-1                               7 ½ marks)

Time

a).

	BEAKER 1			BEAKER 2
Experiment	Volume of water (cm3)	Volume of hydrogen peroxide, solution A (cm3)	Volume of dilute sulphuric acid, solution B (cm3)	Volume of sodium thiosulphate, solution C (cm3)	Volume of potassium iodide, solution D (cm3)	Volume of starch, solution E (cm3)	Time (sec)	1 Time sec -1
1	0	25	20	5	5	2
2	5	20	20	5	5	2
3	10	15	20	5	5	2
4	15	10	20	5	5	2
5	20	5	20	5	5	2

 

• Plot a graph of (¹/time) sec ^-1 (y-axis) against volume of hydrogen peroxide used (solution A). (4 marks)
• From your graph determine the time that would be taken if the contents of beaker 1 were 5cm³ water 7.5cm³ solution A and 20cm³ solution B.

(2 marks)

• How does the rate of reaction of hydrogen peroxide with potassium iodide vary with the concentration of hydrogen peroxide (2 marks)

 

2. You are provided with solution F, solid G and sodium sulphate Carry out the tests below. Write your observations and inferences in the spaces provided. a). Place 10cm³ of solution F in a boiling tube. Add all of solid G to solution F

at once. Warm the mixture for one minute then shake vigorously for about five minutes. Filter the mixture into a test-tube and use the filtrate for tests

(b) to (e) below.

Observations                                                                                Inferences

 

(1 mark)                                                                   (1 mark)

• To 2cm³ of the filtrate in a test–tube, add five drops of barium nitrate solution

Observations                                                                                Inferences

 

 

• To 2cm³ of the filtrate in a test–tube, drop wise of aqueous sodium hydroxide dropwise until in excess solution

Observations                                                                                Inferences

 

(1 mark)                                                                   (1 mark)

 

• To 2cm³ of the filtrate in a test–tube, add five drops of 2M hydrochloric acid and warm the mixture to boiling

Observations                                                                                Inferences

 

(1 ½ marks)                                                               (1 mark)

• To the remaining filtrate, add 5cm³ of the sodium sulphate solution provided then filter into a clean test-tube using a clean Retain the filtrate for test (f) below.

Observations                                                                                Inferences

(1 mark)                                                                   (1 mark)

• To 2cm³ of the filtrate obtained in (e) above, add aqueous ammonia dropwise until in excess

Observations                                                                                Inferences

 

(2 marks)                                                                  (1 mark)

 

3. You are provided with solid Carry out the tests below. Write your observations and inferences in the spaces provided.

• Using a clean metallic spatula, heat about one third of solid H in a Bunsen burner

 

		Observations	Inferences
47	Chemistry Practical Study Pack                 1989 – 2016

 

(2 marks)                                                                  (1 mark)

 

• Dissolve the remaining portion of solid H into about 10cm³ of distilled water and divide the solution into 3
  • To the first portion, add two drops of acidified potassium permanganate solution

Observations                                                                      Inferences

 

(1 mark)                                                         (1 mark)

• To the second portion, add two drops of bromine water Observations Inferences

 

(1 mark)                                                         (1 mark)

• Determine the pH of the third portion using universal indicator paper

Observations                                                                      Inferences

 

(1 mark)                                                         (1 mark)

 

OCTOBER / NOVEMBER 2003

1. You are provided with solution P and Q.
   • Solution P is acidified potassium permanganate (the same solution will be used for question 3)
   • Solution Q was prepared by dissolving 18g of solid Q in distilled water to make 250cm³ of solution.

You are required to determine the number of moles of Q that react with one mole of potassium permanganate.

 

Procedure

Place the solution P in a burette. Pipette 25cm³ of solution Q into a 250cm³ conical flask. Titrate solution Q with solution P until a permanent pink colour just appears. Record your results in table I below. Repeat the above procedure two more times.

 

a).      Table I

	I	II	III
Final burette reading
Initial burette reading
Volume of solution P (cm3)

(4 marks) b).          Calculate the average volume of solution P used.          (1 mark)

• Given that the concentration of solution P is 0.02M, calculate the number of moles of potassium permanganate (2 marks)

 

• Calculate the concentration of solution Q in moles per (Relative formula mass of Q is 278) (2 marks)
• Calculate the number of moles of Q:
  25. In 0cm³ of solution. (2 marks)
  26. Which react with one mole of potassium permanganate?

(1 mark)

2.                You are provided with:

• 1.9gof solid S. solid S is a dibasic acid, H2A
• 5M solution of the dibasic acid H2A solution T
• Sodium hydroxide, solution

 

You are required to determine:

1. i) The molar heat of solution of solid
2. ii) The heat of reaction of one mole of the dibasic acid with sodium
3. Calculate the heat of reaction of solid H2A with aqueous sodium

 

Procedure 1

Place 30cm³ of distilled water into a 100ml beaker. Measure the initial temperature of the water and record it in the table II below. Add the entire solid S at once. Stir the mixture carefully with the thermometer until all the solid dissolves. Measure the final temperature reached and record it in the table II.

 

Table II a).

Final temperature(0C)
Initial temperature(0C)

(1½ marks) b). Determine the change in temperature, ∆T1                       (½ mark)

Calculate the:

c). i).       Heat change when H2A dissolves in water .assume the heat capacity of the solution is 4.2jg^-10c^-1 and density is 1g/cm³                                                                          (2 marks)

• Number of moles of the acid that were (Relative formula mass of H2A is 126. (1 mark)
• Molarheat of solution H1 solution of the acid H2     (1 mark)

 

Procedure II

Place 30cm³ of solution T into 100ml beaker. Measure the initial temperature and record

it in the Table III below. Measure 30cm³ of sodium hydroxide, solution R. Add al the 30cm³ of solution R at Once to the solution in the beaker.

 

Stir the mixture with the thermometer. Measure the final temperature and record it in Table III.

 

TABLE III

 

a).

Final temperature (OC)
Initial temperature (OC)

 

• Determine the change in temperature ∆T2 c). Determine the:
  4. Heat change for the reaction (assume the heart capacity of the solution is 2jg^{-1 0}C^-1 and density is 1g/cm³) (2 marks)
• Number of moles of the acid H2A (1 mark)
• Heat of reaction H2 of one mole of the acid H2A with sodium

(1 mark)

 

d).      Given that

Water

 

∆H1 is the heat for the reaction H2A(s)                      2H⁺(a(aq)+A^2-(aq)

 

∆H2 is the heat for the reaction 2H+(aq) + 2OH-(aq)                                                                                                                                    2H2O(l) Calculate ∆H3 for the reaction H2A(s)+2OH^–(aq)                                                                                                                      2H2O(l)=A2-(aq)

 

 

 

 

 

 

 

3. You are provided with solid Carry out tests below. Write your observations and inference in the Spaces provided.

 

 

 

 

 

 

 

 

 

 

 

OCTOBER / NOVEMBER 2004

1.                You are provided with:

• Magnesium ribbon, solid A
• 0.7M hydrochloric acid, solution B
• 3M sodium hydroxide, solution C
• Distilled

 

You are required to determine the:

i).       Temperature change when magnesium reacts with excess hydrochloric acid. ii).         Number of moles of hydrochloric acid that remain unreacted

• Number of moles of magnesium that reacted
• Molar heat of reaction between magnesium and hydrochloric acid

 

Procedure I

Using a burette, measure 50cm³ of solution B and place it in a 100 ml beaker. Measure the temperature of solution B in the 100ml beaker and record the value in table 1. Put the magnesium ribbon in the 50cm³ of solution B in the 100ml beaker immediately, start a stop Clock or watch. Stir the mixture continuously with the thermometer making sure that the Magnesium ribbon remains inside the solution as it reacts. Measure the temperature after Every 30 seconds and record the values in table1. Continue stirring and measuring the temperature to complete table 1.

 

Keep the resulting solution for use in procedure 2 Table 1

(a)

Time (sec)	0	30	60	90	120	150	180	210	240	270	300
Temperature (0C)

(5 marks)

• Plot a graph of temperature (y-axis) against time on the grid provided

(3 marks)

• On the  graph,  show  the  maximum  change  in  temperature,  ∆T,  and determine its Value of ∆T      (1 mark)

 

Procedure 2

Transfer all the solution obtained in 1 into a 250ml. conical flask. Clean the burette and use it to place 50cm³ of distilled water into the beaker used in procedure 1. Transfer al the 50cm³ of water into the 250ml conical flask containing the solution from procedure1. Label this as solution D. empty the burette and fill it with solution C. Pipette 25cm³ of solution D and place it into an empty 250ml conical flask. Add two drops of phenolphthalein indicator and titrate solution C against D. Record the results in table two. Repeat the titration of solution C against solution D and complete the table 2

 

b).              Table 2

	I	II	III
Final burette reading
Initial burette reading
Volume of solution C used (cm3)

(4 marks)

 

i).   Calculate the average volume of solution C used                                                                                    (1 mark) ii). Calculate the number of moles of:

I         0.3M sodium hydroxide used                                                                                                  (1 mark) II        Hydrochloric acid in 25cm³ of solution D                                                                          (1 mark)

III       Hydrochloric acid in 100cm³ of solution D                                                                           (1 mark) IV      hydrochloric acid in 50cm³ of solution B                                                                           (1 mark) V   hydrochloric acid that reacted with magnesium                                                                           (1 mark) VI      magnesium that reacted                                                                           (2 marks)

 

• Using your answer in VI above, determine the molar heat of reaction between magnesium and hydrochloric acid (assume the heat capacity of the solution is

4.2 jg^-1deg^-1 and density is 1.0g/cm³

 

2        a).      You are provided with solution H, carry out the tests below. Record

your observation and inferences in the spaces provided. Place 3cm³ of the solution H in the boiling tube. Add 12cm³ of distilled water and shake.

 

Retain the remainder of solution H for use in 2(b).

 

• Use about 2cm³ portions of diluted solution H for tests I and

 

1. To the first portion ,add drop wise about 1cm³ of sodium hydroxide

Observations                                                  Inferences

 

( 2 marks)

1. To the second portion, add 2 to 3 drops of barium chloride Solution

Observations                                                  Inferences

(2 marks)

 

 

• To 3cm³ of the diluted solution H, add drop wise all the chlorine water (source of chlorine) provided

Observations                                                   Inferences

 

(2 marks)

• To 2cm³ the diluted solution H, add all the bromine water (source of bromine)

Observations                                                   Inferences

 

( 2 marks)

• To 2cm³ of the diluted solution H, add 2 or 3 drops of lead (II) nitrate solution

Observations                                                   Inferences

 

(2 marks)

 

 

b).          You are provided with;

• Solution E containing barium ions
• Solution F containing potassium ions
• Solution G containing sodium ions

 

Carry out the tests on solutions E, F, G and H in order to identify the cation present in the solution H.

 

Procedure

Clean one end of glass rod thoroughly. Dip the clean end of the glass rod in solution E.

 

Remove the end and heat it in the non-luminous part of the Bunsen burner flame. Note the colour of the flame and record it in table 3. Allow the glass rod to cool for about two minutes. Repeat the procedure with solutions F, G and H complete the table 3.

 

Table 3 i).

Solution	Colour of the flame
E
F
G
H

 

• Identify the cation present in solution

 

 

 

 

OCTOBER / NOVEMBER 2005

 

1.                You are provided with solid M in the test tube

• You are required to determine the freezing point of solid

 

Procedure

Place 150cm³ of tap water in a 200ml or 250ml, beaker. Heat the water to near boiling. Using a test tube holder, immerse the test tube containing solid M into hot water (ensure that half of the test tube is immersed in water) continue heating the water until the solid starts to melt. insert a thermometer into the liquid being formed in the test tube and note the temperature when all the solid has just melted. Record the temperatures in table 1. Remove the test tube from the water and immediately start the stopwatch clock /watch and record the temperature of the contents of the test tube after every half a minute and complete the table. Dip the thermometer into the hot bath to clean it then wipe it with tissue paper.

 

Table 1

 

Time (Min)	0	½	1	1 ½	2	2 ½	3	3 ½
Temperature (0C)

 

• On the grid provided on page 3, plot a graph of time(Horizontal axis) against

 

• From the graph determine the freezing point of solid M (1 mark)

 

2. You are provided with:

 

• Sodium hydroxide solution Labeled K
• Solution L, containing 60.0g of acid L per litre of solution

You are required to determine the relative formula mass of acid L Procedure

Using a burette, transfer 25.0cm³ of solution K into a 100ml beaker. Measure the

temperature T1 of the solution K and record it in table 2. Pipette 25.0 cm³ of solution L into another 100ml beaker. Measure the temperature T2, of solution L and record it in table two add all the solution K at once to solution L. Stir carefully with the thermometer. Measure the highest temperature, T3 of the mixture and record it in table 2. Repeat the procedure and complete table 2.

 

TABLE 2

 

	I	II
Initial temperature of solution K T1(0C)
Initial temperature of solution L t2(0C)
Highest temperature of mixture T3 (0C)
Average initial temperature (0C)
Change in temperature ∆T (0C)

(5 marks)

Calculate the

• Average T value. (1 mark)
• Heat change for reaction

(Assume density of solution is 1g/cm³ and the specific heat capacity is 4.2jg^-1K^-1)

(2 marks)

• Number of moles of acid L used given that the heat change for the one mole of acid L reacting with sodium hydroxide solution is 4Kj.

(2 marks)

• Concentration of acid L in moles per (2 marks)
• Relative formula mass of acid L (2 marks)

 

3. (a) You are provided with solid N. Carry out the tests Write your observations and inferences in the spaces provided.

 

 

 

b).      You are provided with solid Q. Carry out the tests below. Write your observation and inferences in the spaces provided.

 

OCTOBER / NOVEMBER 2006

1. You are provided with:
   • 5g of solid A in a boiling tube
   • Solution B 06M acidified potassium manganate (VII)

 

You are required to determine:

1. The solubility of solids A at different temperatures
2. The number of moles of water of crystallization in solid A

 

Procedure

• Using a burette add 4cm³ of distilled water to solid A in the boiling tube . Heat the mixture while stirring with the thermometer to about 70⁰c .When all the solid has dissolved allow the solution to cool while stirring with the Note the temperature at which crystals of solid A first appear. Record this temperature in table 1.

 

• Using the burette, add 2cm³ of distilled water to the contents of the boiling tube warm the mixture while stirring with the thermometer until all the solid Allow the mixture to cool while stirring. Note and record the temperature at which crystals of solid A first appear.

 

• Repeat procedure (b) two more times and record the temperature in the table

Retain the contents of the boiling tube for use in the procedure (e).

 

• i). Complete table 1 by calculating the solubility of solid A at the different The solubility of a substance is the mass of that

substance                         that dissolves in 100cm³ (100g) of water at a particular temperature.

Table 1

Volume of water in the boiling tube (cm3)	Temperature   at                       which crystals of solid A first appear (0C)	Solubility   of    solid                  A (g/100 g water)
4
6
8
10

 

• On the grid provided, plot a graph of solubility of solid A (vertical axis) against
• Using your  graph,  determine  the  temperature  at  which  100g  of  solid A would dissolve in 100cm³ of                                                                                     (1 mark)

 

1. e) i). Transfer the contents of the boiling tube into a 250ml volumetric flask,

 

rinse both the boiling tube and the thermometer with distilled water and      add to the volumetric flask. Add more distilled water to make up to the          mark. Label this solution A. fill a burette with solution B. Using the

pipette and pipette filter, place 25.0cm³ of solution A into a

conical flask.                              Warm the mixture to about 60⁰C. Titrate the hot solution A with solution

B until a permanent pink colour persists. Record your readings in table 2.

Repeat the titration two more times and complete the table2. (Retain the remaining solution B for use in question 3 (b) (i)

Table 2

	I	II	III
Final burette reading
Initial burette reading
Volume of solution B used (cm3)

 

• Calculate the:
  1. average volume of solution b used (1 mark)
  2. Number of moles of potassium manganate (VII) used (1 mark)

• Number of moles of A in 25cm³ of solution A given that 2 moles of potassium manganate (VII) react completely with 5 moles of A (1 mark)

1. Relative formula mass of A, (1 mark)

• The formula of A has the form D.XH2 Determine the value of x in the formula given that the relative mass of D is 90.0 and atomic masses of oxygen and hydrogen are 16.0 and 1.0 respectively. (2 marks)

 

2. You are provided with the solid E. carry out tests Write your observations

and inferences in the spaces provided.

 

3. You are provided with solid

Carry out the following tests   and record your observation and inferences in the spaces provided.

 

 

OCTOBER / NOVEMBER 2007

1.                You are provided with;

• Aqueous sulphuric acid labeled solution A
• Solution B containing 0 g per litre of sodium carbonate
• An aqueous solution of substance C labeled solution

 

You are required to determine the; Concentration of solution A

Enthalpy of reaction between sulphuric acid and substance C

 

A.                Procedure

Using a pipette and a pipette filler, place 25.0cm³ of solution A into a 250ml.

 

volumetric flask. Add distilled water to make 250cm³ of solution. Label this solution D.

 

Place solution D in a burette. Clean the pipette and use it to place 25.0cm³ of solution B into a conical flask. Add 2 drops of methyl orange indicator provided and titrate with solution D. record your results in table 1. Repeat the titration two more times and complete the table.

 

Table 1

Final burette reading
Initial burette reading
Volume of solution D used (cm3)

(3 marks)

Calculate;

i).       Average volume of solution D used          (1 mark) ii).          Concentration of sodium carbonate in solution B

(Na=23; 0; O=16; 0, C= 12.0)                                                      (1 mark)

• Concentration of sulphuric acid in solution D (2 marks)
• Concentration of sulphuric acid in solution A (1 mark)

 

B.                Procedure

Label six test-tubes as 1, 2,3,4,5 and 6. Empty the burette and fill it with solution

1. From the burette, place 2cm³ of solution A into test-tube number 1. From the same burette, place 4 cm³ of solution A in test-tube number 2. Repeat the process for test-tube numbers 3, 4, 5 and 6 as shown in table 2.

 

Clean the burette and fill it with solution C. From the burette, place 14cm³ of solution C into a boiling tube. Measure the initial temperature of solution C to                                                                                                        the nearest 0.5⁰C and record it table 2. Add the contest of test-tube number 1 to                                                                                                        the boiling tube containing solution C. stirs the mixture with the thermometer. Note                                                                                                                                                                                                          and record the highest temperature reached in table 2. Repeat the process                                                                                                        with                                                                                                                                                                                                                                                                                                                        the other volumes of solution C given in table 2 and complete the table.

 

Table 2

Test-tube number	1	2	3	4	5	6
Volume of solution A(cm3)	2	4	6	8	10	12
Volume of solution C(cm3)	14	12	10	8	6	4
Initial temperature of solution C(0C)
Highest temperature of solution C(0C)
Change in temperature ∆T(0C)

 

(6 marks)

• On the grid provided, draw a graph of ∆T (vertical axis) against volume of solution A used (3 marks)
• From the graph, determine;
  1. The maximum change in temperature (1 mark)

 

1. The volume of solution A required to give the maximum change in temperature                             (1 mark)

• Calculate the;
  1. Number of moles of sulphuric acid required to give the maximum change in temperature (1 mark)
  2. Molar enthalpy of reaction between sulphuric acid and substance C (in kilojoules per mole of sulphuric acid).

Assume the specific heat capacity of the solution is 4.2jg^-1 K^-1 and density of solution is 1.0 gcm^-3.             (2 marks)

 

2. You are provided with solid Carry out the tests below. Write your observations and inferences in the spaces provided.

 

a).	Place one half of solid E in a clean dry test-tube and heat it strongly. Test any gases produced with blue and red litmus papers. Observations                                                    inferences   (2 marks)                                                          (1 mark)
b).	Place the other half of solid E in a boiling tube. Add about 10cm3 of
	distilled water and shake until all the solid dissolves. (Use the solution
	for tests (i), (ii), (iii) and (iv).
i).	Place two or three drops of the solution in a test-tube. Add 3cm3 of
	distilled water. Add two drops of universal indicator to the mixture
	obtained and then determine the pH of the mixture
	Observations                                                     inferences
	(1 mark)                                                            (1 mark)
ii).	To about 1cm3 of the solution a test–tube, add aqueous ammonia drop– wise until in excess Observations                                                      inferences   (1 mark)                                                             (1 mark)
iii).	To  2cm3 of  the  solution  in  a  test-tube,  add  three  or  four  drops  of solution G (aqueous potassium iodide) Observations                                                    inferences   (1 mark)                                                              (1 mark)
iv).	To about 1cm3 of the solution a test–tube, add four or five drops of barium nitrate solution. Shake the mixture then add about 1cm3 of dilute nitric acid and allow the mixture to stand for about 2 minutes. Observations                                                       inferences   (1 mark)                                                    (1 mark)

 

3. You are provided with liquid carry out the tests below. Record your observations and inferences in the spaces provided.

a).	Place three or four drops of liquid F on watch glass. Ignite the liquid using a Bunsen burner Observations                                                      inferences   (1 mark)                                                             (1 mark)
b).	To 1cm3 of liquid F in a test–tube, add about 1cm3 of distilled water and shake thoroughly. Observations                                                    inferences (1 mark)                                                             (1 mark)
c).	To 1cm3 of liquid F in a test–tube, add a small amount of solid sodium carbonate Observations                                                    inferences   (1 mark)                                                 (1 mark)
d).	To  2cm3  of  liquid  F  in  a  test-tube,  add  about  1cm3  of  solution  H (acidified potassium dichromate (VI). Warm the mixture gently and allow it to stand for about one minute of distilled water and shake thoroughly. Observations                                                    inferences   (1 mark)                                                              (1 mark)

 

OCTOBER / NOVEMBER 2008

1. You are provided with:
   • Solid A
   • M hydrochloric acid, solution B
   • 1M sodium hydroxide

 

You are required to determine the enthalpy change ∆H, for the reaction between solid A and one mole of hydrochloric acid.

