IQII 



CHEMISTRY 



Friday 3-4S-5-45P- m - 



A teacher's certificate covering the laboratory instruction must be presented as part 

 of the examination. 



Answer seven questions as indicated below. No extra credit will be given for more 

 than seven questions. 



GROUP A 

 Answer two questions from this group 



1. (a) Describe briefly practical processes for bringing about any two of the 



following transformations: 



(1) potassium nitrate to potassium sulphate 



(2) calcium carbonate to calcium hydroxide 



(3) sulphur to hydrogen sulphide 



(4) lead nitrate to lead sulphate. 



(b) Explain in detail how you should prepare any three of the following 

 in the laboratory: lime water, sulphur dioxide, ammonium nitrate, nitric 

 oxide, concentrated hydrochloric acid, charcoal. 



2. (a) Describe a method, involving chemical change, for distinguishing between : 



(1) zinc and zinc oxide 



(2) hydrogen and ammonia 



(3) sodium carbonate and sodium sulphate. 



(b) Describe briefly two distinct experimental methods for showing the 

 elements of which water is composed. 



3. (a) What is a saturated solution of a salt ? 



(b) In general, will a given amount of water dissolve more of a salt at a lower 

 or at a higher temperature ? 



(c) Describe two ways in which a solution of sodium chloride in water, sat- 

 urated at room temperature, may be prepared. 



(d) How may a soluble salt be freed from soluble impurities ? 



GROUP B 

 Answer both questions in this group 



4. (a) Complete the following equations, using formulae throughout: 



1 i ) Silver nitrate (solution) + zinc = 



(2) Sulphur dioxide + oxygen = 



(3) Sodium sulphate +barium chloride = 



(4) Sodium hydroxide + carbon dioxide = 



(5) Manganese dioxide-}- hydrochloric acid = 



(b) Illustrate by equations three general methods for making the chlorides 

 of metallic elements. 



5. (a) How much sodium chloride would be necessary to produce 10 grams of 



dry sodium sulphate ? 



(b) What volume of oxygen under standard conditions could be obtained 



from 10 grams of potassium chlorate ? 

 O = i6, Na=2 3 , 8 = 32, 1=35.5, K=3 9 . 

 One liter of oxygen at o and 760 mm. weighs i . 43 grams. 



18 



