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Bureti Joint Evaluation -2012 Question Paper

Bureti Joint Evaluation -2012

Course:Secondary Level

Exam Year:2012

Name………………………………………………………. Index No…………………/…….
School……………………………………………………… Date ………………………….…
Candidate’s Signature………………………

233/1
CHEMISTRY
Paper 1
JULY/ AUGUST 2012
Time: 2 Hours

BURETI DISTRICT JOINT EVALUATION - 2012
Kenya Certificate of Secondary Education (K.C.S.E)

233/1
CHEMISTRY
Paper 1
JULY / AUGUST 2012
Time: 2 Hours

INSTRUCTIONS TO CANDIDATES

- Write your name and index No. in the spaces provided above.
- Sign and write the date of the examination in space provided.
- Answer ALL the questions in the spaces provided.
- Mathematical tables and electronic calculators may be used for calculations
- All working must be clearly shown where necessary

FOR EXAMINER’S USE ONLY
QUESTION MAXIMUM SCORE CANDIDATE’S SCORE
1-29 80

This paper consists of 12 printed pages.
Candidates should check the question paper to ascertain that all pages are Printed as indicated and that no question is missing
1. Name the method of separation that can most suitably be used to separate the following mixtures
a) Gasoline from petroleum. (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
b) Benzoic acid and potassium carbonate. (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
c) Oil from cashew nuts. (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
2. The table below shows information about three solid substances A,B and C.Study it and answer the question that follow.
SOLID A COLD WATER HOT WATER
A Soluble soluble
B Insoluble Insoluble
C Insoluble Soluble

Describe how you will separate the three solids from a mixture of three three. (3mks)
………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………
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3. The diagram below shows the set-up that can be used to prepare and collect oxygen gas. Study it and answer the questions that follow.

a) Identify two mistakes from the diagram which must be corrected for one to collect dry oxygen gas. (2mks)
………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………
b) What property of oxygen gas makes it possible to be collected over water. (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
4. The table below gives information about some reactions of metals A,B, C and D and their rates.

METAL Reaction with acid Reaction with water Action of heat on its nitrate
A Hydrogen evolved No reaction Oxide formed
B NO reaction No reaction Metal formed
C Hydrogen evolved Hydrogen evolved Oxide formed
D NO reaction NO reaction Oxide formed

Arrange the metals in order of decreasing activity (Starting with the most reactive) (2mks)

5. The table below gives information on four elements by letters K,L,M and N.Study it and answer the questions that follow. The letters do not represent the actual symbol of the elements

Element Electron arrangement Atomic radius (nm) Ionic radius(nm)
K 2.8.2 0.136 0.065
L 2.8.7 0.099 0.181
M 2.8.8.1 0.203 0.133
N 2.8.8.2 0.174 0.099

a) Which two elements have similar properties?
Explain (2mks)
………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………
b) What is the most likely formula of the oxide of L? (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………

c) Which element is a non – metal. Explain. (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
6. A student set- up the experiment below to collect gas K. The glass wool was heated before heating the zinc powder.

a) Why was it necessary to heat the moist glass wool before heating the zinc powder.(1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
b) What observation were made in the test-tube. (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
7. Using dots(•) and crosses ( x) to represent the outermost electrons, draw the structure to show the bonding in CO¬2 ( C = 6, O = 8) (3mks)

8. Sulphur is extracted from underground deposits by a process in which three concentric pipes are sank down to the deposits as shown below.

a) Name the process represented above. (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
b) What is passed down pipe J. (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
c) Name two allotropes of sulphur (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
9. Name the particles responsible for the electrical conductivity of
a) Graphite (1mk)

………………………………………………………………………………………………………………………………………………………………………………………………
b) Magnesium sulphate solution. (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
10. Study the diagram below and answer the questions that follow.

a) Identify gas Z (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
b) Write the chemical equation for the reaction which produced gas Z. (1mk)

c) State why the above experiment should be carried out in a fume chamber. (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………

11. The set- up below was used to investigate the rate of diffusion of different gases.

a) Explain why a coloured liquid is used in this experiment. (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
b) State and explain the observation made after 20 minutes. (2mks)
………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………
12. 25.0cm3 of 0.12M potassium hydroxide solution required 30.0cm3 of a solution of a dibasic acid (H2H) for complete neutralization. The acid contained 3.15g per 500cm3 solution Calculate:

a) The molarity of the acid solution. (1½ mks)
………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………
b) The relative formula of the acid. (1½ mks)

………………………………………………………………………………………………………………………………………………………………………………………………
13. Explain how a sample of CH3CH2OH could be distinguish from a sample of CH3 COOH by a chemical test. (2mks)
………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………

