Set 16 Chemistry [Paper] 2

1 SECTION A (60 Marks) Answer only three questions from this section . 1.(a) (i).What is meant by the term colligative property . (02 marks) (ii).State any two colligative properties of a solution . (01 mark ) (iii).State any two limitations of colligative properties stated in (a) (iii) above. (02 marks) b) Describe how molecular mass of cane sugar can be determined using the depression of freezing point method . (07 marks) c) The table below shows the freezing points of various solutions of cane sugar in solvent Y . Mass of cane sugar[g/100g solvent Y] 26 24 66 78 118 148 173 Freezing point/ᵒC 5.11 4.87 4.51 4.33 3.73 3.28 2.91 Plot a graph of freezing point against mass of cane sugar and use it to determine: (@02½ marks) (i) Freezing point of solvent Y. (ii) Freezing point constant for solvent Y [RMM of cane sugar = 342] d) State and explain how the freezing point of the solution would be affected if cane sugar associates in solvent Y . (02 marks) e) Explain why the method of depression of freezing point is not suitable for determination of relative molecular mass of very large molecules . (01 mark ) 2 2. An organic hydrocarbon, R on complete combustion yielded 13.20g of carbon dioxide gas and 2.70g of water . When 9.40g was vapourized at a temperature of 273K and a pressure of 760mmHg , it occupied a volume of 2.7 x 10-3m3. a) Calculate the empirical formula of organic hydrocarbon, R. (02½ marks) b) Determine the molecular formula of organic hydrocarbon, R. (03 mark s) c) Organic hydrocarbon, R burns with a sooty flame. Identi fy organic hydrocarbon, R. (01 mark) d) Discuss the reactions of organic hydrocarbon, R with: (i) Bromine. (04 marks) (ii) Propene. (04 marks) (iii) …