 

Procedure A

Using a burette, place 20.0cm³ of 2.0M hydrochloric acid, solution B in a 100ml.  Beaker. Measure the temperature of the solution after every half-minute and record the values in table 1. At exactly 2 ½ minutes, add all of solid A to the acid. Stir the mixture gently with the thermometer. Measure the temperature of the mixture after every half-minute and record the values in table 1. (Retain the mixture for use in procedure B).

 

Table 1.

 

Time (min)	0	½	1	1 ½	2	2 ½	3	3 ½	4	4 ½	5
Tem (0C)

(4 marks)

 

i).    Plot a graph of temperature (Y= axis) against time                                                                                     (3 marks) ii).      Using the graph, determine the change in temperature ∆T     (1 mark)

iii). Calculate the heat change for the reaction (assume that the specific heat capacity of the mixture is 4.2jg^-1K^-1 and the density of the mixture is 1g/cm³                                                                       (2marks)

 

Procedure B

Rinse the burette thoroughly and fill it with sodium hydroxide. Transfer all the contents of the 100ml. beaker used in procedure A into a 250ml. volumetric flask. Add distilled water to make up to the mark. Label this solution C. Using a pipette and a pipette filler, place indicator and titrate against sodium hydroxide. Record your results in table 2. Repeat titration two more times and complete table 2.

 

Table 2

	I	II	III
Final burette reading
Initial burette reading
Titre (cm3)

 

Calculate the:

• Average volume of sodium hydroxide used (1 mark) ii).          The number of moles of
  1. Sodium hydroxide used (1 mark)
  2. Hydroxide acid in 25cm³ of solution C (1 mark)

• Hydrochloric acid in 250cm³ of solution C (1 mark)

20. Hydrochloric acid in 0cm³ of solution B (1 mark)
21. Hydrochloric acid that reacted with solid A (1 mark)

 

iii).     Calculate the enthalpy of reaction between solid A and one mole of hydrochloric acid (show the sign ∆H)                                                                                        (2 marks)

 

 

 

 

2. You are provided with solid D. Carry out the tests Write your observations and inferences in the spaces provided.

 

	until no further change occurs. Test any gases produced with both blue and red litmus papers. Allow the residue to cool and use it for test (b). Observations                                                       inferences   (2 marks)                                            (1 mark)
b).	Add about 10cm3 of 2M hydrochloric acid to the residue and shake for about three minutes. Keep the mixture for test (c) Observations                                                      inferences   (1 mark)                                              (1 mark)
c). i).	Place about 1cm3 of the mixture in a test-tube and add aqueous ammonia dropwise until in excess Observations                                                    inferences   (1 mark)                                               (1 mark)
ii).	To the rest of the mixture, add all of solid E provided and shake the mixture well. Observations                                                    inferences   (1 mark)                                              (1 mark)

 

3. You are provided with solid F. Carry out the tests below. Write your observations and inferences in the spaces provided

 

a).	Place about one third of solid F on a metallic spatula and burn it using a Bunsen burner Observations                                                  inferences   ( ½ mark)                                             ( ½ mark)
b).	Place the remaining of solid F in a test-tube. Add about 6cm3 of distilled water and shake the mixture well. (Retain the mixture for use in test (c) Observations                                                    inferences   (1 mark)                                                  (1 mark)
c). i).	To about 2cm3 of the mixture, add a small amount of solid sodium hydrogen carbonate Observations                                                                           inferences   (1 mark)                                                    (1 mark)
ii).	To about 1cm3 of the mixture, add 1cm3 of acidified potassium

 

	dichromate (VI) and warm Observations                                                                             inferences   (1 mark)                                                  (1 mark)
iii).	To about 2cm3 of the mixture, add two drops of acidifies potassium manganate (VII) Observations                                                                                inferences   (1 mark)                                              (1 mark)

 

 

OCTOBER / NOVEMBER 2009

1.                You are provided with;

• SolidA, a metal carbonate M2CO3
• Solution B, hydrochloric acid for use in question 1 and 2
• Solution, C 0.3M sodium hydroxide
• Methyl orange indicator

 

You are required to:

Prepare a dilute solution of hydrochloric acid and determine its concentration Determine the solubility of solid A in water

 

Procedure I

Dry conical flask for use in step 4)

 

Step 1   Place all of solid A in a 250ml dry beaker. Add 100cm³ of distilled water to solid A in the beaker. Using a glass rod, stir the mixture thoroughly for about two minutes. Leave the mixture to stand and proceed with steps 2 and 3.

 

Step 2   Using a pipette filler, place 25.0cm³ of solution B in a 250ml volumetric flask. Add about 200cm³ of distilled water. Shake the mixture well and add distilled water to make up to the mark. Label this as solution D.

 

Step 3 Fill a burette with solution C. Using a pipette and pipette filler, place 25.0cm³ of solution D into a 250ml conical flask. Add two drops of the indicator provided and titrate solution D with solution C. Record your results in table 1. Repeat the titration two more times and complete the table 1. Retain the remaining solution D for use in step 5.

 

Step 4          Filter the mixture obtained in step 1 using filter funnel into a dry conical flask. Lable the filtrate as solution

 

Step 5   Clean the burette and fill it with solution D. using a pipette and a pipette filler, place 25.0cm³ of solution A into a 250ml conical flask. Add two drops of the indicator provided and titrate solution with solution D. record your results in table 2. Repeat the titration two more times and complete table 2.

 

Table 1

	I	II	III
Final burette reading
Initial burette reading
Volume of solution C used (cm3)

 

• Calculate;
  • The average volume of solution C
  • Moles of sodium hydroxide in the average volume of solution C used
  • Moles of hydrochloric acid in 0cm³ of solution D iv). The morality of hydrochloric acid, solution D

 

Table 2

	I	II	III
Final burette reading
Initial burette reading
Volume of solution D used (cm3)

 

• Calculate;
• The average volume of solution D used
• Moles of hydrochloric acid in the average volume of solution D used
• Moles of the metal carbonate, solid A in 25.0cm³ of solution A iv). The solubility of the metal carbonate, solid A in water

(Relative formula mass of metal carbonate = 74, assume density of solution =1g/cm³)

2. You are provided with solid Carry out the following tests and write your observations and inferences in the spaces provided.

 

• Place about one-half of solid E in a dry test-tube. Heat it strongly and test any gas produced using hydrochloric acid, solution B on a glass rod.

 

Observations                                                                                Inferences

(2 marks)                                                                  (1 mark)

 

• Place the rest of solid E in a boiling Add about 10cm³ if distilled water. Shake well and use 2cm³ portions for each of the tests below.

 

i).       To one portion, add aqueous ammonia dropwise until in excess

 

Observations                                         Inferences

(1 mark)                                               (1 mark)

ii¬).    To a second portion, add about 1cm³ of hydrochloric acid solution B.

Observations                                         Inferences

 

(1 mark)                                               (1 mark)

iii).     To a third portion, add two drops of aqueous lead (II) nitrate and heat the mixture to boiling;

 

Observations                                         Inferences

(1 mark)                                               (1 mark)

 

3. You are provide with solid F. Carry out the following tests and record your observations and inferences in the spaces

• Place about one half of solid F in a dry test-tube. Retain the other half of solid F for use in (b). Add all of the absolute ethanol provided to solid F in the test-tube. Shake the

 

Observations                                         Inferences

(1 mark)                                               (1 mark)

 

Divide the mixture into two portions

• Determine the PH of the first portion using universal indicator solution and

PH chart.

 

Observations                                                   Inferences

(1 mark)                                                         (1 mark)

• To the second portion, add one half of the solid sodium hydrogen carbonate

Observations                                         Inferences

(1 mark)                                                                   (1 mark)

 

• Place the remaining amount of solid F in a boiling tube. Add 10cm³ of distilled water and Boil the mixture and divide it into three portions while still warm.
  • To the first portion, add the remaining amount of solid sodium hydrogen

 

Observations                                         Inferences

(1 mark)                                                         (1 mark)

 

• To the second portion, add three drops of acidified potassium

 

dichromate (VI) solution and warm

 

Observations                                                                      Inferences

 

(1 mark)                                                         (1 mark)

 

• To the third portion, add five drops of bromine water Observations Inferences

(1 mark)                                                         (1 mark)

 

OCTOBER /NOVEMBER 2010

1.              You are provided with;

• Acid A labeled solution A
• M sodium hydroxide solution labeled solution B
• Solutions C containing 0 g per litre of an alkanoic acid

 

You are required to:

• Prepare a dilute solution of solution hydroxide, solution B b). Determine the:
  • Molar mass of the alkanoic acid
  • Reaction ratio between sodium hydroxide and acid A

 

Procedure I

Using a pipette and a pipette filler, place 25.0cm³ of solution B into a 250.0ml volumetric flask. Add about 200cm³ of distilled water. Shake well. Add more distilled water to make upto the mark. Label this solution D. Retain the remaining solution B for use in procedure II.

 

Fill a burette with solution C. using a clean pipette and a pipette filler, place 25.0cm³ of solution D into a 250ml conical flask. Add two drops of phenolphthalein indicator and titrate with solution C. record your results in table

 

1. Repeat the titration two more times and complete the

 

Table	1st	2nd	3rd
Final burette reading
Final burette reading
Volume of solution C used (cm3) added

(4 marks)

Determine the:

• Average volume of solution C used (1 mark)
• Concentration of solution D in moles per litre (1 mark) iii).          Concentration of the alkanoic acid in solution C in moles per litre (1 mole

of the acid reacts with 3 moles of the base)                          (1 mark)

 

iv).     Molar mass of the alkanoic acid                                           (1 mark)

 

Procedure II

Fill a clean burette with solution A. place 5cm3 of solution A into a 100ml beaker. Measure the initial temperature of solution A in the beaker record it in table II. Using a 10ml or a 100ml measuring cylinder, measures 25cm³ of solution B. add it to solution A in the beaker and immediately stir the mixture with the thermometer. Record the maximum temperature reached in table II. Repeat the experiment with other sets of volumes of solutions A and B complete the table.

 

Table II

Volume of solution A (cm3)	5	9	13	17	21	25
Volume of solution B (cm3)	25	21	17	13	9	5
Maximum temperature (0C)
Initial temperature (0C)
Change in temperature, ∆T

(6 marks)

1. On the grid provided, plot a graph of ∆T (Vertical axis) against the volume of solution A (3 marks)
2. From the graph, determine the volume of solution A which gave the maximum change in temperature (1 mark)
3. Determine the volume of solution B that reacted with the volume of solution A in (b) above (1 mark)

 

 

1. Calculate the:
   • Ratio between the volumes of solutions A and B that neutralized one (1 mark)
   • Concentration in moles per litre of the acid in solution (assume that the volume ratio is the same as the mole ratio). (1 mark)

 

2.                You are provide with solids E, F and G.

Cary out the tests below and write your observations and inferences in the spaces provided

• Place all of solid E in a boiling Add 20cm³ of distilled water and shake until all the solid dissolves. Label this as solution E.
  • To about 2cm³ of solution E in a test–tube, add 4 drops of 2M sulphuric (VI)

Observations                                                   Inferences

(1 mark)                                               (2 marks)

• To about 2cm³ of solution E in a test–tube, add 2M sodium hydroxide dropwise until in

Observations                                                                      Inferences

(1 mark)                                               (1 mark)

• Place one half of solid F in a test-tube. Add 2cm³ of distilled water

 

and shake well. Add 4 drops of this solution to about 2cm³ of solution E in a test-tube.

Observations                                                                      Inferences

(1 mark)                                               (1 mark)

• To about 2cm³ of solution E in a test tube, add 2 drops of aqueous potassium

Observations                                                                      Inferences

(1mark)                                                (1 mark)

 

1. To about 2cm³ of the solution obtained in (ii) above, add 3 drops acidified potassium manganate (VII).

Observations                                                   Inferences

(1 mark)                                                         (1 mark)

• To about 2cm³ of the solution obtained in (ii) above, add 2 drops of bromine

Observations                                                   Inferences

 

(1 mark)                                                         (1 mark)

1. To the remaining solution G in the boiling tube, add the other half of solid

Observations                                                   Inferences

 

(1 mark)                                                         (1 mark)

OCTOBER /NOVEMBER 2011

 

1. You are provided with:
   • 60g of solid A , dibasic acid
   • Solution B containing 75g per litre of salt B.
   • Aqueous sodium hydroxide, solution
   • Phenolphthalein

 

You are required to prepare a solution of solid A and use it to determine the:-

• Concentration of sodium hydroxide, solution C

• React salt B with excess sodium hydroxide and then determine the relative molecular mass of salt B.

 

Procedure I

• Using a burette, place 0cm³ of solution B in each of two 250ml conical flasks. Using a pipette and a pipette filler, add 25.0cm³ of solution C to each of the two conical flasks. The sodium hydroxide added is in excess). Label the conical flasks 1 and 2.
• Heat the contents of first of the first conical flask to boiling and then let the mixture boil for five Allow the mixture to cool.
• Repeat procedure (b) with second conical flask. While the mixtures are cooling, proceed with procedure II.

 

Procedure II

• Place all solid A in a 250ml volumetric flask. Add about 150cm³ of distilled water, shake well dissolve the solid and then add water to make up to the Label this as solution A.
• Place solution A in a clean Using a pipette and a pipette filler, place 25.0cm³ of solution C in a 250ml conical flask. Add 2 drops of phenolphathein indicator and titrate with solution A. Record your results in Table 1. Repeat the titration two more times and complete the table.

 

Table 1

	I	II	III
Final burette reading
Initial burette reading
Volume of solution A used (cm3)

(4 marks)

 

 

 

Calculate the:

 

• Average volume of solution A used: ( ½ mark)
• Concentration in moles per litre of the dibasic acid in solution A; (Relative molecular mass of A is 126) (2 marks)
• Moles of the dibasic acid used;                                              (1 mark)
• Moles of sodium hydroxide in 0cm³ of solution C. (1 mark)
• Concentration of sodium hydroxide in moles per litre (2 marks) Procedure III

Add 2 drops of phenolphthalein indicator to the contents of the first conical flask prepared in procedure I and titrate with solution A. Record your results in Table 2. Repeat the procedure with the contents of the second conical flask and complete the table.

 

Table 2

	1st Conical flask	2nd Conical Flask
Final burette reading
Initial burette reading
Volume of solution A used (cm3)

(3 marks)

Calculate the: –

• average volume of solution A used; ( ½mark)
• Moles of the dibasic acid used; (1 mark)

 

• Moles of sodium hydroxide that reacted with the basic (1 mark)
• Moles of sodium hydroxide that reacted with 0cm³ of salt B in solution B;

(2 marks)

• Given that 1 mole of salt B reacts with 2 moles of sodium hydroxide . Calculate the : –
  25. Number of moles of salt B in 0cm³ of solution B; ( 1 mark)
  26. Concentration in moles per litre of salt B in solution B ; ( 1 mark)

• Relative molecular mass of salt B; ( 2 marks)

 

2. (a) (i)       You are provided with solid Carry out the following tests and write your observations and inferences in the spaces provided

 

Observations                                                                      Inferences

(2 marks)                                                        (1 mark)

 

 

(ii)      Place the rest of solid D in a boiling tube. Add about 10cm³ of distilled water. Shake well.

 

To  a  2cm³  portion  of  the  solution,  add  about  1cm³  of  hydrogen peroxide and shake well. To the resulting mixture, add aqueous sodium hydroxide drop wise until in excess.

 

Observations                                                                      Inferences

(1 mark)                                                         (1 mark)

 

• You are provided with solution E. Carry out the following tests and write your observations and inferences in the spaces

 

Divide solution E into two observations.

• To one portion of solution E in a test tube, add 3 drops of barium Retain the mixture for use in test (ii) below.

 

Observations                                                                      Inferences

(1 mark)                                                         (2 marks)

 

• To mixture obtained in (i) above, add about 5cm³ of 2M nitric (V) acid

 

Observations                                                                      Inferences

(1 mark)                                                         (1 mark)

 

OCTOBER /NOVEMBER 2012

 

1.                You are provided with:

• Solution A containing an oxidising agent A;
• Solution B, 0.05M aqueous sodium thiosulphate;
• Solution C , containing a reducing agent C;
• Aqueous potassium iodide;
• Solution D, starch

 

You are required to determine the:

• Concentration of solution A
• Rate of reaction between the oxidising agent A and the reducing agent C.

 

 

 

 

Procedure 1

 

1. Using a pipette and a pipette filler, place 25.0cm³ of solution A into a 250ml conical
2. Measure 10cm³ of aqueous potassium iodide and add it to solution A in the conical Shake the mixture. Add 10cm³ of 2M sulphuric (VI) acid to the mixture and shake.
3. Fill a burette with solution B and use it to titrate the mixture in the conical flask until it just turns orange – Add 2cm³ of solution D to the mixture in a conical flask. Shake thoroughly. Continue titrating until the mixture just turns colourless. Record your results in table 1 below.
4. Repeat the procedure and complete table Retain the remainder of solution A and solution D for use in procedure II.

 

Table 1

	I	II	III
Final burette reading
Initial burette reading
Volume of solution B used (cm3)

(4 marks)

 

• Calculate the:
  • Average volume of solution B used; ( 1mark)
  • Number of moles of sodium thiosulphate . ( 1mark)
• Given that one mole of A reacts with six moles of  sodium thiosulphate, calculate the;
  • Number of moles of A that were used; ( 1mark)
  • Concentration of solution A in moles per ( 2marks)

 

Procedure II

 

1. Label six test tubes as 1, 2, 3, 4, 5 and 6 and a place them in test- tube
2. using a clean burette, measure the volumes of distilled water shown n table 2 into the labelled test tubes
3. Using a burette, measure the volumes of solution A shown in table 2 into each of the test tubes
4. Clean the burette and rinse it with about 5cm³ of solution
5. Using the burette, measure 5cm³ of solution C and place it into a 100ml
6. Using a 10ml measuring cylinder, measure 5 cm³ of solution D and add it to the beaker containing solution Shake the mixture
7. Pour the contents of test – tube number 1 to the mixture in the beaker and immediately start a stop watch. Swirl the contents of the beaker. Record the time taken for a blue colour to appear in table

 

8. Repeat steps 5 to 7 using the contents of test- tube numbers 2,3,4,5 and
9. Complete table 2 by computing Rate = 1/Time (S^-1)

 

Table 2

Test-tube number	1	2	3	4	5	6
Volume of distilled water (cm3)	0	2	3	5	6	7
Volume of solution A (cm3)	10	8	7	5	4	3
Time (seconds)
Rate = 1/Time (S-1)

a).      Plot a graph of rate (y-axis) against volume of solution A.          (3 marks) b).          What time would be taken for the blue colour to appear if the experiment

was repeated using 4 cm³ of distilled water and 6 cm³ of solution A?

(2

marks)

 

2. You are provided with solid carry out the experiments below. Write your observations and inferences in the spaces provided.

 

Place all of solid E in a boiling tube. Add 20 cm³ of distilled water and shake until all the solid dissolves, label the solution as solution E. Use solution E for experiments (i) and (ii).

 

• To 2cm³ of solution E, in a test–tube in each of experiments I, II, III and IV, add;
  1. Two drops of aqueous sodium sulphate; Observations Inferences

 

(1 mark)                                               (1 mark)

1. Five drops of aqueous sodium chloride;

Observations                                                            Inferences

 

III.	(1 mark) Two drops of barium nitrate; Observations	(1 mark)   Inferences
IV.	(1 mark) Two drops of lead (II) nitrate; Observations	(1 mark)   Inferences

 

(1 mark)                                               (1 mark)

 

 

• To 2cm³  of  solution  E,  in  a  test-tube,  add  5  drops  of  aqueous sodium Add the piece of aluminium foil provided to the mixture and shake. Warm the mixture and test any gas produced with both blue and red litmus papers.      (1 mark)

 

Observations                                                                      Inferences

(2 marks)                                                        (1 mark)

 

3. You are provided with solid Carry out the following tests. Write your observations and inferences in the spaces provided.

 

• Place all of solid F in a boiling Add about 20 cm³ of distilled water and shake until all the solid dissolves. Label the solution as solution F. Add about half of the solid sodium hydrogen carbonate provided to 2cm³ of solution F.

Observations                                                 Inferences

(1 mark)                                                         (1 mark)

 

• i). Add about 10cm³ of dilute hydrochloric acid to the rest of solution F in the boiling Filter the mixture. Wash the residue with about 2cm³ of distilled water. Dry the residue between filter papers. Place about one third of the dry residue on a metallic spatula and burn it in a Bunsen burner flame

Observations                                                                      Inferences

 

(1 mark)                                                         (1 mark)

ii).      Place all the remaining residue into a boiling tube. Add about 10cm³ of distilled water and shake thoroughly. Retain the mixture for the tests in (C).

Observations                                                                      Inferences

 

(½ mark)                                                          (½ mark)

• Divide the mixture into two portions:
  • To the first portion, add the rest of the solid sodium, hydrogen

 

carbonate

Observations                                                                      Inferences

 

(1 mark)                                                         (1 mark)

 

• To the second portion, add two drops of bromine water Observations Inferences

(1 mark)                                                         (1 mark)

 

OCTOBER / NOVEMBER 2013

 

You are provided with:

• Solution A, aqueous copper (II) sulphate:
• Solid B, iron powder:
• 0.02 m acidified potassium manganate (VII), solution C.
• You are required to determine the molar heat of displacement of copper by

 

Procedure I.

