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6. a) Given pure samples of sodium carbonate, chloride, nitrate, sulphite, and 

 sulphate, give one test by which the negative (acid) radical in each 

 may be identified. 



b) Write equations for the reaction of each of the above substances with 

 concentrated sulphuric acid at room temperature. 



Part II 

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



6. a) Using the ionization theory, explain the equilibrium in a dilute solution 



of sodium chloride. If two platinum electrodes are introduced and 

 a current of electricity passed, explain in detail the changes at the 

 cathode. 



h) Compare the degree of ionization of (1) hydrochloric acid and acetic 

 acid, (2) ammonium hydroxide and potassium hydroxide, in water 

 solutions of the same concentration. 



7. a) What is a saturated solution of a solid in a liquid? 



b) How does increasing the temperature affect the solubility of solids in 

 liquids ? 



£) In what two ways could a saturated solution of sodium chloride in water 

 be prepared? How could you satisfy yourself that the solution is 

 just saturated in both cases ? 



8. a) State the Law of Multiple Proportions. 



b) Give two substances to illustrate the above law with the percentage 

 composition in each case. 



9. One hundred Uters of dry air at 20° C. and at 760 mm. contain 0.078 gram of 



carbon dioxide. What is the proportion by volume of carbon dioxide 

 present in the air ? 

 Note — One liter of carbon dioxide at 0' C and 760 mm. weighs 1 .98 grams. 



10. a) A small flask contains ferric chloride (yellow) strongly acidified with hydro- 

 chloric acid. A quantity of iron tacks is added, and the flask is closed 

 in such a manner as to permit the escape of gas and to prevent the 

 entrance of air. How do you explain the loss of color? Write an 

 equation for the reaction. 



b) On exposure to air the yellow color of the solution is gradually restored. 

 Account for the result. Write an equation for the reaction. 



(THIS EXAMINATION IS CONTINUED ON PAGE 3) 



