Set 8 Chemistry [Paper] 2

1 SECTION A (60 Marks) Answer only three questions from this section . 1. Tin and lead are members of group (IV) of the periodic table. (a) Write: (i) The outer most electronic configuration of the elements (1 mark ) (ii) The formulae of the common oxides of lead (1 ½ marks) (b) Write equations of reactions to show the oxides of lead in (a) (ii) are formed (4 ½ marks) (c) Describe the reactions of tin and lead with: (i) Sulphuric acid (ii) Sodium hydroxide (8 marks) (d) Name one reagent that can be used to distingu ish between the following pairs ions. In each case state what would be observed and write equation(s) for the reaction(s). (i) Pb2+ and Sn2+ (ii) Sn2+ and Sn4+ (5 marks) 2. Chemical Kinetics deduces the order of reaction and its molecularity . (a) Explain what is meant by the following terms: (i) Order of reaction (2 marks) (ii) Molecularity of a reaction (2 marks) (b) Describe an experiment to show that iodination of propanone follows a zero order reaction with respect to iodine . (7 marks) (c) Sucrose is hydrolysed in acidic medium to give a mixture of glucose and fructose. 2 The graph below shows a plot of logarithm of the molar concentration of sucrose remaining at intervals of time. Where 11 22 12 OHCInSIn Using the graph, determine the: (i) Original concentration of sucrose (1½ marks) (ii) Order of reaction (2 marks) (iii) Velocity constant for the reaction (1½ marks) (iv) Half-life for the reaction (2 marks) (d) State the conditions under which the reaction in (c) above is overall first order. (2 marks) 3 3. Complete the following equations and in each suggest a mechanism for the reaction. (a) (4½ marks) (b) (3 marks) (c) (4½ marks) (d) (4 …