Using a burette, place 50.0cm³ of solution A in a 100ml beaker. Measure

 

PROCEDURE I.

Using a burette, place 50.0cm³ of solution A in a 100 ml beaker. Measure the temperature of the solution and record it in table I below. Add all of solid B provided at once and start a stop watch. Stir the mixture thoroughly with the thermometer and record the temperature of the mixture after every one minute in the table. Retain the mixture for use in procedure II below.

 

Table I.

Time (Min.)	0	1	2	3	4	5	6	7
Temperature (0C)

 

1. a) i). Plot a graph of temperature (vertical axis) against time in the grid

• From the graph, determine the:
  1. Highest change in temperature, △T: (1 mark)
  2. Time taken for reaction to be completed ( ½ mark)

• Calculate the heat change for the (Specific heat capacity of

solution is 4.2Jg-1 K-1; Density of the solution is 1 gcm³).

(2

marks)

 

PROCEDURE II

Carefully decant the mixture obtained in procedure I into a 250ml volumetric flask. Add

 

about 10cm³ of distilled water to the residue in the 100 ml beaker. Shake well, allow the mixture to settle and carefully decant into the volumetric flask. Immediately, add about 50cm³ of 2M sulphuric (VI) acid to the mixture in the volumetric flask. Add more distilled water to make 250.0 cm³ of solution. Label this as solution D.

Fill a burette with solution C. Using a pipette and pipette filler, place 25.0cm³ of solution D into a 250 ml conical flask. Titrate solution D against solution C until the first permanent pink colour is obtained. Record your results in table 2 below. Repeat the titration two more times and complete the table. Retain the remaining solution C for use in question 3.

Table 2

	I	II	III
Final burette reading
Initial burette reading
Volume of solution C used (cm3)

(4 marks)

• Determine the average volume of solution C used (1 mark)
  • Transfer about half of the dry residue into a dry test-tube. Heat the residue strongly and test any gas produced using a burning splint

 

Observations	Inferences
(1 mark)	(1 mark)

 

• Place the rest of the residue in a dry test-tube. Add 4cm³ of 2M hydrochloric Retain the mixture for test (iii) below.

Observations	Inferences
(1 mark)	(1 mark)

 

Observations Inferences   (1 mark)   (1 mark)

• To 2cm³ of the solution obtained in (ii) above, add 6cm³ of aqueous ammonia

 

• i). To 2cm³ of the filtrate

obtained in (a) above, add about 3cm3 of aqueous ammonia (Excess).

Observations	Inferences
(1 mark)	(1 mark)

 

• To 2cm³ of the filtrate, add about 2cm³ of 2M hydrochloric

Observations	Inferences
(1 mark)	(1 mark)

 

• To 2cm³ of the filtrate, add one or two drops of barium nitrate

 

Observations	Inferences
(1 mark)	(1 mark)

 

3. You are provided with solid G. Carry out the tests in (a) and (b) and write your observations and inferences in the spaces Describe the method used in part (c).
   • Place about one third of solid G on a metallic spatula and burn it in a Bunsen burner flame

Observations	Inferences
(1 mark)	(1 mark)

 

• Dissolve all of the remaining solid G in about 10cm³ of distilled water in a boiling Use the solution for tests (b) (i), (ii) and (c).
  • Place 2 cm³ of the solution in a test-tube and add 2 drops of acidified potassium manganate (VII); solution

Observations	Inferences
(1 mark)	(1 mark)

 

• To 2cm³ of the solution, add all of solid sodium hydrogen carbonate

Observations	Inferences
(1 mark)	(1 mark)

 

• Determine the p H of the solution obtained in (b) above

Observations	Inferences
(1 mark)	(1 mark)

 

 

 

 

 

CO-ORDINATED MARK SCHEMES

 

NOVEMBER 1995 MARK SCHEME

 

1.

Time (min)	0	½	1	1 ½	2	2 ½	3	3 ½	4	4 ½	5
Temperature (0C)	23.5	23.5	23.5	23.5	23.5		15.5	16.0	16.5	17.0	17.5

Table I                                                                                                  (3 Marks)

• Complete with 10 readings; if 1^st reading > 40 or <10 then unrealistic (award 0)
• Decimal (D) – ½ – Accept whole numbers and or decimals to d.c.p only c 1^st d.c.p value as 0 or 5 only
• Accuracy – ½ – 1^st reading should be within +2⁰ of school value
• Trends – 1 – (1/2, ½) as i).Readings betweens 0 -2 minutes should be constant (½)

ii).Readings between 3 -5 min should use continuously (½)

 

NB;       Reaction is endothermic hence temperature must drop in minute 3. If not penalize ½ mark

 

 

 

 

 

 

 

 

Temp

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fall in temperature ∆T1=……………. 15 – 0 – 23.5 = – 8.5⁰C

(1 mark)

 

Graph I                                                                                                              (3 Marks)

Scale (sc) – ½ – plots should cover (4 ½ x 3 ½ squares) or more

Plots (Pt) – 1 – if 3 readings incorrect give ½ but if more than 3 incorrect (award 0) If correct scale intervals correct only.

Lines (Lns) – 1 – ½ (for each line) lines should pass through at least three points for each line Xtrapolation (ext) – ½ – for the second line extended downwards

∆ T1 = 1 –          a). show ∆T1 on graph at 2 ½ minute ( ½ mark) b). Ignore sign of ∆T value

 

a).        i).         n1 = ²/100 = 0.02

Penalize ½ mark for wrong units i.e. m or M. Accept figure continuous units.

If wrong RFM used but shown how found, penalize ½ and mark answer if correct (using wrong RFM)

ii).                   Mass of solution x 4.2 x ∆T1

 

∆H1                                       n1 x 1000

-1

Kjmol

 

 

Same as for graph I                                                          For correct substitution of

∆T1 and n1

 

 

Size 3 ½ x 3 ½ sq

 

Correct answer should

Correct answer

 

Be within +2 units correct in the 1^st D.C.P (otherwise penalise ½) Have correct sign (+ve) (otherwise per ½ mark)

Penalized ½ if wrong units used – accept lack of units (on second line only)

1. b) i). n2 =¹/84v           = 0119

= 0. 012

Accept answer to 3 or 4 D.C.P only (Not 2 d.c.p)

If RFM is wrong (but shown it was calculated) Penalize ½ mark and mark answer if

correct using

the wrong RFM

ii). For correct subt of n2 + ∆T2 = Correct answer

Answer should be correct to within 12 units in 1^st D.C.P

Answer should bear correct sign (-ve) otherwise penalize ½ mark Accept units missing otherwise penalize ½ mark for wrong units used.

 

• 1Mark – for correct substitution of ∆H1, ∆H2 and ∆H3 including their respective signs

e.g ∆H4 = 2 (26.8) – (- 43.8) – 2(121)

= – 144.6 kj/mol

1 mark – for correct answer Penalize ½ mark for wrong sign on answer

Award 0 marks for wrong substitution or wrong sign transferred with ∆H in the substitution. Penalise ½ mark for wrong units used

Penalize ½ mark for wrong transfer of any of the ∆H values

 

 

 

 

 

 

9 marks

2 (a)	Silvery / shiny grey/ metallic luster silvery white / shining metal Reject shiny, wrong colour etc, silvery white etc
	Observations	Inferences
(b)	turns black/grey/white	L reacts with oxygen in air to form oxide or L is oxidize
(c)	Effervescence/bubbles/ gas produced / burns with a pop sound	metal L is above hydrogen in the reactivity series/ or mention any metal above H in reactivity series OR just metal up in the series
(d)	Effervescence/bubbles/ gas produced/ gas burns with a pop sound.	metal L is above hydrogen in the reactivity series/ or mention any metal above H in reactivity series OR just metal up in the series
(e)	Black/grey/dark coating OR deposit or ppt or substance	Metal L is above Lead in reactivity series OR Lead is displaced by L

 

9 marks

3 (a)	White Crystalline solid/white powder /white solid
(b)	Burns with Lilac /purple/ violet flame / Reject blue flame
(c)	Gas relights burning splint Solid melts forming colourless liquid If melts to colourless solution (Reject if just melts)	Oxygen/O2 evolved possibly KNO3 Accept NaNO3 if not scored in (b)
(d)(i)	No visible change no effect on litmus paper	Neutral solution
(ii)	No Precipitate / reject no observable change	Zn2+, Al3+, Pb2+, Ca2+, Mg2+ (Any 3 absent) Or K+ , Na+ Present
(iii)	No precipitate.	CO 2-, SO 2- OR Cl– absent 3             4 (Any two mentioned)
(iv)	– Colourless fumes/gas/effervescence which turns moist red litmus blue – Grey / black mixture/solid precipitate	–  NH3 evolved –  Solid contains Nitrogen or NO – ions 3

 

NOVEMBER 1996 MARK SCHEME

 

Principles of averaging

Values averaged must be shown and must be within + 0.20cm³ of each other

 

1. c). Concentration of solution    B = 23.5 Mol^-1 392

= 0.05995 Mol^-1

Note: (i) Accept answer given as 0.060 mol^-1 but reject 0.06 mol^-1

• Units need not be shown but if wrong units are given penalize ½ mk
• Penalise ½ mark for wrong arithmetic

• No of moles of iron (II) ions in 25cm³ of solution B = 25 x in (c)

 

1000

= correct answer

Conditions

• Accept rounding off of answer to 4 p
• penalize ½ mark if answer is rounded off to the 3^rdp iii). If wrong units are given, penalize ½ mark

 

Use of 1^st Principle                                             Use of Formula Method

4

• 5 moles of Fe²⁺ = 1mole of MnO ^– M1V1  = 5

No of moles of A (in litres) used                         M2V2         1

= ¹/5 x ans in (d)

No of moles of A in 1000cm³                 ans (a) x pipette = 5

= ¹/5 x ans in (d) x ¹⁰⁰⁰/titre                                                               M2 x titre                       1

Correct answer             M2 = Ans in © x Pipette

5 x titre

Correct answer

Conditions                                                       Note

• If step 1 not sown but correct a).        If steps (i) and (ii) are not mole ratio used in step 2, credit                                                                                                                        shown but step (iii) and

1 mark                                                              ans are correct

• Penalise ½ mark max 1 ½ marks

for wrong arithmetic                                b).            if step (ii) and (iii)are iii).                       Penalize ½ mark for wrong                                                         combined to make M2

units given                                                        the subject award 1 mark

iv).       Accept rounding of to the                                                                                    for the combined step 3^rd and 4^th d.p

Procedure II

• No of moles of manganate (VII) ions in V2 =          Ans in (e) x Titre

1000

=          correct answer

Conditions

• Accept rounding off of answer to the 4^th p
• Penalise ½ mark if the mark is rounded off to the 3^rdp iii). If wrong units are given, penalize ½ mark

 

4

• 2 moles of MnO ^– ions = 5 moles of dibasic acid

No of moles of the dibasic acid in 25cm³ of sol C = ⁵/2 x ans in (h)

Conditions

• Penalise ½ mark for wrong units used
• Penalise ½ mark for wrong arithmetic if not within 2 units in the 4^th decimal place
• Concentration of the dibasic acid in mol l-1 = Ans in (i) x 1000

Pipette

Conditions

i).         Penalise ½ mark for wrong arithmetic if not within +2 units in the decimal place ii).       Answer should be written to at least 3 decimal places, unless it divides exactly.

Otherwise penalize                                                                      ½ mark

iii).       Penalise ½ mark for wrong units used

 

• RFM of the dibasic acid = 0

ans in (j)                                   ½ mark

= correct answer                                                               ½ mark X + 2 + 36 = RFM of dibasic acid                                                                       ½ mark X + 38 = RFM of dibasic acid                                                             ½ mark Formula mass of X = RFM of dibasic acid – 38                                                                                                               ½ mark

Correct answer

 

	Observations	Inferences
2a (i)	Effervescence that increases with heating Green – yellow gas evolved Gas changes moist blue litmus paper red and then bleaches it	Gas evolved is chlorine D is an oxidizing Agent Note: Chlorine is tied to either greenish – yellow Colour of gas or the Bleaching action of the gas
(ii)	Colourless filtrate obtained brown ppt that is insoluble in excess alkali formed	Fe3+ ions present
b	Effervescence/bubbles/gas evolved gas has no effect on moist litmus paper. Produced gas relights a glowing split	oxygen gas D is a catalyst D is probably     MnO2
Note  In (a) (i) and (b) above credit ½ mark for ’gas’ given in place of effervescence /bubbles  so long as properties of the gas given in the observation column are not contradictory, otherwise no mark for the ‘gas’

3	Observations	Inferences
a)	Melts to a colourless liquid. And burns with a smoky /sooty. Flame Note: accept melts on its own without Mentioning of colourless liquid. Unless contradictory colour given  Accept  –yellow  sooty  flame. But not yellow flame	E is an unsaturated organic compound Note:- credit either E has C: H ratio or E contains C=C or –C=C– in place   of ‘’unsaturated’’ unsaturated tied to smoky flame Organic tied to melting & burning
b)	Solid E does not dissolve readily solid E is sparingly partially soluble /solid E dissolves H+(aq) ions present red.	E is an organic acid E is an acidic compound hydrated hydrogen ions H+(aq) ions present
c)	Solid E dissolved readily in aqueous NaOH	E is organic acid/or E is a carboxylic acid Or Acidic Compound / H+ ions present.
d)(i)	Effervescence/bubbles/ gas evolved colourless gas evolved   extinguishes a burning / glowing Splint changes moist blue litmus paper Faint red / pink	Organic acid or carboxylic aid or Acidic compound/ H+ ions present
(ii)	A    sweet   smelling      substance             is formed / fruity smell/ pleasant smell	Ester is formed                                 O E is a carboxylic acid/ R – COOH / – C – OH alkanoic acid

 

NOVEMBER 1997 MARK SCHEME

 

1. a).

Time (min)	0	½	1	1 ½	2	2 ½	3	3 ½	4	4 ½	5	5 ½	6
Temperature (0C)	20	20	20	X	25	29	31	31	33	34	34	34	34

½ max for each entry Maximum 5 marks

b).        ∆T= 34 – 20 = 14⁰C                                                                                 1 mark

c).        Energy change = 50 x 4.2 x 14 (1)

= 2940 Joules    (1)                                                                                2 marks

d).        Moles = 2940   (1)

 

323 x 1000

= 0.009 moles (1)                                                                     2 marks

 

	I	II	III
Final burette reading (cm3)	32.8	15.9	31.9
Initial burette reading (cm3)	15.8	0.0	16.0
Volume of solution G used (cm3)	17.0	15.9	15.9

 

(6marks)

e).        15.9 + 15.9 ( ½ )

2

= 15.9cm³ ( ½ )                                                                                     1 mark

f).        15.9 x 0.5

1000 (1)

= 0.008 moles (1)                                                                                  2 marks

g).        i).         Moles of sulphuric acid = 0.008

2

= 0.004 moles ( ½ )                               1 mark

ii).        25cm³ = 0.004 ( ½ )

100cm³ = 0.016 moles ( ½ )                                                       1 mark

 

• Total moles of F = 009 + 0.016 (½)

= 0.025 moles ( ½ )                                1 mark

• 50cm³ = 025 moles 1000cm³ = 0.025 x 1000 ( ½ )

50

= 0.5M (½)                                            1 mark

 

2	Observations	Inferences
(a)	Colourless gas that relights a glowing splint (1)is produced	oxide    present    also              allow chlorate                   nitrate, permanganate (1)
(b) (i)	Residue turns black Colourless solution after filtration 1 mark
(ii)	White Ppt (½) Soluble in excess ( ½ )               3 marks	Al 3+ Pb 2+ or Zn2+ (2)
(iii)	White Ppt ( ½ ) insoluble in excess ( ½ )	Pb2+ or Al3– (1)
(iv)	White ppt	Pb2+
3 a)	Decolourise (1)	– C = C   (1) or –OH(1)
b)	Decolourise (1)	– C = C present (1)
c)	Vigorous effervescence (1)	Solid M is an acid or ROOH (1)

 

 

 

NOVEMBER 1998 MARK SCHEME

 

1. Table 1

 

	I	II	III
Final burette reading	25.40	48.00	24.40
Initial burette reading	1.30	24.10	0.40
Volume of solution N(cm3)	24.10	23.90	24.0

1 mark for accuracy; 1 table ; 1 use of decimal; 1 averaging; 1 final

Total marks 4 marks

Average of solution N      =   24.10 + 23.90 + 24.0                                              ( ½ mark)

3

=  24.00cm³                                                                1 mark

a).        Concentration of solution N = 8.8

40            = 0.22M (½)                             1 mark

b).        24.0 x 0.22 = 25M (½)    M = 24 x 0.22

25

= 0.21M (½)                                                      1 mark

Table 2

	I	II	III
Final burette reading	12.50	12.50	29.40
Initial burette reading	0.00	0.0	17.0
Volume of solution N(cm3)	12.50	12.50	12.40

1 mark for accuracy; 1 table ; 1 use of decimal; 1 averaging; 1 final

Total marks 4 marks

Average of solution N= 12.50 + 12.50 + 12.4                                          ( ½ mark)

3

= 12.47cm³ ( ½ )                                               1 mark

i).         12.47 x 0.22 (1)

1000      = 0.00274 moles (1)             2 marks

 

ii).        0. 00274 x 4 ( ½ )

= 0.00100 = ans a (i) x ¹⁰⁰/25                                                                                                                                                                        1 mark

• 21 x 100

1000             = ans (b) x ¹⁰⁰/1000

= -0.021 moles ( ½ ) = ans a (iii)                                                           1 mark

 

iv).       0.02 – 0.0109 ( ½ )

= 0.01 ( ½ )      = ans (ii) – ans (ii)

= ans a (iv)                                                                    1 mark

v).         0.01 ( ½ )      = ans a (i) 2              2

= 0.005 ( ½ )     = ans a (v)                                                                     1 mark

c).        i).         72 x 0.005 ( ½ ) = 0.36g ( ½)

= 72 x ans a (iv) = ans b (i) ii).             0.36 x 100 ( ½ )

0.5

= ans b (i) x 100

0.5

= 72 % ( ½ ) = ans (ii)                                                                           1 mark

 

a).	Observations	Inferences
	Hissing sound White fumes with choking smell that changes Moist blue litmus paper red and red litmus paper remains red	hydrated salt present     (3 marks)

 

	Colourless liquid condenses on cool parts of test tube ( ½ )
i).	white precipitate ( ½ ) soluble in excess ( ½ )	Al 3+ (aq) Pb2+ (aq) or Zn(aq)2+ (2marks) for all three 1 mark for two)                                                                    (3 marks)
ii).	white precipitate ( ½ ) Insoluble in excess ( ½ )	Al3+ ( ½ ) or Pb 2+ ( ½ ) OR Penalise ½ mark each contradiction                                                                    (2 marks)
iii).	No white precipitate (1) Reject no observable change	Absence of SO 2-(aq)   CO 2-(aq)   or SO 2 (aq) (1 mark 4                     3                           3 – for all 3 correct ½ mark for 2 correct)Penalize ½ mark each contradiction. (2 marks)
iv).	White precipitate (1)	Cl(aq) present (2 marks)

 

3.

a).	Observations	Inferences
	Hissing /sound White fumes with choking smell changing moist red litmus blue Melts into a colourless liquid White sublimate Extinguishes a burning splint (2 marks for any four observations correct)	NH + (1) 4 Tied to litmus changing to blue     (3 marks)
b).	i). Turns from colourless to green – yellow OR pH 7 -8	Weekly alkaline (1) Accept neutral (2 marks)
	ii) White precipitate	L is acidic
c)	–  White ppt dissolves on warming –  Effervescence	Carboxylic acid; COOH , H+ Accept acidic compound.

 

NOVEMBER 1999 MARK SCHEME

 

1          (a)        (i)         Table I

Table (T) = 2mks Decimal (D) = 1mk Accuracy (A) = 1mk

Principle of Av (PA) = 1mk Final answer (F) = 1mk

 

Note: – 3 titration consistent = 2mks

2 titration consistent = 1 ½ mks 2 titrations inconsistent 1mk

1 titration done = 1mk

 

(ii)        Average volume of solution E

 

 

 

(b)        (i)         No. of moles of basic compound G2X.10 H2O No. of moles of E = titre x 0.099

1000

No. of moles of F = titre x 0.099 x ½

1000

= Ans (4 d.p)

 

• of solution F in moles per litre 25cm³ of F = Answer in (b) (i) 1000cm³ of F = Ans (b) (I) x 1000

25

= Ans ( 3 dp)

 

• Relative formula mass of basic compound G210 H2O

15.3    =               Molarity (Ans. (b) (ii) RFM

RFM =      15.3                          =          Ans

Ans in (b) (ii)

• Mass of 10 moles of H2O = 10 (16 + 2) = 180 2G + 180 + 155 = Ans (b) (iii)

2G = Ans (b) (iii) – 335 G = Ans (b) (iii) – 335

2

= Ans (± 0.5)

 

2. (a) Table III

T = 5 mks D = ½

A = 1mk (± 5 secs)

T = 1

(b)    (i)    S = 1 mk C = 1 mk P = 1 mk

 

• Showing on the graph = ½ mk Stating correct values ½ mk

Expression t = 1                                                                    = ½ mk

Correct value

Rate at 7.5cm³ (½ mk)

• – Straight line (+ve gradient)                                               = ½ mk

–           Rate of reaction increases as concentration OR

–           Rate is directly proportional to concentration

–           Straight line (+ ve gradient)                                              = ½ mk

 

 

 

 

 

 

 

 

3a).	Observations	Inferences
	–           Light green solid turns brown –           Colourless liquid/moisture/ vapour condenses on cooler part of test tube –         Pungent gas with irritating smell which changes moist blue litmus paper turns red –    Red litmus paper remains 2½mks)	–            Fe2+ present –            Hydrated salt/ water of crystallization
bi).	–     Green precipitate which is insoluble in excess (1mk)	–           Fe2+ present (½ mk)
ii).	Yellow /brown/Reddish brown solution	–           Fe2+ Oxidised to F3+

 

	Brown ppt. Insoluble in excess(1½ marks)
iv)	– White precipitate	– SO 2-, SO 2-, CO 2- 3              4             3
II	– White ppt remains	– SO 2- 4

 

NOVEMBER 2000 MARK SCHEME

 

Table I

• 2 titrations consistent = 1 ½ marks
• 2 titration inconsistent = 1
• 1 titration = 1
• Penalise maximum ( – ½ mark) for wrong amounts > 0 or 1.0cm³

 

Table II

Decimal (D) = ½ mark. Accuracy (A) = ½ mark

• School value ( SV) ± 2 cm³
• If more or less that value = 0

 

(iii)             I           Conc. of Sodium carbonate in moles per litre (RFM Na2CO3 = 106) 5.6    = 0.05283M.

