Part II 

 (Answer five questions from Part II. Extra questions will receive no credit.) 



6. a) State how you would prove whether a certain salt solution is unsaturated, 



saturated, or supersaturated. 

 b) How do chann;es in temperature and pressure respectively change the 

 solubility in licjuids of gases and of solids ? 



7. a) Mention three important differences between the water solutions of 



electrolytes and those of non-electrolytes. How are these differences 

 explained ? 

 b) Explain fully in terms of the ionization theory the electrolysis of a solution 

 of copper sulphate. 



8. A balloon requires for adequate inflation 5,000 gram-molecular volumes (or 



an equal number of gram-molecules) of hydrogen, measured at normal 

 temperature and pressure. What is the cost of inflating such a balloon 

 if scrap iron at 1 cent per kilogram and sulphuric acid, containing 20 per 

 cent of H2SO4, at 4 cents per kilogram, are used for generating the hydro- 

 gen? (Fe=56, H = l, S=32, 0=16.) 



9. c) Describe the production of ammonia either by the Haber process, or from 



calcium cyanamide. (All equations are required.) 

 b) Write down in parallel columns fn-e specific physical properties of am- 

 monia, and three specific chemical properties. 



10. a) Describe a test or tests to distinguish (1) between oxygen and nitrous 



oxide, (2) between hydrogen and carbon monoxide, (3) Ijetween nitrogen 

 and carbon dioxide. 

 b) State briefly the effect of inhaling each of these gases in the pure state. 



11. c) How would you determine whether a given sample of ammonia gas con- 



tained air ? 

 b) Give tests for free chlorine, bromine, and iodine respectively; give also a 

 test for the ions of the same elements. 



12. Describe two important chemical industries depending directly or indirectly 



on electrical energy. 



13. a) Describe the "burning" of limestone. Make a diagram of a kiln, and 



indicate its operation. 



b) Distinguish between quicklime, slaked lime, air-slaked lime, lime water, 



and milk of lime. 



c) What is meant by "destructive distillation"? By applying this process 



to soft coal, what products are obtained ? What products are obtained 

 by applying the process to wood ? 



14. a) What is "sterhng" silver, and what acid should be used to dissolve it? 



ib) How may pure silver be obtained from this solution ? (c) State how 

 articles of baser metal are plated with silver, and how mirrors are silvered. 

 [d) What compound of silver is used in indelible ink ? Explain the 

 chemical changes involved in its use. 



15. 1.0085 grams of pure tin foil were oxidized with nitric acid, and the final 



weight of the highly ignited oxide was 1 .2790 grams. From the data sub- 

 mitted, find the percentage composition and the simplest formula of this 

 oxide of tin. (Sn = 1 19, = 1(3.) 



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