KCSE Past Papers 2014 Chemistry Paper 1 (233/1)

KCSE Past Papers Chemistry 2014

3.6 CHEMISTRY (233)

3.6.1 Chemistry Paper 1 (233/1)

1 Explain how the hotness of a Bunsen burner flame can be increased. (1 mark)

2 When dilute hydrochloric acid was reacted with solid B, a colourless gas which extinguished a buming splint was produced. When an aqueous solution of solid B was tested with a blue litmus paper, the paper turned red/ pink.

(a) Identify the anion present in solid B. (1 mark)

(b) Write an ionic equation for the reaction between solid B and dilute hydrochloric acid. (1 mark)

3 Dry ammonia gas was passed over heated lead (II) oxide and the products passed over anhydrous copper (II) sulphate as shown in the diagram below.

State:

(a) two observations made in the combustion tube. (2 marks)

(b) the property of ammonia gas shown in this experiment. (1 mark)

4 Starting with zinc sulphate solution, describe how a sample of Zinc oxide can be obtained. (3 marks)

5 Explain how conduction of electricity takes place in the following:

(a) iron metal; (1 mark)

(b) molten lead (ll) iodide. (1 mark)

6 100 cm3 of a sample of ethane gas diffuses through a porous pot in 100 seconds. What is the molecular mass of gas Q if 100 cm} of the gas diffuses through the same porous pot in l2l seconds under the same conditions?

(C = 12.0, H = 1.0) (3 marks)

7 (a) Draw and name the isomers of butyne. (2 marks)

(b) State one use of polystyrene. (1 mark)

8 Complete the nuclear reaction below:

imageee (1 mark) (b) State two uses of radioisotopes in health. (2 marks)

9 The table below shows the relative molecular masses and boiling points of pentane and ethanoic acid.

Explain the large difference in boiling point between ethanoic acid and pentane. (2 marks) 10 One of the ores of copper has the formula, CuFeS2.

(a) Describe how iron in the ore is removed during extraction of copper metal. (1 mark)

(b) State two environmental problems associated with extraction of copper metal. (2 marks)

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

Identify Z and M. (2 marks)

Z …………………………………………………. ..

M …………………………………………………….

12 The table below shows the pH values of solutions A, B, C and D.

Solution

Select solutions in which a sample of lead (ll) hydroxide is likely to dissolve. Give reasons for each solution selected. (3 marks)

13 100 cm3 of 0.05 M sulphuric (VI) acid were placed in a flask and a small quantity of anhydrous sodium carbonate added. The mixture was boiled to expel all the carbon (IV) oxide. 25 cmi of the resulting solution required 18 cm3 of 0.l M sodium hydroxide solution to neutralise it. Calculate the mass of sodium carbonate added. (Na : 23.0; O : 16.0; C = 12.0) (3 marks)

14 When 20 cm3 of l M sodium hydroxide was mixed with 20 cm3 of 1 M hydrochloric acid, the temperature rose by 6.7 “C. Assuming the density of the solution is l g/cm3 and the specific heat capacity of the solution is 4.2 J g” k”;

(a) calculate the molar heat of neutralisation; (2 marks)

(b) when the experiment was repeated with 1 M ethanoic acid, the temperature change was found to be lower than that with 1 M hydrochloric acid. Explain. (1 mark)

15 Study the set-up below and answer the questions that follow.

(a) Write an equation for the reaction between ammonia and copper (II) oxide. (1 mark)

(b) During the experiment, the colour of the contents in the water trough changed. State the colour change observed and give an explanation. (2 marks)

16 A measuring cylinder fitted with moist steel wool was inverted in a trough of water as shown in the diagram below.

(a) State and explain the observations made on the:

(i) moist steel wool after four days. (1 mark)

(ii) water level in the measuring cylinder after four days. (1 mark)

(b) What would be the effect of using steel wool moistened with salty water? (1 mark)

17 In an experiment on rates of reaction, potassium carbonate was reacted with dilute sulphuric

(VI) acid.

(a) What would be the effect of an increase in the concentration of the acid on the rate of the reaction? (1 mark)

(b) Explain Why the rate of reaction is found to increase with temperature. (2 marks) 18 Use the part of the periodic table given below to answer the questions that follow.

(Letters are not the actual symbols of the elements).

(a) Identify the element that forms giant covalent structures. (1 mark)

(b) Identify one element that does not form compounds. (1 mark)

(c) Write the formula for the nitride of M. (1 mark)

19 Draw a set up that can be used to separate a mixture of sand and iodine. (3 marks)

20 In the contact process, during the production of sulphur (VI) oxide, a catalyst is used.

Give two reasons why vanadium (V) oxide is preferred to platinum. (2 marks)

21 Given that the atomic number of Y is 13 and that of Z is 9:

(a) write the electronic arrangement of Y and Z; (1 mark)

(b) draw the dot ( .) and cross (X) diagram for the compound fomied by Y and Z. (1 mark)

22 The set up below was used to separate a mixture of methanol and propanol. Study it and answer the questions that follow.

(a) State the function of X.(1 mark)

(b) Which liquid will collect first in the beaker? Give a reason.(2 marks)

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

(a) Name the process in step l.(1 mark)

(b) Identify the reagent in step II.(1 mark)

(c) Give one use of ethane.(1 mark)

24 (a) A student electrolysed dilute sodium chloride solution using inert carbon electrodes. Name the products at:

(i) anode;

(ii) cathode.

(2 marks) (b) If the experiment was repeated using concentrated sodium chloride instead of dilute sodium chloride solution, Write the half equation at the anode. (1 mark)

25 An organic compound had the following composition 37.21% carbon, 7.75% hydrogen and the rest chlorine. Detemiine the molecular formula of the compound, given that the molecular mass of the compound is 65. (C : 12.0; H : 1.0; Cl : 35.5). (3 marks)

26 Cotton is a natural polymer. State one advantage and one disadvantage of this polymer. (2 marks)

Advantage: …………………………………………….. ..

Disadvantage: …………………………………………… ..

27 (a) Name a suitable solvent for extracting an indicator from flowers; (1 mark)

(b) Give a reason Why the solvent named in (a) above is used. (1 mark)

28 A student used the set up below to prepare a sample of nitrogen gas.

(a) State the function of potassium hydroxide in the set up. (1 mark)

(b) Give a suitable metal M for use in the combustion tube.

(c) Give a reason why the nitrogen gas obtained is not pure. (1 mark)

29 (a) What is meant by the term radical? (1 mark)

(b) The table below contains atoms that form common radicals. Complete the table to show radicals formed from various atoms.

(a) State and explain two observations made in the gas jar after some time. (2 marks)

(b) Write the equation for the reaction between chlorine and hot concentrated potassium hydroxide. (1 mark)

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