106

Answer given to at least 3 dp. If not, do not award for answer.

Wrong units ½ mark

 

• Moles sodium carbonate in 25cm³ of solution 25 x Ans I = Ans

1000

= 25 x 0.0528

1000

= 0.0013207mol . (at least 4d.p)

 

• Moles of hydrochloric acid in total volume of solution used NaCO3 (aq) + 2 HCl 2NaCl (aq) + H2O + CO2(g)

 

Ans (II) x 2 = Ans.

 

• Concentration of hydrochloric acid in moles per litre Total titre in (a) (ii) = Ans in III

Therefore in 1000cm³ =

 

 

 

Table III

Table (T) = 1 mark

• 8 readings = 1 mk
• 6 readings = ½
• Less than = 0 mk

= Ans III x 1000   =   Ans 3 d.P Total titre

 

• Values > 40⁰C or < 10⁰C ( from t = 0 to t = 1 ½ ) = – ½ mk Decimals (D) = ½ mk

Accuracy (A)

• Compare with school values (SV) at t = 1 ½ if ± 2⁰ c = ½ mk ; If not = 0mk Trend (T) = 1 mark
• Trend – t = 0 to t = 1 ½ being constant = ½ mk OR
• -t = ½ to t 1 ½ being = ½ mk

 

2^nd Trend – t = 2 ½ to t= 4 being constant and lower than between t = 0 to t = 1 ½ = ½ mk.

 

OR

-t = 3 to t = 4 being constant and lower than between t = 0 to t = 1 ½ = ½ mk

 

• The candidate should use the data obtained in table

 

 

 

 

 

∆ T

 

Temp ⁰C

 

 

 

 

 

Time (min)

Scale (S) ½ mk ; Labelling (L) = ½ mk ; Plotting (P) ½ mk ; Shape (S) = ½ mk

 

• See graph in b above of Temperature change ∆ T

 

• (i) of moles of solid G used. (K = 39.0, N = 14.0, O = 16) 1 mark RFM of KNO3 = 101

Moles of G = ³ /101 = 0.0297( 4 d.p)

(ii)        Enthalpy of Solution ∆ Hsoln and show sign of ∆ Hsoln Heat absorbed = 30 x 4.2 x ∆ T = Ans.

Heat absorbed by 1 mole = Ans. Above = Ans J/mol

Ans C

Ans in Kj / mol

 

 

 

 

 

3	Observation	Inferences
(a)	–                            Blue residue /solid ppt (1mk) –                            Colourless filtrate	Cu2+ ions present
(b) (i)	–           White ppt (1mk) –           Dissolves in excess (1mk)
(ii)	–           White ppt (1mk) –           Dissolves in excess (1mk)	Al3+, Zn2+, Pb2+ present
(iii)	–           White ppt (½ mk) –           Insoluble in excess	–  Pb2+ , or Al3+ –  Zn2+ absent
(c)	–           No white precipitate is formed	Al3+ present Pb2+ absent
(d)	–           White Precipitate	SO 2- 4
(e)	–                            Blue precipitate –                         Dissolve in excess to form deep blue solution	– Cu2+ present

 

NOVEMBER 2001 MARK SCHEME

 

1. (a) T = 1mk; AC = 1mk; FA = 1mk, D = 1mk; PA = 1mk

 

• Solution D of NaOH

Moles of HCl                        = Moles of NaOH Molarity                        = titre x 0.128 x 1000

1000 x 25

= Ans

Solution A

Molarity of A = Ans in (a) above x 150

25

= Ans

Or

Ans in (a) above x 6 Procedure II, Table II

 

 

 

 

 

 

∆ T (⁰C)

 

 

 

 

 

 

 

 

 

• From the graph determine the volume of sodium hydroxide, solution A required to neutralize the carboxylic acid
• Calculate the volume of carboxylic acid, solution C used for neutralization (= 20 – Ans (b) above)

(d) (i)         = A:C = Ans (b) : Ans (c) = 2: 1

(ii)        Conc. In moles per litre of the carboxylic acid solution C Moles of A = Ans. b (ii) x Ans (b) above

1000

Moles of C = ½ x moles of A

 

 

Molarity = ½ x Ans. b (ii) x Ans (b) x 1000

1000 x Ans (c)

 

 

2.	Observations	Inferences
(a)	–      Cracking sound –      Colourless liquid forms on cooler	–  Hydrated salt –  Neutral substance

 

	Parts of test tube. – NO effect on both red and blue litmus papers
b(i)	– White precipitate	Ca2+,  Mg2+ or Ba2+ present
(ii)	– White Precipitate	Ca2+,  Mg2+ or Ba2+ present OR Mg2+ absent ½ mark
(iii)	– White precipitate which dissolves on warming	Cl– present

 

3	Observations	Inferences
a	–  Moist blue litmus paper changes to red –  Moist on red litmus paper	– Acidic substance / or H+ present
b	– Brown bromine water is not decolourised	C = C or C = C – absent   OR Saturated compound present ½ C = C or – C = C – absent OR Saturated compound present ½ Alkene / alkyne absent ½
c	Purple or KMnO4 is not decolorized Purple KMnO4 colour persists	Absence of C = C or R – OH absent
d	Effervescence or bubbles of gas OR Fizzing / Hissing sound	Acidic Compound present Or H+ ions

 

 

 

 

 

 

NOVEMBER 2002 MARK SCHEME

 

a).

Vol of A H2O2	Vol. H2O	Vol of B. H2SO4	Vol of C Na2S2O3	Vol of D KI	Vol of E Starch		Time (sec)	1/time sec
25	0	20	5	5	2		18	56×10-2
20	5	20	5	5	2		22.5	4.4×10-2
15	10	20	5	5	2		29	3.4×10-2
10	15	20	5	5	2		43.5	2.3X10-2
5	20	20	5	5	2	90.5	90.5	1.1X10-2

 

b).        ½ for each axis

2 marks for plotting 5p/s correctly

1 mark for best straight line                                                                     4 marks

c).         ¹/time = 1.7 x 10^-2(I)

Time = 58.82sec                                                                                   2 marks

• Rate decreases – with the decrease in the concentration of hydrogen peroxide

2 marks

 

2	Observations	inferences
a	Shiny metal is coated with a Black/grey substance (½)Colourless filtrate obtained (½)	metal G is more reactive than metal whose ions are In solution F (I) OR displacement reaction Occurred
b	No white ppt(1) Or Rej no observable change	Absence of SO 2- CO 2- or SO 2-(ions) 4                  3              3 award 2 marks for all 3 Award 1 mark for 2 Award ½ mark for 1
c	White PPt (½) Soluble in excess (½)	Pb2+, Al3+ or Zn2+ as in (b) above       3 marks
d	White PPt (½) which dissolves on boiling (I)	Pb2+ (I) present 2 ½ marks
e	White PPt (½) colourless filtrate ( ½ )	Pb2+ confirmed (I) 2 marks
f	White PPt (I) Soluble in excess (I)	Zn2+ present (I)    3 marks

 

3	Observations	inferences
a	Melts ( ½ ) into colourless liquid ( ½ ) burns with a smoky flame (1)	unsaturated organic compound accept long chain hydrocarbon or aromatics
b(i)	The purple KMnO4 decolourised/changes to colourless. The colour of KmnO4 changes from purple to colourless (I)                                                  3 marks	Could be an alcohol or unsaturated compound (I) R – OH , – C = C   – C = C –                                2 marks
(ii)	Brown bromine is decolorized/ changes t colourless Decolourised (I)	Unsaturated (I) compound        2 marks
(iii)	Turns orange ( ½ ) pH = 5  ½                                 2 marks	compound is a weak acid (I)      2 marks

 

 

NOVEMBER 2003 MARK SCHEME

 

1. (a) Volume of solution P = 0cm³

(b)        Average volume of solution P 15.0 + 15.0 = 15.0cm³

2

(c)         15.0 x 0.02 = 0.0003 moles

1000

(d)        gdm³ = 4.18 x 1000

250

= 16.72gdm³

16.72 from (d) above = 0.060M 278

(e)        Moles of Q in 25.0cm³

 

0.06 x 25 = 0.0015 moles

1000

 

• 003 moles rxts 0.0015 of Q 1 mole = 1 x 0.0015

0.0003

= 5 moles

 

2. Procedure I
   • Table II Table – ½ mk , Decimal – ½ mk ; Accuracy = ½ mk
   • Final temp – Initial temp
   • (i) Heat change when H2A dissolve in water (assume heat capacity of the solution is 2)

30 x 4.2 x ∆ T = Ans in J. Or 30 x 4.2 x ∆T = kJ

1000

(ii)        Number of moles of acid used (RFM of H2A is 126) 1.9 =           0.01508 moles

126

• Molar heat of solution ∆H1 soln of the acid H2A

 

∆ H c (i) = J/mole Or Kj/mole c (ii)

Procedure II

(a) and (b) as in procedure 1

• (i) Heat (heat capacity 4.2 J/g/⁰C and density 1 g/cm³ 60 x 4.2 x ∆ T = Ans in J or kJ
• Number of moles of the acid H2A used5 x 30 = 0.015

1000

• Heat of reaction ∆ H2 of one mole of the acid H2A with Sodium hydroxide

 

∆ H2  = C (i) = Ans

C (ii)

 

 

Or

60 x 4.2 x ∆ T = Ans. (in J or KJ) C (ii)

 

• ∆ H3 for the reaction H2A (s) + 2 OH^– (aq) 2H2O (l) + A^2- (aq)

∆ H3  = ∆ H2     + ∆ H2   = Ans (-ve kJ /mole)

 

3	Observations	Inferences
(a)	Colourless solution formed	Coloured ions absent  e.g  Cu2+ , Fe2+, or Fe 3+ absent
(b)	No white precipitate formed	Pb2+’ Al3+, Zn2+ , Mg2+  Or Ca2+ absent
(c)	White precipitate formed	Cl–, SO 2–, SO 2– ,  or  CO 2+ present 4             3                       3
(d)	White precipitate formed dissolves in HCl (aq)	SO 2- or CO 2- present 3                    3
(e)	Purple KMnO4 is (aq) decolorized or changes to colourless	SO 2- present Or Reducing 3
(f)	Green solution formed OR Colour changes Orange to green	SO 2- present Or Reducing 3

 

NOVEMBER 2005 MARK SCHEME

 

1. 1. (a)

Time (min)	0	½	1	1 ½	2	2 ½	3	3 ½
Temp (0C)	82	73	69	68	68	68	66	65

 

1 Mark fore the two axis

1 mark for all points correctly plotted

1 mark for plot occupying ¾ of the grid provided

 

• 68⁰C

2

		I	II
Initial temperature of solution KT1 (0C)		26	26
Initial temperature of solution L T2 (0C)		25	26
Highest temperature of mixture T3 (0C)		30.5	31
Average initial temperature (0C)		25.5	26
Change in temperature ∆T (0C)		5	5
	Table 1 ½ mark for each entry	(5 marks)
a).	Average 5 + 5 = 5
	2	(1 mark)
b).	Heat change = 50 x 4.2 x 5 (1)
	= 1050 Joules	(2 marks)

 

 

 

• Number of moles of acid L 1050

143.4 x 1000

= 0.0078125                                                                              (2 marks)

d).        25cm³               = 0.0078125 moles

= 0.0078125 x 1000

25

= 0.3125M                                                    (2 marks)

 

e).        Relative formula mass of acid L 60 = 0.3125 – (L)

R.F.M

R.F.M = 192 (l)

(2 marks)

 

3	Observations	Inferences
(a) (i)	Cracking sound Colourless liquid Gas with pungent smell Colourless gas is produced which changes moist red litmus paper blue (2 marks for four correct observations	N is hydrated a basic gas is formed ( ½ mark for each) (correct inference)
(i)	White Ppt (½)	Al3+ or Pb2+ ions, Mg2+  ions present
(ii)	No white precipitate is formed	Al3+    ion ;      Mg2+   ion present; Pb2+ ions absent
(iii)	White Ppt	SO 2-, SO 2- CO 2-     Cl– 1 mark for two (2 4              3             3 marks)
(iv)	White Ppt

 

	persists (l)	2 SO4  –  ion present  –(l)                (2 marks)
b(i)	A clear colourless solution (l)	Salt is soluble (l)                                                (2 marks) Acid solution is formed ( 1)
(ii)	No effervescence (l)	(H+ absent (l)    (2 marks)
(iii)	White solid formed (l) Slightly soluble in excess ( ½ ) On addition of NaHCO3 There is effervescence ( ½ ) Colourless gas ( ½ ) Give maximum 2 marks for observations) ( 3 marks)	Acid solution is formed ( 1)

 

 

 

 

 

 

 

 

 

NOVEMBER 2006 MARK SCHEME

 

1. Table 1 (i)

Volume of water in the boiling tube (cm3)	Temperature      at                          which crystals of solid A    first appear ( 0C )	Solubility of solid A (g/100g water
4	66 – 67	112.5
6	56 – 57	75
8	49 – 50	56
10	44 – 45	45

1 mark for temp value within range

½ mark for each value ± 2⁰C

½ mark for each value of solubility correctly calculated

(ii)        –           S – 1; P – 1; C – 1

 

(iii)       63 ± 0.5 ⁰C

 

	I	II	III
Final burette reading	24.40	48.60	26.20
Initial burette reading	0.00	24.40	26.40
Volume of solution B used (cm3)	24.40	24.40	24.20

(Award for each titre value ± of the teachers value

I            24.20 + 24.20              =   24.20cm³

2

II           0.06 x 24.20     = 1.45 x 10³ moles

1000

III         1.45 x 10^-3 x 5 = 3.63 x 10^-3 moles

2

 

IV            3.63 x 10^-3 x 10

= 3.63 x 10^-2 moles

= 4.5

x 10^-2

= 124

 

(iii)       DxH2O

90 + 18 x = 124

X = 34

= 1.9

= 2

 

 

 

 

 

 

 

 

 

2.

Observations	Inferences
(a) Colourless liquid condenses on cool parts of test tube. White solid remains	Probably hydrated salt/ compound (1) present
(b)    – Colourless filtrate ( ½ ) – White residue	Compound sparingly soluble
(i)         Solution turns pink	Compound is basic  OH–, HCO3 or CO 2–  present 3 OH– present or HCO3 or CO 2- absent. 3
(ii)        No effervesnce
(iii)       White ppt formed	Ca2+ , Ba2+, Pb2+  present    (2mks for all three 1 mk for 2
(iv)       No white ppt	Ba2+ present or Ca2+ or Pb2+

 

3.

(a) Burns with luminous ( yellow, smoky) flame	Unsaturated    compound         OR     Long                       chain hydrocarbon –     C = C – / – C = C – Or Hydrocarbon with
	high C: H ratio Or aromatic cpd –     NB – Each these tied to burning with smoky/sooty flame
(b) (i) Purple Potassium manganate (VII) is Decolourised (changes from purple to colourless	Alkene or alcohol present –     C = C – or R – OH
(ii) Brown bromine water is decolorized ( Changes from red to Colourless)	Alkene present // – C = C – present

 

 

NOVEMBER 2007 MARK SCHEME

 

1. a).

	I	II	III
Final burette reading	21.8	21.6	43.6
Initial burette reading	0.0	0.0	22.0
Volume of D used (cm3)	21.8	21.6	21.6

(3 marks)

i).         21.6 + 21.6

2                                       =          21.6cm³                        (1 mark)

• F.M of Na2CO3 =             106

Conc.                            8  =  0.075M 106

• Moles of Na2CO3 25 x 075M 1000

=          0.001875

Moles of H2SO4                                            =              0.001875

Conc. of H2SO4                                             =     0.001875 x 1000 21.6

=          0.0868M

 

 

iv).       0.0868 x 10                               =          0.868M

 

Test-tube number 1 2 3 4 5 6 Volume of solution A (cm3) 2 4 6 8 6 4 Volume of solution C (cm3) 14 12 10 8 10 12 Initial temperature of solution C (0C) 20.5 20.5 20.5 20.5 20.5 20.5 Highest temperature of mixture (0C) 23 25.5 28.0 29.5 26.5 24.5 Change in temperature ∆T 2.5 5.0 7.5 9.0 6.5 4.5

b).        i).

(2 marks)

 

(1 mark)

 

 

 

 

 

 

 

ii).	Graph				(3 marks)
iii).	I	∆t = 9.5 + 0.10C			(1 mark)
	II	Maximum volume of A = 7.6cm3 + 0.1
iv).	I	Moles of sulphuric acid = 7.6 x 0.868 1000
II		Heat evolved	=	= 0.0066 moles 16 x 4.2 x 9.5	(1 mark)
		Molar Heat	=     =	638.4 joules = 638.4 0.0066 96.727272KJ mol-1	(2 marks)

 

	2	Observations	Inferences
	(a)	Gas with pungent/irritating/choking smell is produced which changes moist blue litmus paper turns red Colourless liquid formed on cool part of test tube Solid turns reddish brown	hydrated salt acidic gas evolved
	(b) (i (ii)	Reddish brown solution pH 1, 2, 3 Brown precipitate insoluble in excess Brown /Black solid formed or solution	strongly acidic Fe3+
97	Chemistry Practical Study Pack                 1989 – 2016

 

(iii) (iv)

Changes from yellow to brown White precipitate settles at the bottom of the test tube

Iodide ions/ I– ions present

 

3	Observations	Inferences
(a)	Clear blue flame	saturated low carbon organic compound ( 2marks)
(b)	No separation or forms a solution two liquids are miscible	Mixture is miscible or polar organic compound (1 mark)
(c)	No effervescence	Liquid not acidic or absence of H+   (2 marks)
(d)	Solution changes from orange to green	F is likely to be Alcohol or R-OH (2 marks)

 

NOVEMBER 2008 MARK SCHEME

 

1. PROCEDURE

 

TABLE 1                                                                                                                       (4 Marks)

 

Award a total of 4 marks distributed as follows

 

• Complete table (1mark)
• Table with 10 readings (1mark)

 

• Penalties
  • Penalize ½ km once for any space not filled subject to at least 5 readings being given otherwise penalize fully
  • Penalize ½ mark for unrealistic temperature reading (i.e. from t=o min to t =2m if reading of T40⁰C or T> 40^OC ) for the whole table
  • If temperature reading are all constant from t=o to t=5 min penalize ½ mark on complete table
  • Penalise ½ mark on complete table if temperature reading at t=30min is either the same on greater higher than the temperature reading at t=2 min
  • If 2 or more rows of temperature reading are given, penalize ½ mark on complete table and mark table based on the row used to plot the graph. However, if the graph is not drawn then mark the first row of

 

• Use of decimals (1 mark)
• accept temperature readings and award 1 mark If consistency given either aswhole numbers a to 1 decimal place otherwise penalize fully
• Reflect and ward 0 mark if decimal place has other values other than a ‘0’ or ‘5’ g. 20.2, 18.9

 

• Accuracy

Compare the S.V. to the candidates temperature reading at 2 min and award 1 mark if the reading is within +2.0⁰C of the S.V. otherwise award zero mark

Note

S.V refers to the teacher’s temperature readings at t = 0 min where all the five initial temperature reading are the same or the temperature reading at t=2 minutes in case the 5 initial temperature readings are not the same

 

• Trends (1 mark)

 

Award two halves as follows

• If temperature reading from 0 to 2 min are constant award ½ mark or at least from E-1
• Award ½ mark if temperature readings from t=3 min to t=5 min shows a rise after the initial drop without another drop

 

Note

• The reaction is endothermic a hence temperature must drop if not penalize ½ (in 3 minutes) on trend. i.e. to award the 2^nd ½ mark for the trend there must have been a drop in temperature after 2 ½ minutes
• Reject trend in the 2^nd part of the table the addition of solid A to the acid otherwise accept a minimum of two readings if they are lower and show a rise

–           Show the tick accuracy on the table

 

 

GRAPH

Award a total of 3 marks distributed as follows

• Labeling of axes ……………………………… ½ mark

award ½ mark only if both axes are correct labeled (i.e. temperature on vertical and time on horizontal )

 

Penalties

• Penalise fully for inverted axes
• Penalise fully if wrong units are used otherwise ignore if units are omitted

/not used

• Penalise fully if one axis is correctly labeled

 

• Scale………………… ½ mark

Conditions

• Area covered by plots should be at least half the provided on both axes e. at least 5 big squares on vertical and 4 ½ big squares on horizontal
• Scale intervals must be consistent
• Scale chosen must be able to accommodate all points or plots whether plotted or not check range of readings on the

 

Note

Penalise fully if any of the above conditions are not met

 

 

• Plotting……………………………………………… 1 mark

i).         If 10 or 9 points are correctly plotted award 1 mark ii).  If 8 or 7 points correctly plotted award ½

iii).       If less than 7 points are correctly plotted award 0 marks

 

2. If scale interval changes mark plots (if any ) within the first scale interval and treat to rest of the plots even if the axes are inverted or interchanged and award accordingly

 

 

• The lines and extrapolation…………………………….. (1 mark)
  • Award ½ mark if the plots are joined by two straight lines, accept the lines of best fit
  • Award another ½ marks if for extrapolation where each of the two lines is extended to the 2 ½ minutes mark
  • Accept lines and extrapolation even if the axes are inverted

 

 

 

 

 

99

 

Temperature (^OC)

Chemistry Practical Study Pack

∆T

1989 – 2016

 

 

Temp (^OC)

Temperatur e ( C)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Temp (^OC)

Temp (^OC)

 

 

 

 

 

 

 

Time (minutes)

 

 

 

 

 

 

Temperature (^OC)

Temp (^OC)

 

 

 

 

 

 

 

 

 

 

Time (minutes)

Time (minutes)

 

 

Table 1

Time (min)	0	½	1	1 ½	2	2 ½	3	3 ½	4	4 ½	5
Temp (0C)	18. 0	18.0	18.0	18.0	18.0	X	13.0	13.0	13.5	13.5	14.0

 

• ∆T = Correct reading 6⁰C 1 mark

 

Conditions

• Accept the correct value of ∆T from an extrapolated correct graph with or without showing on the graph for 1 mark
• award ½ mark for correct showing on an extrapolated correct graph if reading for ∆T is wrong or missing
• Ignore sign for ∆T
• Penalise ½ mark for wrong units used otherwise ignore if no units are used/shown
• Reject readings/showing from a wrong graph and award 0 mark for ∆T reject ∆T if coming from the table or wrong graph but accept in (iii) below if used correctly
• Reject ∆T if from the table or wrong graph but accept if it is used correctly otherwise penalize fully if ∆T is strange

 

• ∆H = MC∆T √(expression)

= 20 x 4.2 x Answer (ii) above(6)

= 504 joules

 

Or

∆H = MC∆T

= 20 x 4.2 x Answers (ii) above

1000

= Correct Answer

 

Table 2

	I	II	III
Final burette reading	16.50	32.20	32.20
Initial burette reading	0.00	16.00	16.00
Titre (cm3)	16.50	16.20	16.20

Award a total of 5 marks distributed as follows (i)            Average Titre = 16. 20 + 16.20 = 16 .20cm³

2

• The number of moles of:
  • Moles of NaOH used = 1 x Titre

1000

 

• Moles of NaOH: HCl = 1 :1

Moles    of HCl = Ans I above Or Moles of HCl in 25cm³ of soln = Ans I above.

