CHEMISTRY FORM THREE TERMINAL EXAMINATION

5. During laboratory experiment, a student used petrol to heat water in a container. The initial mass of the
spirit burner with petrol was 120 g and the final mass after burning was 100 g. The heat produced was
used to heat 2.5 litres of water. The heat value of petrol is 43640 KJ/kg and the specific heat capacity of
water is 4.2 KJ/kg°C
(a) Determine the mass of petrol that was burnt during the experiment
(b) Calculate the total heat energy released by the petrol
(c) Determine the temperature change of the water if all the heat produced was used to heat the
water
(d) State two reasons why the actual temperature rise in a real experiment may be lower than the
calculated value

6. (a)A form two student went to the laboratory aimed to perform a certain experiment by using dark grey
solid on deflagrating spoon, ignited at high temperature and then the spoon was lowered into the gas jar
containing oxygen.
(i) Identify the dark grey solid that burned
(ii) Write the balanced chemical equation in the process
(iii) Explain the nature of the product in terms of acidic or basic properties
(b) (i) Suppose there is no hydrogen in the universe. What would happen? (two points0
(ii) Itisfactthatperformanceisdirectlyrelatedtotheaspectsofthatsubstance.Justify the statement based in
hydrogen gas. (two points)

7. (a) Some gases are prepared in as special room called fume chamber. How the room support the
phenomena? (3 points)
(b) One of the first aid procedure given to the causality is Resuscitation. As a form three student clarify
the process and then deduce any two vitals of the process to the victim.

8. Briefly explain how you can differentiate a solution and suspension by their appearance
(b) The time taken for sugar to dissolve in cold tea differs from that in hot tea. Explain.
(c) Explain why cooking oil and water are termed as immiscible liquids

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SECTION C (30 Marks)

Answer only TWO (2) question from this section.

9. The research has revealed that although acids and bases are dangerous to mankind as they are corrosive
in nature, yet they are useful to lives of a man. Give four reasons as to why they are useful to man.
10. Dunia Nzima Matatizo was ordered by his father to take the hoes and panga inside the house before
going to sleep. A boy forgot the order given by his father. He left them outside and went to sleep.
During the morning he found the equipment have been covered by the reddish-brown substance.
(a) What is the name given to such reddish substance formed on the surface of the equipment?
(b) Write a balanced chemical equation representing the reaction described above?
(c) Identify the type of reaction represented by the equation written in (b) above?
(d) Explain any four methods which can be used to prevent the chemical process described in (b)
above.
11. (a)What do you understand by the following terms as used in chemistry?
(i) Empirical formula
(ii) Molecular formula
(iii) Structural formula
(b) A certain compound Q is made up of elements Hydrogen(H), Sulphur(S)and Oxygen
(O)withthepercentagecompositionof2%,32%andtherestXrespectively.Ifthe molecular mass of
compound Q is 98, calculate:
(i) The percentage composition X
(ii) The molecular formula of compound Q
(iii) WritethebalancedionicequationwhenthecompoundQreactwithsodiumhydroxide
(c) Name the ions found in the following substances
(i) Pb(NO3)2
(ii) NH4OH
(d) Using electronic diagram show how CO2compoundis formed