14. Study the flow chart below and answer the questions that follow.

a) State the observations made when ammonia gas is passed over heated copper(II)
oxide. (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
b) Identify :
i) Gas A (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
ii) Liquid B (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
15. Starting from calcium carbonate, describe how a solid sample of calcium sulphate can be
prepared. (3mks)
………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………
16. A gas, G is prepared in the laboratory by adding concentrated sulphuric (VI) acid to a compound C. Gas G is denser than air and dissolves in water to form a solution which is strongly acidic.

a) Name two gases that are likely to be G. (2mks)
………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………
b) Draw a diagram to show how gas G can be collected. (1mk)

17. Equal volumes of 2M dibasic acids X and Y were each reacted with excess zinc carbonates powder. The table below shows the volumes of the gas produced after 2 minutes.

Acid Volume of gas (cm3)
X 20
Y 80

a) Identify the gas produced. (1mk)

………………………………………………………………………………………………………………………………………………………………………………………………
b) Explain the difference in the volumes of the gas produced. (2mks)
………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………
18. Methane gas reacts with chlorine gas as shown in the equation below.
u.v
CH4(g) + Cl2(g) CH3Cl(g) + HCl(g)
light
Use the bond energies in the table below to calculate the enthalpy for the above reaction.

Bond Bond energy kJ/ mol
C – H 413
Cl – Cl 242
C – Cl 346
H – Cl 431

19. An equilibrium exists between the chromate ion (CrO2-4) and the dichromate (Cr2O2-7) as represented by the following equation.

2CrO2-4(aq) + 2H+(aq) Cr2O2-7(aq) + H2O(l)
(Yellow) (Orange)

State and explain the observation made on adding aqueous potassium hydroxide solution to the equilibrium mixture. (2mks)
………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………
………………………………………………………………………………………………
20. Below is a table of reduction potentials and volts of some half cells. The letters do not represent the actual symbols of the elememts but use them to answer the questions which follows.

Reaction Volts
A2+ + 2e A(s) -2.80
B+(aq) + e B (s) -1.50

2C +(aq) + 2e C2(s) 0.00
D2(g) + 2e 2D-(aq) + 3.20
G+ + e G(s) + 1.80

a) Select the species with the largest
i) Oxidising power. (1mk)

………………………………………………………………………………………………………………………………………………………………………………………………

ii) Reducing power (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
b) Calculate the electrode potential (e.m.f) for a cell constructed using half – cells of A and B.
(1mk)

21. A polymer has the following structure

A sample of this polymer is found to have a molecular mass of 5194.Determine the number of minomoers on the polymer.
(H = 1.0 , C = 12.0, N = 14.0) (2mks)

22. Malachite is an ore of copper. The main impurity is Iron(II) Oxide. Extraction of copper from its ore occurs in 3 stages; purification formation of electrolyte and electrolysis. The flow chart below shows the process of extraction.

a) Write the formula of the anion present in malachite. (1mk)

b) State how the main impurity in malachite is removed. (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
c) Explain why the method produces very pure copper metal. (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
23. The diagram below shows the behavior of radiation from a radioactive material in an electric field. Study it and answer the questions that follow.

a) Identify the radiations P and R
i) P (1mk)
………………………………………………………………………………………………
ii) R (1mk)
………………………………………………………………………………………………
b) Identify the charge on:
i) Plate A ( ½ mk)
………………………………………………………………………………………………

ii) Plate B ( ½ mk)

………………………………………………………………………………………………

24. Describe how a pure sodium chloride can be obtained from the mixute of iodine sodium chloride and sand. (3mks)
………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………
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25. a) Name two cations making water hard. (2mks)
………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………
b) By use of an ionic equation show how sodium carbonate makes permanent hard water soft.
(1mk)

26. State and explain what would be observed when hydrogen gas is passed over heated copper (II) oxide in a combustion tube. (3mks)

………………………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………………………
27. Solution R,S and T have PH values shown in the table below:

Solution pH value
R 1.0
S 6.5
T 8.0

a) What do you deduce about the nature of solution R? (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
b) Which solution would react most vigorously with sodium hydrogen carbonate. (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
c) Which solution is likely to be ammonia solution? (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………

28. a) Define the term solubility? (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………
b) Give two uses of solubility curves (2mks)
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29. a) Name two allotropes of sulphur. (1mk)
………………………………………………………………………………………………………………………………………………………………………………………………

b) Describe a suitable test for sulphite (SO32-) ions. (2mks)

………………………………………………………………………………………………………………………………………………………………………………………………
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Bureti Joint Evaluation -2012 Question Paper

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