 

• Ans II x 250 = correct answer

25

Or

Ans II x 10        = Correct Ans

 

Conditions

i).         Penalise ½ mark for wrong transfer of answer (II) ii). Penalise fully for strange figure

iii).        Answer as expected otherwise penalize ½ mark (don’t work at accuracy,  d.p) for wrong answer

 

Notes

• Award fully if correct answer given is based on statement implying multiplication of ten

 

IV).       2 x 20

 

1000                =           0.04

Answer as expected otherwise penalize ½ mark

1. V) Moles of HCl reacted with solid A = Ans IV – Ans III

= Correct Ans

 

 

Conditions

Answer (IV) III must be transferred intact otherwise penalize ½ mark for wrong transfer of either of item or both. However for strange figures penalize fully.

Note

1. If soluble or dissolve is not given but blue ppt mentioned accept and award 1 mark for blue solution
2. If ppt and dissolve are not mentioned but a candidate mentions deep blue solution in excess credit ½ mark and reject the

 

• Ans (iii) Procedure A = Correct ans

ANS v                           UNITS j Mol- OR Kj Mot Or

Ans v = Ans iii procedure A

: I Mole of HCl = Ans (iii) Procedure A

Ans V

=Correct Ans JMol^-1

Or

Ans v = Ans (i) Procedure A (Joules)

; 1 Mole of HCl = Ans (iii) Procedure A

Ans V x 1000

Jmol^-1 or KJ mol^-1

 

2	Observations	Inferences
a	Green solid turns black/ Green solid forms black solid/ residue ; Colourless liquid forms on the cooler part of the test tube/ Colourless vapour condenses on the cooler part of the test tube ; Blue litmus turns red; Red litmus remains red/ the same colour. Penalise fully for contradiction on colour properties Rej. Colourless liquid condenses / colourless vapour forms/moisture condenses/No effect on red litmus/Red litmus remains the same colour	–   Hydrated salt/compound or contain water of crystallization (Tied to colourless vapour condensing) Acidic gas produced (Tied to blue litmus turning red.
b	Black solid / residue reacts dissolves to form green solution Or Green solution formed Ignore – No effervescence Rej. Blue solution/ No change/ reaction	Black solid/ residue is basic/ Colored ion present / or  Cu2+, Fe2+ ions present
c (i)	Blue ppt/ suspension /solid formed / Blue ppt dissolves in excess aqueous ammonia to form a deep blue solution	Cu2+ Present ( tied to blue ppt and deep blue solution Must
(ii)	Effervescence occurs / bubbles formed/ Fizzing; Rej hissing/ Brown/ reddish brown solid deposited/ Green solution turns colourless / Test tube becomes warm /hot	E is a metal above copper in the ECS / Metal E displaces copper/ metal E is more reactive than cooper / metal E reduced Cu2+ ions to Cu ( Tied to brown solid deposit)

 

 

 

3	Observations					Inferences
a	Burns with a yellow sooty smoky flame ½ mark Burns with a luminous sooty/smoky flame					– long chain/ unsaturated organic/ hydrocarbon with a high C: H ratio C = C or – C = C ½ marks Reject C = C, C = C Carbon to carbon double or triple bond in words Alkaline /alkaline
b	Dissolves/ soluble to form a colourless solution					Polar organic compound Note Accept soluble /substance/salt/compound present
c (i)	Effervesnce formed	occurs	or	bubbles	are	R – COOH / H+/ H3O+ Accept – Acidic compound /solution Organic compound ; Carboxylic acid
(ii)	Orange colour K2Cr2O7 solution persists / remain the same / orange / orange colour Rej – Yellow used in place of orange K2Cr2O7 not decolourised					R – OH absent Note : Penalise fully if any other functional groups are mentioned
(iii)	Purple KMnO4 soln is decolorized or KMnO4 soln changes from purple to colourless Note : Rej Solution remains / becomes / turns colourless					– C=C- / C = C – present Accept for unsaturated organic compound present

 

 

NOVEMBER 2009 MARK SCHEME

 

1.

	I	II	III
Final burette reading	22.20	21.50	22.50
Initial burette reading	0.00	0.00	1.00
Volume of solution C used (cm3)	22.20	21.50	21.50

(4 marks)

• i). Average volume of solution C used

= 21.50 + 21.50

2

= 21.50                                                                         (1 mark)

• Moles of sodium hydroxide in the average volume of solution C

100cm³ of sodium contains 0.3 moles of NaOH 21.50cm³ of solution contains 0.3 x 21.5

1000

=          0.00645 moles   (1 mark) iii).                              Moles of hydrochloric acid in 25.0cm³ of solution D

= 0.00645 moles                                                                       (1 mark)

iv).        Morality of hydrochloric acid in solution D.

25cm³ of solution contains        0.00645 moles Hcl

0.00645 x 1000

100cm³ of solution contains                                   25

 

= 0.25M                                                (1mark)

I II III   Final burette reading 21.50 20.90 20.90 Initial burette reading 0.00 0.00 0.00 Volume of solution D used (cm3) 21.50 20.90 20.90

Table 2

 

 

 

 

 

 

• i). Average volume of solution D used

20.90 + 20.90

 

 

 

(4 marks)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2. a).

2                      = 20.90cm³                                (1 mark)

 

ii).        Moles of hydrochloric acid in average volume of solution D used 1000cm³ of solution contains 0.258 moles of HCl

20.90cm³ of solution contains    0.258 x 20.90 moles

1000

= 0.0054 moles             (1 mark) iii).                                                                                   Moles of the metal carbonate, solid A in 25.0cm³ of solution  A.

Mole ratio of acid to carbonate 2: 1                                   (1 mark)

½ x 0.0054

= 0.0027 moles                                                             (1 mark)

iv).       The solubility of the metal carbonate in g/100g of solution mass of carbonate = 0.0027 x 74

in 25.0cm³ of solution = 0.1998g

100g of solution will contain         0.1998 x 100g of carbonate

25

= 0.7992g/100g of solution                               (1 mark)

 

 

Observations                                                   Inferences

Colourless liquid                                                 hydrated salt/ compound or contains Condenses on the cooler parts of test tube                        water of crystallization (Tied to

Gas produced forms white                                Colourless liquid forming after fumes with fumes HCl. (2 marks) Or                 condensation

4

solid sublimes/forms a white sublimate          Ammonia gas (NH ⁺ ) present ( tied to white solid formed on the cooler parts                gas forming with HCl

of the test tube

 

 

 

b).

 

 

 

 

for each

 

 

 

 

 

Pb²⁺ in

ii).

Observations                                       Inferences

No white ppt / No white solid                   Pb²⁺ absent

No white suspension                             No effervescence/ No bubbles

or Al³⁺ present tied to white ppt                 Note: if a candidate mentions

 

Rej. No observable change                    Place of Al³⁺ present credit ½

3

No ppt / change/reaction                         CO ^2- and SO3 absent    Tied to no

No white substance                              Effervescence. (2 marks)

Colourless soln formed                          NB. To award ‘Al³⁺ present it must have

Soln remains colourless                         been credited in b (i) ; To award

No colour change                                   Pb²⁺ absent it must have been mentioned as present in b (i); Ignore mention of Ag⁺ absent

 

 

 

 

iii).

 

Observations

White ppt /solid/suspension

 

Inferences

4

– SO ^2- present

 

 

without

which does not dissolve on boiling         – If a candidate mentions Cl^–

 

4

giving SO ^2- present award ½ mark

Penalise fully for any contradictory ion

 

(1 mark)

Formulae of the ion must be given correctly in all the above inferences. Rej ions given in words only                          (2 marks)

 

 

 

3. a). Observations                                                  Inferences

White solid dissolves to                                     F is a non polar compound

form a colourless solution   (1 mark)                                                                                                                 (1 mark)

Accept a colorless solution formed Without mention of dissolve or soluble For 1 mark

Forms a solution / clear solution without Mention of dissolve or soluble for 1 mk

 

1. Observations Inferences

P^H = 7                                                   Neutral solution

(1 mark)                                              (1 mark)

Note: Ignore mention of colour                  Accpt: Soln neither acidic nor alkaline of mixture; Reject pH range                                                            Rej basic used in place of alkaline

 

 

 

ii).

 

Observations

 

Inferences

 

No effervescence/ No bubbles (1 mark)

H⁺ absent

Accept soln not acidic for ½ mk in the absence of H⁺ absent

Ignore R – COOH absent

 

b).

• Observations Effervescence giving off a Colourless solution formed

Accept Fizzing used in place of Effervescence or bubbles for

(1 mark)

 

1. Observations

Does not turn green. Orange Color of K2 Cr2 O7 (1 mark) Note both initial colour and Final colour must be given Otherwise penalize fully Accpt: Orange colour of K2Cr2O7 solution persists / remains;

Rej: Yellow used in place of orange

Inferences

Carboxylic/alkanoic acid preset Or – COOH present/ H⁺/ H3O⁺

(1 mark) Inferences

Alcohol absent / R – OH Rej – OH (2 marks)

 

 

 

iii).

Observations                                               Inferences

 

Bromine water not decolourised Accept yellow/ Orange / red colour of bromine water persists

 

/ remains                     (1 mark)

C = C /   – C = C – absent

Accept unsaturated organic compound absent for ½ mk. Penalise fully for any contradictory / functional groups

(1 mark)

 

 

 

 

NOVEMBER 2010 MARKSCHEME

 

Q1.       Table 1……………………….                                                                             5 marks

a).        Complete table ………………….                                                                     1 mark

 

NOTE; i).          In case there was wrong arithmetic /substration in the table, use the correct values in averaging for the final answer.

• Where there are two possible average titles use the value which gives the candidates maximum
• If wrong  values  are  averaged,  pick  the  correct  values  (if  any)  following  the principles of averaging, average and award accordingly.

e.g. 1 S.V = 15.80cm³

Conditions values are 15.4cm³, 15,6cm³, 15.8cm³

 

Candidates working

Either               15.4 + 15.6 + 15.8

3

= 15.60cm³                                                       (1 mark)

OR                    15.4 + 15.6

2

= 15.5cm³                                                       (1 mark)

Examiner to pick             = 15.6 + 15.8                 = 15.7cm³

2                                                          (1 mark)

 

2 S.V                 = 15.50cm³

Candidates values are 15.8, 15.6, 15.6 Candidates working

 

 

3 S.V = 15.90cm³

15.6 + 15.6

2                           = 15.6cm³                     ½ mark

 

 

Candidate’s values are 16.0, 15.8, and 15.6 Candidates working

15.8 + 15.6

2                            = 15.70cm³

And award 1 mark instead of ½ mark if the candidates value are used

 

CT – 1; D    – 1; A – 1; PA – 1; FA – 1

 

 

CALCULATIONS

i).         No. of moles of NaOH in 25cm³ of solution B   =    2 x 25

1000

Moles of NaOH in 250cm³ of solution D     = 2 x 25

1000

Hence Conc. of solution D = 2 x 25 x 1000

1000      250

= 0.200 mols

Or

Conc of solution D = 2 x 25 x 1000

1000      250

= 0.200 mol L

Or

Mc Vc = Md Vd = M1 V1 = M2 V2 /Mg Vg = Md Vd Md (Or M2) or md = 2 x 25

100

Or

Conc of solution D = 2 x 1

10

= 0.200 mol-1

 

• Moles of NaOH in 25cm³ of solution D used

= Ans (II) x 25

1000

 

Moles of alkanoic acid used = ¹/3 x ans (II) x 25

1000

Hence conc of solution C = ¹/3 x ans (II) x 25 x 1000

1000              Titre

= correct ans.

OR

Conc of solution C = ¹/3 x ans (II) x 25

Titre

= Correct ans.

OR

Ma Va = ¹/3 = Ma = ¹/3 x ans (II) x 25 MbVb                                    Titre

= correct answer

• Molar mass of the alkanoic acid

 

= 25.0

Ans (III)

= Correct answer

 

Note:    i).         Penalise ½ mark for wrong transfer of ans (III) otherwise penalize fully for strange figures used.

• Penalise ½ mark for wrong answer if arithmetic error is outside +5 units in the 1^st p
• Penalise ½ mark for either omission of the (g) units or for wrong units used

 

 

Procedure

 

 

GRAPH

Table II…………………….. 6 marks

 

• Labelling of axes ………………………………………. ½ mark to award the ½ mark both axes must by correctly labelled

 

Conditions

• Penalise fully for wrong units used otherwise accept correct labeling even if no units are shown
• Penalise fully if only one axis is correctly labelled
• Change in temperature (∆T) must appear on the vertical axis and volume of solution A on horizontal axis, otherwise penalize fully for inverted Axes
• Reject labeling of axes if temperature alone is used instead of change in temperature (∆T) in vertical

 

b).        Scale ……………………………………………………                                ½ mark

• Area covered by the actual plots must be at least 3 ½ big square (vertical axis) by 4 ½ big square (horizontal axis)
• The scale internal must be constant on each axis
• Scale chosen must be able to accommodate the plots, whether plotted or not (chalk the range of values on both axes)

NB:       i).         Penalise fully if any of the above conditions is not met

ii).        Award for the scale even if the axes are in interchanged so long as the above conditions are met

 

c).        Plotting ………………………………………………..            ½ mark i).            For 5 or 6 points plotted correctly award 1 mark

ii).        If 4 or 3 points are correctly plotted award ½ mark iii).           For less than 3 points correctly plotted award 1 mark

• If the scale interval changes, make the plots (if any) in the first scale interval only.

Consider the rest of the plots (If any) as wrong plots

• Accept the correct plots even if the axis are inverted /interchanged

 

 

 

• The line/shape…………………………………….. 1 mark Conditions
  • Award ½ mark for straight line showing a risk
  • Award another ½ mark for an extrapolated line showing a drop NB: Accept lines of best fit
  • If the axes, are interchanged /inverted reject the lines and the readings from the graph in (b) but accept the reading in subsequent workings in (c) and (d)

 

 

108    Chemistry Practical Study Pack                 1989 – 2016

Award 1 mark

 

∆T

 

 

 

 

 

 

 

 

 

 

 

• Accept any one of the following for ½ mark

 

 

 

 

 

∆T                                                   ∆T

 

 

 

 

Volume of solution A (cm³)                          Volume of solution A (cm³)

 

Award 1 mark

 

∆T                                                   ∆T

 

 

 

 

3

Volume of solution A (cm³) b). Volume of solution A= Vcm

NB:

Volume of solution A (cm³)

 

• Accept correct reading of V with or within showing on extrapolated graph for

 

1 mark

• If shown on the graph correctly but reading is wrong or not given award only ½ mark for correct showing on the graph
• Penalise ½ mark for wrong units otherwise ignore if units not given iv). If value of V > 25cm³ reject and award

vi).       Reject showing and reading of V from a wrong graph but accept in (c) below if need correct

 

• Volume of B = 30 – Ans (b) above (30 –v)

correct ans.

 

NB;       i).         V of 30cm³ is unrealistic and unacceptable and hence penalize fully and consequently. Reject working in both d (i) and d (ii) below and award o mark in each case

 

ii).        Penalise ½ mark for wrong units and another ½ mark if working not shown

• i). Ratio of volume A and B

= Ans (b); Ans (c) Or

Ans (c); Ans (b)

= 1: 1

 

NB:       If ratio is not 1: 1 penalise ½ mark but accept the ratio in d (ii) if used correctly

Moles of acid used = Moles of NaOH Molarity of acid = 2 x Ans (c ) x 1000

1000               Ans (b)

= corr. Ans

OR

Conc of solution A = 2 x Ans (c)

Ans b

= Correct Ans

OR

MA VA = MB VB

MA        = 2 x Ans

Ans(b)

= Corr. Ans

 

 

Conditions

• Accept answer tied correct arithmetic otherwise penalise ½ mark for arithmetic error outside +2 marks in the 1^st p
• Penalise ½ mark for wrong transfer of ans in (c) or (b) in both otherwise penalise fully for strange figure in either

 

NB:       Penalise fully for any calculation noted beyond the expected ans.

 

 

 

 

 

 

 

2	Observation	Inferences
a (i)	White ppt	B2+Ca2+, Ba2+, If all the 3 given 2 marks If only 2 given – 1 mark If only 1 given – ½ mark Note: for any contradictory mark out of 1 ½ ,penalize ½ mark for any contradictory
ii)	White ppt which dissolves in excess. reject residue Suspension Accept white solid	Pb2+, NB: Credit Pb2+ only if mention in (i) above, penalize fully for any contradiction
iii)	White PPt	–F contains SO 2–, Cl–, SO 2–, Cl–, or SO 2–, Cl–, 4                     3                          4 SO 2-, CO 2-, 4 ions given – 1 mark 3             3 3 or 2 ions given – ½ mark ions given – 0 mark Penalties

 

		Penalise fully if candidate E contains the above ions – penalize ½ mark for contradictory ions
iv)	Yellow PPt	Pb2+ Penalise fully for any contradictory ions
bi)	Burns with a smoky/sooty flame/sooty flame Accept – yellow sooty	– C=C- / -C=C- Accept ; long chain hydrocarbon, carbon; hydrogen ratio Penalise fully for any contradictory functional group.
(ii) I	I pH is 1 or 3 accept red for ½ mk but reject inference given but reject     inference            given         on        its strength Reject PH range, penalize Fully for colour and correct PH NB: If a wrong colour	strongly acidic Reject – acidic given alone G – is a strong acid ignore – carboxylic acid
II	KMnO4 decolourised Or KMnO4 turns from Purple to colourless Reject KMnO4 turns colourless Solution turns colourless Solution decolourised Solution discolurised	– C = C- or – C = C- R – OH ½ Reject the groups in words – OH Penalise ½ mk for each contractor functional group
iii	Effervescence /bubbles /fizzing odourless gas odourless to differentiate between SO2 & CO2 Reject ; Hissing Odourless mentioned alone	CO 2- present in F (tied to part (a) (iii) 3 Ignore mention of acid ii). Penalise fully for contradiction iii).The inference is tied to effervescence bubbles and odourless

 

 

 

 

NOVEMBER 2011 MARKSCHEME

 

Conditions (ii)

1. Value 1.60 must be intact otherwise penalize fully
2. Should be at least 3 dec. place
3. Penalise ½ mark for arithmetic error if outside + 2 units in the 3^rd depth

 

1. Units may not be given but if given must be correct penalize ½ mark for errors units used

 

	1	2	3
Final burette reading	29.70	33.40	44.60
Initial burette reading	0.00	4.00	15.30
Volume of solution A used (cm3)	29.70	29.40	29.30

 

ii). Concentration in moles per litre of the dibasic acid in solution A Relative molecular mass of A is 126.

1.60 x 1000                   1.60                                         1.60 x 1000      1.60 x 4

250      = 6.4                 126       = 0.0127                       126    126         126

6.4                               moles in a litre                           = 0.051M

 

126       = 0.05               0.0127 x 1000

250

= 4 x 0.00127

= 0.051

 

• Moles of the dibasic acid used; Answer in (ii) above x litre

1000

 

 

 

2 marks

 

= correct answer                                                                       1 mark

 

• Moles of sodium, hydroxide in 25.0cm³ of solution C Ans in (iii) above x 2

=correct answer

1 mark

• Concentration of sodium hydroxide in moles per litre

Answer (iv) above x 1000                                           Answer (iv) above x 40 25

Correct answer                         Or        Mb = Ans (iv) above x titre x 2 25

Correct answer

Or          Ans (iv) x titre Mb x 25

= Correct answer

 

• Calculate the;
  • Average volume of solution A used;

 

	1st Conical flask	2nd Conical Flask
Final burette reading	21.20	33.60
Initial burette reading	9.70	21.20
Volume of solution A used (cm3)	11.50	11.40

 

 

• Moles of the dibasic acid used: Ans (ii) procedure II x titre (table 2)

1000

=          Correct ans

 

• Moles of sodium hydroxide that reacted with the dibasic acid

=          Ans (ii) above x 2

=          Correct ans

 

 

 

1 mark

 

 

1 mark

 

• Moles of sodium hydroxide that reacted with 0cm³ of salt B in solution B;

=Ans (iv) procedure II = Ans (iii) above

=Correct ans.

2 marks v).          Given that I mole of salt B reacts with 2 moles of sodium hydroxide, calculate the;

25. Number of moles of salt B in 0cm3 of solution B Ans (iv) above

2

Correct ans

1 mark

1. Concentration in moles per litre of salt B in solution B Ans I above x 1000

25

 

Ans I above x 40

= Correct ans

 

• Relative molecular mass of salt B;

=          4.75

Ans in II above

= Correct answer > and > 140 penalise ½ mark for ans

 

2. a).i). Observation                                                      Inferences

 

1 mark

 

4

Gas that turns moist litmus paper                     NH ⁺ present (tied to red litmus Blue given off                 turning blue)

Condenses on the cooler parts of                       Solid D is hydrated /Solid D

The tube to form colourless liquid                          contains water of crystallisation Droplets                           (tied to idea of condensation)

White sublimate formed solid Sublimes to form white sublimate

A gas given off that turns moist blue Litmus paper red

A brown residue /solid formed

NB:       Ignore mention of any other ions present

 

• Observations Inferences

Yellow /brown solution formed                                                          Fe²⁺ oxidized to Fe³⁺ On addition of H2 O2 solution                                                                                                        or

Brown ppt formed which is in soluble                Fe³⁺ formed

In excess NaOH solution NB: ignore                                                                        Accept Fe³⁺ present in Mention of initial colour of solution                                                                        mixture of Fe²⁺ in

unless It contradictory                                     solution

NB: Reject Fe³⁺ present /solid or solution D contains Fe³⁺

 

b). i).    Observations                                       Inferences

4

3

3

A white ppt formed                                  SO ^2-, SO ^2- CO ^2- present

NB: Penalise ½ mark for each contradictory ions for a max of ( 1 ½ mark)

 

ii). To the mixture obtained in (i) above, add about 5 cm³ of 2M nitric acid (V) acid Observations             Inferences

3

Effervesces occurs /bubbles of             SO ^2- presents

Gas seen

The white ppt dissolves disappears                   NB: credit only if correctly inferred Correct inference tied to either observation or both

4

Penalise ½ mark for each contrition to a max of 1 mark Ignore SO ² mentioned as absent

• To portion two of solution E in a test–tube, add 2 drops of acidified potassium dichromate

(VI) and warm the mixture

 

Observations                                       Inferences

3

Acidified K2Cr2O7 solution                                  SO ^2- presents

Changes from orange to green                           NB: credit only if correctly inferred Correct inference tied to either observation or both

4

Penalise ½ mark for each contrition to a max of 1 mark Ignore SO ² mentioned as absent

 

3          a).        Observations                                       inferences

 

Burns with a blue flame               Reject C = C / C     C absent

Saturated organic compound/organic Compound with low C: H ratio

Absence of unsaturated organic compound Ignore R-OH if mentioned

 

• Observations Inferences

No of effervescence /No bubbles          Absence of H⁺ or liquid is not acidic

/No of fizzing

Ignore does not dissolved                      Absence of R- COOH

No reaction                                                            Ignore H3O⁺ if mentioned Reject: No hissing on it’s own

 

• Observations Inferences K2Cr2O7 changes from orange to                                            R – OH

green/solution changes from orange     Reject; 1 – alcohol written in to green                  words 2-OH

 

Reject: soln turns green, NB: Penalise fully for any contradicting functional groups

 

 

 

 

 

 

 

 

 

NOVEMBER 2012 MARKSCHEME

 

1. Question I – Procedure
   • i). Moles of Sodium thiosulphate (Solution B) 05 x Average titre

1000

=   Correct answer Conditions

 

• i). Moles of solution A in 0cm³

Moles ratio       moles of A        :            Moles of Na2S2O3 . 5H2O 1 :                6

Moles of A = 1

Moles  of  Na2SO3  SH2O Moles of A = ans a (ii) moles

6            = Correct answer ii).            Concentration of A in moles per litre

25cm³ of A contains ans b(i) above 1000 cm³ of A contains

Ans b(i) x 1000

25

=           correct answer OR

Ans b(i) x 40

=          Correct answer

 

OR           MA VA = 1 MB VB                   6

MA = 0.05 x Average titre

6 x 25

=          Correct answer

 

OR

Answer (b) (i) x 1000 = Correct answer

25

 

Conditions

• Penalise ½ mark fro wrong transfer of ans b(ii) or average titre otherwise penalise fully for strange figure
• Answer must be given to at least 3 p unless it works out exactly to less than 3

d.p otherwise penalise ½ mark

• Penalise ½ mark for answer if arithmetic error is outside +2 units in the 3^rdp d). Units may not be given but if given must be correct otherwise penalise ½ mark

for wrong units used

e).        When formula is wrongly given in the formula method penalise fully NB: Penalise ½ mark for the answers in calculation a (i) and b (ii) if

candidate work beyond the expected answer

 

 

 

 

PROCEDURE II

Table 2 – 6 marks Distribution of marks

Complete table ………………………………………….                                     (3 marks)

 

1. ACCURACY

Compare the candidates 1^st time reading to the S.V if within +2s award 1mk otherwise penalise fully

Note:

• The V is the teacher first time reading
• Put a tick (√ ) on the candidate value if right

 

1. TREND (Tied to the time row)

Award (1 mark) for time reading increasing continuously otherwise penalise fully

 

Graph

1. Labelling Conditions
   • Accept labeling even if no units are shown, otherwise penalise fully if wrong units are shown
   • Penalise fully for inverted axis
   • Penalise fully if only one axis is correctly labeled

 

1. Scale

• Area covered by the actual plots (including the origin) must be at least 4 x 4 large squares ( ½ the grid) otherwise penalise fully
• The scale internal must be consistent on each axis iii). The scale chosen must accommodate all the plots Note:

 

	Penalise fully if any of the above is not met Award for the scale even if the axis are inverted
C.	Plotting Conditions If 5 or 6 points are correctly plotted ……………….	(1 mark)
	If 3 or 4 points are correctly plotted ………… If less than 3 points ……………………………	(½ mark) (0 marks)

 

1. Line

Accept a straight line passing through at least 2 points correctly plotted and through the origin on extrapolation otherwise penalise fully

 

Calculations

i).         For correct showing of ⁱ/t on the graph ½ mark ii).   For stating the correct reading

e.g R = 0.003

iii).       For t = 1/correct value

v).        Correct value ½ (Must have units)

 

 

 

 

Conditions

• Accept correct readings without showing
• Award ½ mark for showing on the graph and 1 If applied correctly in the expression and ½ mark for the answer
• Answer must be at at least 1 p or whole no (if it works out) otherwise penalise
• Allow showing of reading for the candidates graph irrespective of the line as long as the scale is correct(Intervals)
• Award where not shown not stated but correct reading if done for him/her (do it)

 

Penalise

Penalise ½ mark for W.A if the answer is not within +2 units in the 1^st d.p Correct units must be shown otherwise penalise ½ mark

 

2.	a).i).	I).	Observations A white precipitate	Inferences Presence of Pb2+, Ba2+, Ca2+ Only 2 – ½ mark Penalise ½ mark for each contradictory ion
		II).	Observations No white ppt	Inferences Presence of  Ba2+, Ca2+ Pb2+ absent ½ where the above Not mentioned penalise ½ mark for each contradictory ions
		III).	Observations No white precipitate	Inferences Cl- absent Penalise fully for any contradictory ion Ignore mention of S0 2-, SO 2 of CO 2- as absent 4            3                  3

ii).        Observations

Effervescence/bubbled                        Solid contain NO3

Colourless gas/pungent choking           (Tied to red litmus turning blue)

 

Smell

Red Litmus – blue Blue – remains blue

 

3. a). Observations                                       Inferences

No effervescence/no bubbles                                                         Solid F is not acidic No fizzing                                                                               OR

Absence of H+/H30+

• i). Observations                                       Inferences

Burns with a sooty flame                       Unsaturated /long chain /high C-H organic cpd organic cpds ratio present

Smoky flame or luminous                        Flame / Carbon –carbon double/triple Yellow flame            bond written in words or aromatic cpds

 

ii).        Observations                                       Inferences

White suspensions                                                            Compound is slightly soluble Or                                                                                          Or

White solid remains undissolved           Cpd is partially soluble

or

cpd is insoluble/cpd is nonpolar

 

• i). Observations                                                           Inferences Effervescence /Bubbles /fizzing                                                           The mixture is acidic

Or                                                        Or

Accept colorless gas given off               RCOOH or H⁺/H3O present

ii).        Observations                                       Inferences

Bromine water is not decolourised        Carbon – carbon double/triple Or                bond absent

Yellow/orange/brown/red                                    Or

Remains persists                                                            Compound is saturated Bromine water remain yellow

 

NOVEMBER 2013 MARKSCHEME

 

Procedure I. Table 1.

1. Complete table (All readings recorded) ……….
   • Penalise ½ mark once for any space not filled, subject to at least 4 readings beings given otherwise penalize
   • Penalise ½ mark for unrealistic temperature reading either below 10⁰C or more than 40⁰C at t=0
   • Penalise ½ mark for temperature reading, they should all be constant from t=0 to t=7 iv). If two or more rows of temperature readings are given, penalize ½ mark for complete

table based on the rows used to plot the graph. However if the graph is not drawn then mark the first rows of the temperature reading.

v).        If two or more graphs are plotted, mark the complete table based on the first row.

 

1. Use of decimals (tied to at least two readings) accept the temperature reading for ½ mark only if consistently given as either 1 o

i).         Whole number              ii).        1 decimal point of either ‘0’ or ‘5’ Otherwise penalize fully

 

• Accuracy…………………………….

 

hemistr

2016

Compare the candidate temperature reading at t=0 with the school value (S.V) and award ½ mark. If the reading is within +2C of the S.V otherwise penalize fully

Trend …..

 

Awarded as follows;

• ½ mark for continuous rise upto the maximum
• 2^nd ½ mark for temperature being either content at maximum or constant followed by a continuous drop or continuous drop after

Graph……

Distribution as follows.

1. correct labeling of both axes ………………………..

Penalties

• Penalise fully for inverted axes
• Penalise fully for wrong units used other ignore if units are omitted iii). Penalise fully if only one axis labeled

 

1. Scale……………………………………………….

i).         Area covered by plot should be atleast half of grid provided i.e 4 ½ by 3 ii).  Scale interval should be consistent each axis

iii).       All plots/points whether plotted or not (check the range of reading on the note. Penalise fully if any of the above conditions is not met

• Plotting……………………………..

Conditions

• If 8 or 7 correctly plotted ………
• If only 6 to 4 points correctly plotting iii). If less than 4 points correctly plotted …. Note:

• If the scale interval changes mark plots if any within the first scale interval and the first as wrong
• Accept correct plots even if the axes are inverted and award accordingly iii). Mark all plots on the graph to verify the award

 

1. Line/Shape………….

• Accept 2 straight lines intersecting on extrapolation for ……………….
• Accept 2 straight lines not extrapolated whether joined or not for…
• Accept 1^st line of best fit only if it passes through the initial temperature the following are the versions accepted even if the axes are

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Highest change in temperature, OT.

1. i). Accept correct value of OT from correctly extrapolated graph

with/without showing…………. Provided 1^st line passes through the plot at t=0 i.e limited

temperature.

ii).        Award ½ mark for correct showing on a correctly DT value is wrong or missing iii).    Award 0 max for DT stated from a wrong graph

Note:    a).        Ignore +ve or –ve sign on the DT value

b).        Penalise ½ mark for wrong units otherwise ignore if omitted

 

1. Time taken for reaction to be completed

Accept correct time reading from correctly extrapolated with or without showing for …. If wrong units of time are given penalize fully, otherwise ignore omission of units

 

Conditions

• Ignore the formula for working DH, but if given MUST be correct otherwise penalize ½ mark where wrong formula is given
• Penalise ½ mark for wrong units or omission of units on the answer iii). Accept correct transfer of DT even if rejected in a(iii) I above

iv).       Penalise ½ mark for wrong arithmetic on answer if it is outside + 200 joules or + 0.2 KJ iv).        Ignore if no sign is given on the answer otherwise penalize ½ mark for positive sign (+)

 

Procedure II

Table 2 …………………….

1. Complete table ………………………

Conditions

• Complete table with 3 titrations done
• Incomplete table with 2 titrations done ……..
• Incomplete table with only one titration ……………….

 

Penalties

i).         Wrong arithmetric when determining the titre values ii).            Inverted tables

• Burette readings beyond 50ml unless explaining iv). Unrealistic titre values below 1 ml or in hundreds v).       Penalise ½ mark for each to a maximum of ½ mark

 

 

1. TABLE 2 ………………………

Use of decimals …. Tied to 1^st row and 2^nd row only

 

Conditions

• Accept 1 dp or 2 dp used consistently; otherwise penalize fully
• If 2 dpts are used the second decimal value must be ‘O’ or ‘S’ otherwise penalize fully iii). Accept inconstancy in the use of zero’s used as initial burette reading i.e o,0.0 0.00

 

1. Accuracy (Tied to correct titre value …..

Compare the candidate’s titre values with the S.V and award marks as follows i).        If at least one is within +0.1 of S.V award …

ii).        If none is within + 0.1 but at least one is within + 0.2 of S.V award iii).       If no value is within +0.2 award 0 marks

 

Note:

If there is;

• wrong arithmetic or subtraction in the table, then compare the worked

Correct value and award accordingly.

• Where there are two possible S.V’s from the Teacher’s results, indicate both values on the script and use one which is closer to the candidate value to award for accuracy and final answer
• If no S.V is given or can’t be worked out from teacher’s value as per principles of averaging
  • All candidates correct average tutors should be written down and close values picked for averaging per session
  • If candidates average values are too varied ignore them and use KNEC value

 

Compare the candidate’s average titre with S.V i).   If within ⁺0.1 of S.V award

ii).        If not within ⁺ 0.1, but within + 0.2 of S.V award….. ½ mark iii).            If not within + 0.2 of S.V award               0 mark

 

Note;

• If there are 2 possible average titre values use the one that is closer to the V and credit accordingly
• if wrong litre values are averages by candidates, pick correct values (if any) average them and award accordingly

 

4

b).        i).         Moles of MnO ^– = 0.02 x AV. Titre

1000

=Correct Ans.

• Moles of FE²⁺ in 25cm³

Fe²⁺ : Mn04- = 5: 1

= 5 x Ans b(i) above

= Correct Ans.

 

• Moles of iron (i) ions in 250cm³ = Ans b(ii) x 250cm³

25cm³

Or        Ans b(ii) x 10

= Correct Ans

 

1. PRINCIPLES OF AVERAGING Conditions
   • If 3 consistent values averaged …..
   • If 3 titrations done, but only2 are consistent and averaged iii). If only 2 titrations done, are consistent and averaged

• If 3 titrations done, but are inconsistent are averaged……

 

• If 3 titrations done, and all can be averaged but only 2 are averaged vi). If only 2 titrations are done, are inconsistent and averaged ….

 

Penalties

i).         Penalise ½ mark for wrong arithmetic if the error is outside +2 units in the 2^nd d.p ii).     Penalise ½ mark for no working shown but correct answer is written

/stated

• If wrong answer is stated with no working
• If wrong working shown with correct answer however accept

 

Note:

• Accept rounding off/truncation of answer to p e.g 17.666 = 17.67 or 17.66

Otherwise penalize rounding off to 1 dp or to a whole number

• Accept answer if it works out exactly to 1 d.p or to a whole number

 

1. FINAL ACCURACY (Tied to correct average titre)

Penalties/Conditions

• Penalise ½ mark for wrong units used in part b(i)- b(ii) otherwise ignore omission of units
• Penalise ½ mark for wrong transfer in b(i) – b(ii) otherwise penalize fully for strange figure in each case
• Answer in b(i)- b(iii) should be at least unless it works out exactly to less than 4 ps otherwise penalize ½ mark on the answer
• Penalise ½ mark for wrong arithmetic in ans b(i) if the error on the answer is outside 2 units in the 5^th p
• Answer in b(ii) – b(iii) must be as expected, otherwise penalize ½ mark on the answer

 

1. Molar heat of displacement of CU²⁺ ions CU²⁺: Fe = 1:1

= Ans a(iii)

b(iii)

= correct ans.

 

Penalties/conditions

• Penalise ½ mark for wrong transfer of either a(iii) or b(iii) otherwise penalize fully for strange figure
• Penalise 1 mark for arithmetic error outside 200 units of expected answer if the answer is in joules or outside 2 units if answer is in k
• Penalise ½ mark on correct answer if either the correct sign (-ve) or correct unit is missing or both are wrong/missing
• Penalise fully for unrealistic answer e beyond 200 KJ/mole or 200,000 J/Mole

 

Note:

For continued working, mark only the 1^st correct areas.

 

1. Procedure a). i).

 

• I). extrapolated graph

showing/without showing            1 mark II).            from extrapolated graph – wrongly stated but shown on the

graph                                                                           ½ mark

• DH = MCDT

 

= 50 x 4.2 x DT

= Correct answer                   Joules J.j Or = 50 x 4.2 x D.J

1000

= Correct answer (Kilo joules K.J)

-Ignore formula for working DH. Given must be correct otherwise penalize ½ mark for wrong formula.

– Penalise ½ mark for wrong units or omission

-Ignore if no sign is given otherwise if no sign is given otherwise penalize ½ markf or (+) sign

1 ½ mark

2. Procedure

	I	II	III
Final burette reading
Initial burette reading
Volume of solution C used (cm3)

 

 

a).        1 + 11 + 1

3                 = ans

4 marks

 

 

1 mark

 

i).

Observations	Inferences
-Colourless -Odourless gas produced -Gas extinguishes a burning splint -White residue or solid turns yellow when heated and turns white on cooling (1 mark)	-CO3 2- (Extinguishes burning splint) -Zn2+/ZnO formed (turned to white on cooling )     (1 mark)

Award ½ mark upto a maximum of 1 mark

Penalise ½ mark for each contradictory low in each case Reject; ZnO present.

ii).

Observations	Inferences
-Colourless -Odourless gas produced -Gas extinguishes a burning splint -White residue /solid turns yellow when heated and turns white on cooking (1 mark)	-CO3 2- present Penalize fully for any contradictory ion Zn2+ present (1 mark)

 

Reject ; Hissing /Fizzing

iii).

Observations	Inferences
-White ppt -soluble in excess                             (1 mark)	-Zn2+/Zno formed (turned to white ) (1 mark)

 

Penalise fully for contradictory ions

 

 

b).        i).

Observations	Inferences
-White ppt -ignore if ppt is insoluble in excess (1 mark)	–Al3+, Pb2+, Mg2+ present Note (1 mark)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3. a).

 

ii).

 

 

 

 

 

 

 

 

iii).

Penalize fully for ppt dissolves

 

 

Observations	Inferences
– No effervescence -No white ppt   (1 mark)	-CO 2-, SO 2- absent 3             3 (both ½ mark) -Al3+, Mg2+ present (1 mark)

 

Accept : No ppt

½ mark – colourless solution formed

–     Solution remains colourless

 

Observations	Inferences
-White ppt formed -penalise fully if ppt dissolves (1 mark)	-Pb2+ ions absent penalized ½ mark for any contradictory ion SO42- present (1 mark)

 

Penalise fully for any contradictions ions Accept if ions are written in words

 

Observations	Inferences
– melts and burns with a sooty/luminous / yellow smoky flame (1 mark)	-‘C=C’/ C=C- -Organic compound with high C;L -Long chain organic compound – Unsaturated organic (1 mark)

 

 

 

 

 

 

 

 

 

 

b).        i).

Melts on its own for ½ mark Carbon – carbon dissolves C=C/C=C

Alkalines/alkynes

Long chain hydrocarbon

 

Note:

Penalise fully for any contradictory ion

 

Observations	Inferences
-KMNO4/H+ is not decolouress colour of KMN04/H+ remains purple/purple colour of KMNO4/H+ persists or remains the same (1 mark)	-H+/H3O+ or 4 – COOH or carboxyli growing in words/solutions in acidic   1 mark

 

Saturated organic compound present for ½ mark

Observations	Inferences
-Effervescence /bubbles /fizzing (1 mark)	– H+/H3O+ or 4 –COOH or carboxyli growing in words /solution is acidic (1 mark)

Accept : Colourless gas for ½ mark Reject : Hissing/fizzling

c).

Observations	Inferences
-Dip the p H /universal paper into the solution from (b) above -match the colour obtained with the p H chart and not the p H= 1 or 2 (1mark)	-Solution is strongly acidic     (1 mark)

 

Reject: p H range ( p H = 1 -2)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CONFIDENTIAL AND PREPARATION INSTRUCTIONS TO SCHOOLS

October – November 1989 Instructions to Schools.

 

This is information that enables the Head of the school and the teacher in charge of Chemistry to make adequate preparations for Chemistry Practical Examination.

 

In addition to the fittings and substances ordinarily contained in a chemical laboratory, the following should be provided.

 

Requirements per Candidate

 

Each candidate will require the following:

• About 75cm³ of solution W9
• About 150cm³ of solution W11 (oxallic acid)
• About 1g of solid Y
• About 10cm of metal M (magnesium ribbon)
• 1 pipette of 0cm³
• 3 conical flasks
• 1 burette
• 1 measuring cylinder of 100cm³
• 1 beaker of 250cm³
• Tissue paper
• 1 boiling tube
• 1 thermometer (accuracy 5⁰C)
• 1 ruler
• 1 spatula
• 5 test-tubes
• A sharp blade or pair of scissors
• A small funnel

 

Access to

• 250cm³ of distilled water
• Dilute hydrochloric acid
• Phenolphthalein indicator
• Dilute sodium hydroxide
• Aqueous ammonia

 

Preparations

1. Solution W9 is made by dissolving 90cm³ of concentrated hydrochloric acid in distilled water and making it to one litre of This solution MUST be supplied in a burette placed at a central position where it should be accessible to 5 to 10 candidates.
2. Solution W11 is made by dissolving 30g of solid W11 in distilled water and making it up to one litre of solution.

• Solution W12 is made by dissolving 3.20g of sodium hydroxide pellets in distilled water and making it up to one litre of

1. Metal M should be cleaned with sand-paper the day before the

 

 

October /November 1990. Requirements for Candidates

In addition to the fittings, substances and apparatus ordinarily found in a chemistry laboratory each candidate will require the following;

 

• Between 0g and 1.5g of solid D,

 

• About 250cm³ of solution S1, (Sodium hydroxide)
• About 150cm³ of solution S1,
• About 0g of solid Q
• About 400cm³ of distilled water
• One burette
• One 25cm³ of pipette
• One 10cm³ pipette
• One 100cm³ measuring cylinder
• One filter funnel
• One filter paper
• conical flasks (250cm³)
• One thermometer (0-10⁰C – 0-110⁰C)
• One crucible or crucible lid or a metallic spatula
• One spatula
• One test tube holder
• test tubes
• Two boiling tubes
• One dropper

 

Access to:

• Phenolphthalein indicator
• pH paper (range 1-14)
• Solid sodium hydrogen carbonate
• 1% potassium manganate (VII) solution
• 1% bromine water
• Burner
• Concentrated sulphuric acid supplied with a dropper pipette
• About 6cm³ of ethanol

 

Preparations

• Solids D and Q will be provided by the Kenya National Examinations
• Preparations of solution S1:
  • Dissolves 0g of sodium hydroxide in distilled water and make it up to one litre of solution
  • Take 200cm³ of the sodium hydroxide solution prepared in (i) above and dilute with distilled water to make up one litre of solution (SI)
• Preparation of solution S2:

1. I) Dissolve 56cm³ of concentrated sulphuric acid in about 500cm³ of distilled

II).   Take 10cm³ of the sulphuric acid solution prepared in (i) above and dilute it by adding distilled water to make it up to one litre of solution (S2).

 

 

 

October / November 1992 Requirements for Candidates

In addition to fittings and apparatus found in a chemistry laboratory, each candidate will require:

• 60cm³ of solution C2,
• 100cm³ of solution C3
• 150cm³ of solution C5
• 150cm³ of solution C6
• About 1g of solid C7

 

• One, 50cm³ burette
• One, 100cm³ beaker
• One, 25cm³ (or 20cm³ ) pipette,
• One, 10cm³ measuring cylinder
• Three, 250cm³ conical flasks
• Seven, clean dry test–tubes placed in a rack
• One, stop watch / stop clock,
• One, boiling tube
• One,

 

Access to:

• Methyl orange indicator solution,
• 5M lead nitrate solution
• 5M barium chloride solution
• About 10cm³ of solution C4
• Dilute sulphuric acid
• Dilute sodium hydroxide solution,
• Source of heat (Bunsen burner)
• 300cm³ of distilled water
• Note: all the solutions should be freshly prepared and supplied accompanied by

 

Preparations

1. Solution C2 is prepared by dissolving 2g of solid C2 in distilled water and making it up to one litre
2. Solution C3 is prepared by dissolving 0.40g of solid C3 in about 200cm³ of distilled water, adding 20cm³ of 1M sulphuric acid, shaking well and making it up to one litre with distilled water.

• Solution C4 is prepared by placing 0g of solid C4 in 100cm³ beaker, adding 2cm³ of distilled water to make a paste and pouring the paste into 100cm³ of boiling distilled water, boiling the mixture for about one minute and allowing it to cool. Solution C4 is to be prepared on the morning of the examination.

1. Solution C5 is peppered by adding 10cm³ of concentrated hydrochloric acid (specific gravity of 18 or 1.9) in 500cm³ of distilled water and making it up to one litre.
2. Solution C6 is prepared by dissolving 19.2 of solid C6 in about 500cm³ of warm distilled water, cooling the solution, transferring it into a volumetric flask and making it up to one litre with distilled

 

 

 

 

 

 

October /November 1993 Requirements for Candidates

In addition to the equipments, apparatus and chemicals found in an ordinary chemistry laboratory, each candidate will require the following;

• 75cm³ of solution A
• 0cm³ of solid B
• 200cm³ of solution C
• About 1g of solid F

 

• One, 50cm³ burette
• One 25cm³ pipette
• Five 25cm³ conical flasks
• One, 100 cm³ measuring cylinder
• One, filter funnel
• Six, test tubes
• One, spatula
• One boiling tube
• One filter paper cut into small strips of about 1cm and at least 5cm long Access to:
• Phenolphthalein indicator
• About 500cm³ of distilled water
• 05M iodine solution
• 2 M hydrochloric acid solution
• 2M sodium hydroxide solution
• 24M barium dichromate solution
• A wall clock placed in a position visible for all candidates
• Two labels

 

Preparations

• Solution A is prepared by dissolving 40g of sodium hydroxide pellets in about 500cm³ of distilled water then making it up to one litre of solution
• Solution C is prepared by dissolving 7g of solid C in about 500cm³ of distilled water and making it up to one litre of solution
• The 0g solid B should be weighed accurately for each candidate and supplied in a dry weighing bottle or test tube or any other small dry container
• 05M iodine solution is prepared by dissolving 20g of potassium iodide crystals in 600cm³ of water then adding 12.7g of iodide crystals dissolving and making it up to one litre solution

 

October / November 1994 Requirements for Candidates.

In addition to fittings and apparatus found in a chemistry laboratory, each candidate will require.

 

• 200cm³ of solution D
• 150cm³ of solution E
• 50cm³ of solution F
• 50cm³ of solution G
• About 5g of solid H
• One, 50cm³ burette
• One, 100cm³ beaker
• One, 10cm³ measuring cylinder
• One 100cm³ measuring cylinder
• One 25cm³ (or 20cm³ ) pipette
• Three, 250cm³ conical flasks
• Eight, clean dry test–tubes.
• One thermometer (-10⁰C to 110⁰C
• One metallic spatula
• About 5g of solids –        Sodium chloride
  • Potassium chloride
  • Calcium chloride
• One boiling tube
• Stirring rod
• About 1g of steel wool Access
• Phenolphthalein indicator
• 2M sodium
• 2M aqueous ammonia
• 2M sodium chloride
• Bunsen burner (heat source)
• Distilled water
• Each of the above solutions should be supplied with a

 

Preparations

8. Solution D is prepared by dissolving 0g of sodium hydroxide pellets in distilled water and making it up to one litre.
9. Solution E is prepared by dissolving 19.2g of solid E in distilled water and making it up to one litre.

• Solution F is prepared by dissolving 0g of sodium hydroxide pellets in distilled water and top it up to one litre.

79. Solution G is prepared by dissolving 79.4g of solid G in distilled water and making it up to one litre.

 

 

 

 

 

October /November 1995

 

Requirements for Candidates

 

In addition to the equipment, apparatus and chemicals found in an ordinary chemistry laboratory, each candidate will require the following;

• 2.0g of solid J, weighed accurately
• 1.0g of solid K, weighed accurately
• About 2g of solid L
• About 8g of solid N
• 100cm³ of 0M hydrochloric acid
• One, 50cm³ burette
• One, thermometer
• One, stopwatch/stopclock/watch with a second hand
• One, 100cm³ beaker
• Two pieces of aluminium foil (2cm³ each)
• Six test-tubes
• Two wooden splints
• Three blue and three red litmus papers
• One metallic spatula
• One boiling tube
• One 10cm³ measuring cylinder
• One glass rod

 

Access to:

• About 500cm³ of distilled water
• 0M hydrochloric acid (labeled as dilute)
• 0M sodium hydroxide (labeled as dilute)
• Bunsen burner
• About 50cm³ of 1M lead nitrate solution

 

Preparations

The 2.0M hydrochloric acid should be prepared accurately by adding 175cm³ of concentrated hydrochloric acid to about 700cm³ of distilled water. Shake well and make it up to the one litre

 

October /November 1996 Candidates requirements

In addition to the apparatus and chemicals found in an ordinary Chemistry laboratory, each candidate will require the following:

• 150cm³ of solution A
• 100cm³ of solution B
• 100cm³ of solution C
• One 50cm³ burette
• One 25cm³ pipette
• One thermometer (0⁰C to 100⁰C)
• One filter funnel
• About 5g of solid D
• Six clean dry test-tubes on a test-tube rack
• Two boiling tubes
• One metallic spatula
• Two filter papers
• Wooden splint
• Four red and four blue litmus papers

 

• One teat pipette dropper
• About 5g of solid E
• About half a spatula full of solid sodium hydrogen carbonate
• One conical flask

 

Access to

• Bunsen burner
• About 500cm³ of distilled water
• 20 volume hydrogen peroxide
• 2M sodium hydroxide
• 6M hydrochloric acid
• Concentrated sulphuric acid
• Ethanol

NB:       Each of the above reagents should be supplied with a dropper.

 

Preparations

• Solution A is prepared by dissolving 3.16g of solid A in 400cm³ of 2M sulphuric acid and making it up to one litre of solution with distilled
• Solution B is prepared by dissolving 5g of solid B in 200cm³ of 2M sulphuric acid and making it up to one litre of solution with distilled water. This solution should be prepared in the morning of the examination.
• Solution C is prepared by dissolving 0g of solid C in 600cm³ of distilled water and making it up to one litre of solution with the distilled water

 

 

October / November 1997 Requirements to Candidates.

In addition to the fittings and apparatus found in a chemistry laboratory, each candidate will require. A

• 120cm³ of solution F, sulphuric

• 100cm³ of solution G, 5M sodium hydroxide
• 2g of solid H weighed accurately – mg
• One 50cm³ burette
• One 0cm³ pipette
• One 100cm³ measuring cylinder
• One 100cm³ beaker
• Two conical flasks
• One thermometer 0⁰C – 110⁰C
• One 250cm³ beaker
• One label
• One stopwatch/ stopclock or a watch with seconds hand
• About 5g of solid L
• 6 clean dry test-tubes
• One wooden splint
• One filter funnel
• One spatula
• Two blue and two red litmus papers
• About 5g of solid M
• About 5g of sodium carbonate
• One boiling tube
• One test-tube holder

 

• One filter

 

1. Access
   • Concentrated nitric acid
   • 2M sulphuric acid
   • 2M NaOH
   • Phenolphthalein indicator
   • 2M aqueous ammonia
   • 1% Bromine water
   • Acidified potassium permanganate
   • Distilled water in a wash bottle
   • Bunsen burner

NB/ Each of the solutions in Bottle should be supplied with a dropper.

 

Preparations

27. Solution F is prepared by accurately adding 8cm³ of con. H2SO4 (s.g. 1.84) to about 400cm³ of distilled H2O then making it to one litre of solution.
28. SolutionG is prepared by dissolving 0g of NaOH pellets in 600cm³ of distilled H2O then making it to one litre of solution
29. Acidified potassium permanganate is prepared by dissolving 6g of solid KMnO4 in 400cm³ of 1M H2SO4 acid and making it to one litre of solution.
30. 1%Bromine water is prepared by adding 1cm³ (CARE) of liquid Bromine to 100cm³ of distilled H2O in a fume cupboard and shaking thoroughly

 

 

October / November 1998 Requirements to Candidates.

In addition to the fittings and apparatus found in a chemistry laboratory, each candidate will require.

• 250cm³ of hydrochloric acid, solution M.
• 150cm³ of sodium hydroxide, solution N
• 50g of solid P weighed accurately
• Burette 0 – 50cm³
• Pipette 25cm³

 

Means of labeling.

• 100cm³ measuring cylinder
• 250cm³ beaker
• Two conical flasks
• About 3g of solid L
• Six dry test-tubes
• 2 red and 2 blue litmus papers
• 2 boiling tubes
• One wooden splint
• Filter paper
• Filter funnel
• About 2g of Na2CO3
• about 3g of solid S
• A spatula
• A test-tube

 

Access to:

 

• 10cm³ measuring cylinder
• Distilled water
• Universal indicator solution supplied with a dropper
• pH chart
• 2M hydrochloric acid supplied with a dropper
• 2M aqueous ammonia supplied with a dropper
• Wall clock
• 2M aqueous sodium hydroxide supplied with a dropper
• 2M barium chloride supplied with a dropper
• Bunsen burner
• 1M lead(II) nitrate solution supplied with a dropper
• Screened methyl orange indicator supplied with a

 

Preparations

1. Solution M is prepared by adding 0cm³ (S.G = 1 = 1.18) of concentrated hydrochloric acid into 600cm³ of distilled water contained in a one litre volumetric flask and diluting to one litre of solution.
2. Solution N is prepared by dissolving 80g of sodium hydroxide in 600cm³ of distilled water contained in a one litre volumetric flask and diluting to one litre of solution.
3. Screened methyl orange is prepared by dissolving 10g of solid R in 100cm³ of distilled water and labelled screened methyl orange indicator.

 

 

October / November 1999 Requirements to Candidates.

In addition to the fittings and apparatus found in a chemistry laboratory, each candidate will require the following.

 

• One burette 0 – 50cm³
• One pipette 25cm³
• About 100cm³ of solution E
• About 120cm³ of solution F
• Two conical flasks ) 250cm³
• 8 clean dry test-tubes
• About 4g of solid H (supplied on the morning of examination)
• One boiling tube
• One spatula
• Both blue and red litmus papers
• Stop clock/ watch
• Ruler
• 10cm³ measuring cylinder
• Cutting blade / scissors
• 6cm³ length of magnesium ribbon, labelled solid K
• About 50cm³ of 2.0M hydrochloric acid, labelled solution L
• Means of labeling test-tube holder
• One 100cm³ beaker
• Test-tube

 

Access to:

• Distilled water
• Methyl orange indicator

 

• Bunsen burner
• Concentrated nitric acid supplied with a dropper
• 2M hydrochloric acid supplied with a dropper
• 1M barium chloride solution supplied with a dropper
• 2M sodium hydroxide

 

Preparations

1. Solution E is prepared by accurately measuring 10.0cm³ of concentrated hydrochloric acid (1.18gm/cm³) using a burette and adding it to about 500cm³ of distilled water and diluting to one litre of
2. Solution F is prepared by accurately adding 15.3g of solid F in about 800cm³ of distilled water and diluting to one litre of
3. Solution L is prepared by accurately adding 172cm³ of concentrated hydrochloric acid (1.18g/cm³) to about 500cm³ of distilled water and diluting to one litre of

October / November 2000 Requirements to Candidates

In addition to the fittings and apparatus found in a chemistry laboratory, each candidate will require.

 

• About 90cm³ of solution L
• About 150cm³ of solution M
• One burette 0 – 50cm³
• One pipette 25cm³
• One thermometer 0 – 110⁰C
• Two conical flasks
• One filter funnel
• 3 filter papers
• 10cm³ of solution P contained in a conical flask
• 6 clean dry test-tubes
• 50 or 100cm³ measuring cylinder
• 3 g of solid G
• 100cm³ beaker
• Stop clock / watch
• 30cm³ of 2M sodium hydroxide in a beaker
• One 10cm³ measuring

 

 

 

Access to

• Methyl orange indicator – supplied with dropper
• Phenolphthalein indicator – supplied with dropper
• Distilled water
• 2M sodium hydroxide – supplied with dropper
• 2M aqueous ammonia – supplied with dropper
• 2M nitric acid – supplied with dropper
• 2M hydrochloric acid – supplied with dropper
• 1 M acidified barium chloride – supplied with

 

Preparations

1. Solution L is prepared by dissolving 6g of solid L in 600cm³ of distilled water and diluting to one

 

litre of solution.

2. Solution M is prepared by accurately adding 9cm³ of concentrated hydrochloric acid (density 18g/cm³) to about 500cm³ of distilled water and diluting to one litre of solution.
3. Solution P is prepared by mixing 80g of solid Q and 20g of solid R and dissolving the mixture in about 800cm³ of distilled water then diluting to one litre of

 

October / November 2001 Requirements to Candidates.

In addition to the fittings and apparatus found in a chemistry laboratory, each candidate will require.

• About 20cm³ of solution
• about 100cm³ of solution B
• About 60cm³ of solution C
• About 100cm³ of solution
• One burette
• One pipette
• Two conical flasks (250cm³)
• One filter funnel
• One boiling tube
• One thermometer 0 – 110⁰C
• One 10cm³ measuring cylinder
• 50 or 100cm³ measuring cylinder
• 1g of solid E
• 4 clean dry test-tubes
• One test-tube holder
• 2 blue and 2 red litmus papers
• 0 – 3 g of solid F
• 0 – 2g of solid G
• 100cm³ beaker
• One

 

 

 

 

 

 

Access to.

• Distilled water
• Phenolphthalein indicator
• 2M sodium hydroxide – supplied with a dropper
• 2M sulphuric acid – supplied with a dropper
• 2M lead (II) nitrate – supplied with a dropper
• Bromine water – supplied with a dropper
• Acidified potassium permanganate
• Bunsen

 

Preparations.

1. A is prepared by dissolving 24g of sodium hydroxide pellets in about 800cm³ of distilled water and diluting to one litre of solution
2. B is prepared by adding 12cm³ of hydrochloric acid (specific gravity 18g/cm³) (measured

 

accurately) in about 500cm³ of distilled water and diluting to one litre of solution.

3. C is made by dissolving 6g of solid C in about 900cm³ of distilled water and diluting to one litre of solution.
4. D is prepared by adding 167cm of solution A to 600cm³ of distilled water and diluting to one litre of solution
5. Bromine water is prepared by adding 2ml of liquid bromine to 100cm³ of distilled water and the mixture stirred well in a fume cupboard
6. Acidified potassium permanganate is made by adding 16g of solid potassium permanganate to 400cm³ of 2M sulphuric acid and diluting to one litre of solution using distilled water.

 

October / November 2002 Requirements to Candidates.

In addition to the fittings and apparatus found in a chemistry laboratory, each candidate will require. A

• about 120cm³ of solution A
• about 150cm³ of solution B
• about 40cm³ of solution C supplied with a dropper
• about 40cm³ of solution D supplied with a dropper
• about 150cm³ of distilled water in a wash bottle
• about 2g of solid G
• about 5g of solid H
• 10cm of sodium sulphate solution
• about 15cm³ of solution E supplied with a dropper
• two 200ml or 250ml beaker
• one 10cm³ measuring cylinder
• one burette 0 – 50ml
• one 50ml or 100ml measuring cylinder
• 15cm³ of solution F
• one boiling tube
• one filter funnel
• two pieces of filter paper (whatman 1 size 11.0cm)
• 6 clean dry test-tubes
• one test-tube holder
• one clean metallic spatula
• two labels
• one stopwatch / clock
• Atleast 6cm length of universal indicator paper (full range) pH 1 –

 

1. Access to
   • Bunsen burner (in good working condition).
   • Barium nitrate solution supplied with a dropper
   • 2M sodium hydroxide – supplied with a dropper
   • 2M hydrochloric acid – supplied with a dropper
   • 2M aqueous ammonia – supplied with a dropper
   • pH chart pH 1 – 14
   • bromine water – supplied with a dropper
   • acidified potassium permanganate supplied with a dropper

 

Preparations

1. Solution A is prepared by adding 200cm³ of fresh 20 volume hydrogen peroxide to about 600cm³

 

of distilled water and diluting to one litre of solution. (This solution should be prepared one day before the day of examination, stored in Stoppard container and supplied on the morning of the examination).

2. Solution B is 2M sulphuric acid
3. Solution C is prepared by dissolving 12g of solid C in about 800cm³ of distilled water and diluting to one litre of
4. Solution D is prepared by adding 10g of solid D in about 700cm³ of distilled water and diluting to one litre of
5. Solution E is prepared by dissolving 10g of solid E in about 600cm³ of warm distilled water and diluting with warm water to one litre of
6. Solution F is prepared by dissolving 30g of solid F in about 900cm³ of distilled water and diluting to one litre of

October / November 2003 Requirements to Candidates.

In addition to the fittings and apparatus found in a chemistry laboratory, each candidate will require.

 

A.

• about 80cm³ of solution P
• about 120cm³ of solution Q
• one burette 0 – 50ml
• one pipette 25ml
• two conical flasks 250ml
• 9g of solid S weighed accurately
• 35cm³ of solution T
• one thermometer 0 – 110^oC
• one 100ml beaker
• one 50ml or 100ml measuring cylinder
• about 200ml of distilled water in a wash bottle
• 3g of solid V
• one 10ml measuring cylinder
• one boiling tube
• one spatula
• 6 clean dry test-tubes
• 1ml of 5M barium chloride supplied in a test-tube and labelled 0.5MBaCl2
• 2cm³ of 2M hydrochloric acid supplied in a test-tube and labelled 2MHCl
• About 35cm³ of solution

 

1. Access to
   • 2M sodium hydroxide
   • 1M lead (II) nitrate solution
   • Solution W

These solutions should be supplied with droppers.

 

Preparations

1. Solution P is prepared by dissolving 2g of solid P in 400cm³ of 1M sulphuric acid and diluting to one litre of solution using distilled water.
2. Solution Q is prepared by dissolving 7g of solid Q in 400cm³ of 1M sulphuric acid and diluting to one litre of solution using distilled water. This solution is to be prepared in the morning of the examination and supplied to candidates in containers sealed with aluminum foil. (The solid should be dissolved in the sulphuric acid immediately after weighing).
3. Solution W is prepared by dissolving 5g of solid W in 500cm³ of 1M sulphuric acid and diluting to one litre of solution using distilled

 

4. Solution R is prepared by dissolving exactly 0g of sodium hydroxide pellets in about 800cm³ of distilled water and diluting to one litre of solution and allowed to cool to room temperature.
5. Solution T is prepared by dissolving 63g of solid T in about 900cm³ of distilled water and diluting to one litre of solution and allowed to attain room

 

NB/ The quantities in the above preparations will depend on the number of candidates in a centre.

 

October / November 2004 Requirements to Candidates.

In addition to the fittings and apparatus found in a chemistry laboratory, each candidate will require.

 

A.

• Exactly 3cm³ length of solid
• About 80cm³ of solution B
• About 120cm³ of solution C
• one burette (0 – 50ml)
• one pipette 25ml
• one thermometer (0 – 110⁰) C
• one 100ml beaker
• two 250ml conical flasks
• one stopwatch / clock
• 6 clean dry test-tubes
• one boiling tube
• about 200cm³ of distilled water in a wash
• one label
• about 5cm³ of solution E in a test-tube
• about 5cm³ of solution F in a test tube
• about 5cm³ of solution G in a test tube
• about 6cm³ of solution H in a test tube
• one clean glass rod
• one 10ml measuring cylinder
• 1 ml of chlorine water supplied in a -tube and sealed with aluminium foil
• 2 ml of 1% bromine water supplied in a test-tube and sealed with aluminum

 

1. Access to
   • 2M sodium hydroxide supplied with a dropper
   • phenolphthalein indicator
   • 5M barium chloride supplied with a dropper
   • 05M lead (II) nitrate solution supplied with a dropper
   • Bunsen burner in good working

 

Preparations

1. Solution B is prepared by dissolving 2 cm³ of concentrated hydrochloric acid density 1.18g/cm³ in about 600cm³ of distilled water and diluting to one litre of solution.
2. Solution C is prepared by dissolving 12g of solid sodium hydroxide pellets in about 800cm³ of distilled water and diluting to one litre of
3. Solution E is prepared by dissolving 60g of solid E in about 900cm³ of distilled water and diluting to one litre of
4. Solution F is prepared by dissolving 30g of solid F in about 500cm³ of distilled water and diluting to one litre of
5. Solution G is prepared by dissolving 30g of solid G in about 700cm³ of distilled water and diluting

 

to one litre of solution.

6. Solution H is prepared by dissolving 60g of solid H in about 600cm³ of distilled water and diluting to one litre of
7. Chlorine H2O is prepared by dissolving 250cm³ of 5% chlorine H2) (5% sodium hypochloric) to 750cm³ of distilled H2
8. 1% bromine H2O is prepared by adding 1cm³ of liquid bromine to 100 of distilled H2O and shaking one mixture well to dissolve (This mixture will dissolve ( this should be done in the same chamber)

 

 

October / November 2005 Requirements to Candidates.

In addition to the fittings and apparatus found in a chemistry laboratory, each candidate will require.

 

A.

• About 100cm³ of solution K
• About 75cm³ of solution L
• One burette 0 – 50
• one pipette 25ml
• 5g of solid M accurately weighed and supplied in a clean dry test-tube.
• one tripod stand with a wire gauze
• one 200ml or 250ml beaker
• one Bunsen burner
• one thermometer 0 – 110⁰C
• one stopwatch / clock
• one test-tube holder
• about 5g of solid N
• 5 clean and dry test-tubes
• one boiling tube
• one 10ml measuring cylinder
• about 10cm³ of solution P
• about 5g of solid Q
• about 1g of solid sodium hydrogen
• one blue and one red litmus paper
• 5 pieces of filter paper
• one spatula
• about 150cm³ of distilled water supplied in a wash bottle
• two 100ml beakers
• one filter funnel
• one 100ml measuring cylinder
• a small roll of tissue paper (approximately 25cm³ long)

 

1. Access to
   • 2M aqueous ammonia
   • 5M barium nitrate solution
   • 2M hydrochloric

 

Preparations

1    Solution K is prepared by dissolving 37.32g of sodium hydroxide pellets in about 600cm³ of distilled water and diluting to one litre of solution.

2. Solution L is prepared by dissolving 0g of solid L in about 600cm³ of distilled water and

 

diluting to one litre of solution.

3. Solution P is prepared by dissolving 50g of solid P in about 700cm³ of distilled water and diluting to one litre of

 

October / November 2006 Requirements to Candidates.

In addition to the fittings and apparatus found in a chemistry laboratory, each candidate will require

• 5g of solid A supplied in a boiling tube
• 110cm of solution B
• about 450cm³ of distilled water supplied in a wash bottle
• about 5g of solid E supplied in a dry stoppered container
• about 5g of solid F supplied in a dry stoppered container
• about 10cm³ of aqueous sodium sulphate supplied in
• one burette 0 – 50mls
• one pipette 25ml
• one pipette filler
• one thermometer -10 ^oC – 110 o C
• one 250ml volumetric flask
• two 250mls conical flask
• one Bunsen burner
• one tripped sled and wire gauge
• 5 dry test tubes
• one boiling tube
• 2 filter papers (whatman 1 125mm)
• one filter funnel
• one filter holder
• one metallic spatula
• one 10ml measuring cylinder
• means of labeling
• one clean Access to:
• 2M NaOH supplied with a dropper
• 2M HCl
• Bromine H2O supplied with a dropper
• Phenolphthalein indictor supplied with a dropper
• Wall

 

Preparations

1. Solution B is prepared by dissolving 48g of solution B in about 400cm of 2M sulphuric acid and diluting to one litre of solution with distilled water.
2. Aqueous sodium sulphate is prepared by dissolving 10g of solid Na SO4 Diluting with distilled water to one litre of solution
3. Bromine water is prepared by diluting 1ml of liquid bromine with 100cm³ of distilled water in a fume cupboard
4. Solid A should be weight accurately in a fume clipboard or a well ventilated room.

 

 

October / November 2007 Requirements to Candidates.

 

In addition to the fittings and apparatus found in a chemistry laboratory, each candidate will require.

 

• About 120cm³ of solution
• about 120cm³ of solution B
• About 100cm³ of solution
• one pipette 0ml
• one pipette filler
• one volumetric flask 250ml
• one burette 0 – 50ml
• two conical flasks
• 8 clean dry test-tubes
• test-tube rack
• one thermometer – 10⁰C – 110⁰C
• two boiling tubes
• about 5g of solid E in a stoppered container
• one blue and one red litmus paper
• one 10ml measuring cylinder
• about 500ml of distilled water in a wash bottle
• one test-tube holder
• one PH chart paper range 1 to 14
• about 2cm³ of solution G
• 1g of sodium carbonate (solid)
• one watch glass
• about 5cm³ of solution H
• about 10cm³ of ethanol (absolute) in a Stoppard container labelled liquid F
• spatula
• two clean dropper
• Means of

 

Access to:

• Methyl orange indicator supplied with a dropper
• Bunsen burner
• universal indicator supplied with a dropper
• 2M aqueous ammonia supplied with a dropper
• 5M barium nitrate solution
• 2M nitric acid
• Wall

 

Preparations

1. Solution A is prepared by dissolving 0cm³ of 1.84g/cm (98%) concentrated sulphuric acid in about 600cm³ of distilled water and diluting to one litre of solution.
2. Solution B is prepared by dissolving 0g solid B in about 500cm³ of distilled water and diluting to one litre of solution.
3. Solution C is prepared by dissolving 0g of sodium hydroxide pellets in about 700cm of distilled water and diluting to one litre of solution.
4. Solution G is prepared by dissolving 100g of solid G in about 400cm³ of distilled water and diluting to one litre of
5. Solution H is prepared by dissolving 25g solid H in about 600cm³ of 2M sulphuric acid and diluting to one litre of

 

NB/ The test-tubes provided should have a capacity of at least 15cm³.

 

October / November 2008

 

Requirements to candidates.

In addition to the fittings and apparatus found in a chemistry laboratory, each candidate will require.

• 1g of solid A weighed accurately and supplied in a dry stoppered container
• about 60cm³ of solution B
• about 130cm of sodium hydroxide solution
• one thermometer – 10 ^oC – 110 ^oC
• one stop watch/clock
• one 100ml beaker
• one burette 0 – 50ml
• one pipette 25ml
• one bolometric flask 250ml
• about 500cm³ of distilled water supplied in a wash bottle
• one label or means of labeling
• one pipette filler
• two conical flasks
• about 5g of solid D supplied in a stoppered container
• 2g of solid E supplied in a stoppered container.
• about 5g of solid F supplied in a stoppered container
• six clean dry test-tubes
• one blue and one red litmus paper
• one 10ml measuring cylinder
• one metallic spatula
• about 3g of sodium hydrogen carbonate (solid)
• one test-tube holder
• 15cm³ of 2M hydrochloric

 

Access to.

• Bunsen burner
• 2M aqueous ammonia supplied with a dropper
• acidified potassium dichromate (IV) supplied with a dropper
• acidified potassium manganate (VII) supplied with a dropper
• Phenolphthalein indicator supplied with a

 

Preparations

1. Solution B is prepared by adding 0cm³ (1.18g/cm) of concentrated hydrochloric acid to about 500cm³ of distilled water and diluting to one litre of solution.
2. Acidified potassium dichromate (VI) is prepared by dissolving 25g of solid potassium dichromate

(VI) in about 600cm³ of 2M sulphuric acid and diluting to one litre of solution.

3. Acid KMnO4 16 g in 500cm³ of 2M H2SO4 dilute to 1l.
4. NaOH 0g            700cm³ H2O                    diluting to 1 litre

 

October / November 2009 Requirements to Candidates.

In addition to the fittings and apparatus found in a chemistry laboratory, each candidate will require.

• 8g of solid a weighed accurately and supplied in a stopperd container.
• about 60cm³ of solution G
• one 250ml volumetric flask
• one pipette, 250ml and a pipette filler

 

• one burette 0 – 50ml
• 2 labels
• about 120cm³ of solution C
• three dry conical flasks (250ml)
• one dry filter funnel
• one 250ml dry beaker
• one filter paper whatman 125mm 1
• 5g of solid E supplied in a stoppered container
• six dry test tubes
• one 100ml measuring cylinder
• one 10ml measuring cylinder
• about 500cm³ of distilled water supplied in a wash bottle
• one oiling tube
• one glass rod
• 5g solid F supplied in a stoppered container.
• 5cm³ of absolute ethanol supplied in a stoppered container on the day of
• 2g of solid sodium hydrogen carbonate
• spatula
• one test-tube holder

 

Access to:

• Bromine water supplied with a dropper
• acidified potassium dichromate (VI) supplied with a dropper
• 2M aqueous ammonia supplied with a dropper
• Bunsen burner
• tissue paper
• aqueous lead (II) nitrate supplied with a dropper
• universal indicator solution pH 1 – 14 supplied with a dropper
• pH chart range 1 – 14
• freshly prepared methyl orange indicator supplied with a dropper

 

Preparations

1. Solution B is prepared by dissolving 215cm³ of HCl of density 1.18g/cm³ in abut 500cm³ of distilled water and making to one litre of solution using distilled water and labelled solution B.
2. Solution C is prepared by dissolving 0g of NaOH pellets in about 800cm³ of distilled water and making to one litre of solution using distilled water and labelled solution C.
3. Acidified potassium dichromate (VI) is prepared by dissolving 25g of solid potassium dichromate

(VI) in about 400cm³ of 2M H2SO4 acid and making to one litre of solution using distilled water and labelled acidified potassium dichromate (VI) solution.

4. Bromine water is prepared by adding 1cm of liquid bromine to 100cm³ of distilled water and stirring well in a well in an efficient fume
5. Lead (II) nitrate is prepared by adding 30g of solid lead (II) nitrate in about 700cm³ of distilled water and making up to one litre of solution using distilled water and labelled lead (II) nitrate

 

 

October /November 2010 Candidates Requirements

In addition to the apparatus and fittings found in a chemistry laboratory, each candidate will require the following;

 

• About 150cm³ of solution A labeled solution A
• About 150cm³ of solution B labeled solution B
• About 80cm³ of solution C labeled solution C
• One pipette 0ml
• One pipette filler
• One volumetric flask (250.0ml)
• Four labels
• About 500cm³ of distilled water
• One burette 0ml
• Three conical flasks
• One 10ml measuring cylinder
• One 100ml measuring cylinder
• Two boiling tubes
• One thermometer -10⁰ C to 110⁰C
• About 5 g of solid E supplied in a stopper container
• Six clean dry test-tubes
• About 1g of solid F supplied in a stopper container
• About 5g of solid G supplied in a stopper container
• pH chart 1-14; and universal indicator solution supplied with a dropper
• One 100ml beaker
• One metallic spatula
• One clean dropper

 

Access to

• Phenolphthalein indicator supplied with a dropper
• 2 M sulphuric (VI) acid supplied with a dropper
• 2 M sodium hydroxide supplied with a dropper
• 5M potassium iodide supplied with a dropper
• Bromine water supplied with a dropper
• Acidified potassium manganate (VII) supplied with a dropper

 

• Bunsen burner

 

Preparations

1. Solution A is prepared by taking 190.0cm³ of concentrated hydrochloric acid (Specific gravity 1.18) adding it to 600cm³ of distilled water in a 1 litre volumetric flask and diluting it to the mark. Label this solution as solution

 

2. Solution B is prepared by dissolving 0g of sodium hydroxide pellets in 800cm of distilled water and diluting it to the mark. Label it as solution B.

 

3. Solution C is prepared by dissolving 25g of solid C in 600cm³ of distilled water and diluting it to the Label this as solution C

 

4. Bromine water is prepared by taking 1cm³ of liquid bromine and dissolving it in 100cm³ of distilled water in a fume This must be fleshly prepared and supplied in a dropper battle

 

5. Acidified potassium manganate (VII) is prepared by dissolving 16g of solid potassium manganate (VII) in about 600cm³ of 2M Sulphuric (VI) acid and adding distilled water to make 1 litre.

 

 

October /November 2011

 

In addition to the apparatus and fittings found in a chemistry laboratory, each candidate will require the following;

 

A.

 

1. 60g of solid A weighed accurately and supplied in a stoppered container.
2. About 80cm³ of solution
3. about 200cm³ of solution C
4. One burette 0 – 50ml
5. One pipette 0ml
6. One pipette filler
7. One 250ml volumetric flask
8. Three 250ml conical flasks
9. 4 labels
10. About 5g of solid D in a stoppered container
11. one spatula
12. Six clean dry test – tubes
13. One boiling tube
14. one red and one blue litmus papers
15. 4cm³ of solution E in a test tube and labeled solution
16. about 500cm³ of distilled water in a wash bottle
17. about 10cm³ of liquid F supplied in a stoppered test tube and labeled liquid (Liquid F is absolute ethanol)
18. One clean and dry watch glass
19. 2gm of solid sodium hydrogen carbonate
20. one test – tube holder
21. one stop watch
22. One 10ml measuring cylinder

 

1. ACCESS TO:

 

1. Bunsen burner
2. Phenolphthalein indicator supplied with a dropper
3. 2M sodium hydroxide supplied with a
4. 20V hydrogen peroxide supplied with a dropper October /November 2012

In addition to the apparatus and reagents found in a chemistry laboratory, each candidate will require the following:

 

1. about 150cm³ of solution A
2. about 100cm³ of solution B
3. about 45cm³ of solution C
4. about 50cm³ aqueous potassium iodide
5. about 60cm³ of solution D
6. about 50cm³ of 2M sulphuric (vi) acid
7. one pipette 0ml
8. One pipette filler
9. One burette 0 – 50ml
10. two 250ml conical flasks
11. One 10ml measuring cylinder
12. Six dry test tubes
13. One stop watch or clock
14. Test – tube rack
15. about 5g of solid E supplied in a stoppered container
16. two boiling tubes
17. one red and one blue litmus papers
18. test – tube holder
19. 3 x1 cm piece of aluminium foil
20. about 5 of solid F in a stoppered container
21. about 2g of solid sodium hydrogen carbonate
22. about 20cm³ of 2M hydrochloric acid
23. three 5cm whatman No. 1 filter papers
24. one filter funnel
25. one metallic spatula
26. about 500cm³ of distilled water
27. one 100ml beaker
28. 8 small labels

 

 

 

 

Access to:

 

1. aqueous sodium sulphate supplied with a dropper
2. aqueous sodium chloride supplied with a dropper
3. aqueous barium nitrate supplied with a dropper
4. aqueous lead (II) nitrate supplied with a dropper
5. 2M sodium hydroxide supplied with a dropper
6. Bunsen burner
7. Bromine water supplied with a dropper

 

NB:  Solids A, C, D, E and F will be supplied by the Kenya National Examination Council

 

1. Solution A is prepared by dissolving 20g of solid A in about 600cm³ of distilled water and diluting to one litre of solution. Label this solution as solution A.
2. Solution B is prepared by dissolving 40g of solid sodium thiosulphate (Na2S2O3. 5H2O) in about 800cm³ of distilled water and diluting to one litre of solution. Label this as solution B.
3. Solution C is prepared by dissolving 40g of solid C in about 800cm³ of distilled water and diluting to one litre of solution. Label this as solution C.
4. Potassium iodide is prepared by dissolving 5gm of solid potassium iodide in about 800cm³ of distilled water and diluting to ne litre of Label this as potassium iodide.
5. Solution D is prepared by placing 10g of solid D in 1000cm³ of distilled Heating the mixture to boiling and allowing it to cool to room temperature. Label this as solution D
6. Sodium sulphate solution is made by dissolving 14.2g of solid sodium sulphate in about 800cm³ of distilled water and diluting to one litre of Label this as aqueous sodium sulphate.
7. Sodium chloride solution is made by dissolving 85g of solid sodium chloride in about 800cm³ of distilled water and diluting to one litre of solution. Label this as aqueous sodium chloride.
8. Barium nitrate solution is prepared by dissolving 0gm of solid barium nitrate in about 800cm³ of distilled water and diluting to one litre of solution. Label this as aqueous barium nitrate.
9. Lead (II) nitrate is prepared by dissolving 0gm of solid lead (II) nitrate in about 800cm³ of distilled water and diluting to one litre of solution. Label this as aqueous lead (II) nitrate.
10. Bromine water is prepared by adding 1cm³ of liquid bromine in 100cm³ of distilled water and shaking well in a fume Label this as bromine water.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

October /November 2013

 

In addition to the apparatus and reagents found in a chemistry laboratory, each candidate will require the following:

 

1. about 80cm³ of solution A
2. 60g of solid B weighed accurately and supplied in a stoppered container
3. about 100cm³ of solution C
4. one burette 0 – 0 ml;
5. one 100ml beaker
6. one thermometer – 10⁰ – 110⁰C
7. One stop watch/ clock;
8. one 250ml volumetric flask
9. One 10ml measuring cylinder
10. about 70cm³ of 2M sulphuric acid (VI) acid
11. about 500cm³ of distilled water supplied in a wash bottle

 

12. two labels
13. one 0ml pipette
14. one pipette filler
15. two 250ml  conical flasks;
16. 0g of solid E supplied in a stoppered container
17. two boiling tubes
18. 3 filter papers ( whatman no 1 125mm)
19. One filler funnel
20. six dry test tubes
21. One burning splint
22. 5g of solid G supplied in a stoppered container
23. One metallic spatula
24. 2g of solid sodium hydrogen carbonate supplied in a stoppered
25. Fresh universal indicator
26. pH chart range 1- 14
27. One test tube holder Access to:
28. Bunsen burner
29. 2M hydrochloric acid
30. 2M aqueous ammonia supplied with a dropper
31. 5 barium nitrate supplied with a dropper

 

Preparations

1. Solution A is prepared by dissolving 125.2g of hydrated copper (II) sulphate is about 800cm³ of distilled water and diluting tone litre of solution and labeled solution
2. Solution C is prepared by placing 3.2g of solid C in one litre volumetric flask, adding 100cm³ of 2M sulphuric (VI) acid followed by 700cm³ of distilled water shaking to dissolve then diluting to the Label this as solution C.
3. Solid E is prepared by weighing 0.5 of solid E1 and 0.5 g of zinc carbonate putting both of them in one stoppered container and labeled solid E