QUESTIONS AND ANSWERS 31 



ZINC 



Name three preparations of zinc that are used in medicine and write 

 the chemical formula of each. 

 Zinc sulphate, ZnSO^ ; zinc chloride, ZnCl^ ; zinc oxide, ZnO. 



Describe a method of preparing zinc sulphate. 



Dissolve zinc in dilute sulphuric acid. 

 H2SO4 + Zn = ZnSO^ + 2H. 



How can Epsom salts be distinguished from zinc sulphate? 



By testing with potassium f errocyanide. Zinc ferrocyanide will 

 be thrown down as a white precipitate. No precipitate is formed 

 with magnesium. 



BORON 



Give the names of the principal compounds and the chemical impor- 

 tance in medicine of boron. 

 Boric acid, H3BO3. 



Sodium borate, NajB^O^jlOHjO (borax). 



Boric acid and borax are mild, harmless, non-irritating anti- 

 septics and are very serviceable in surgery. 



ALUMINUM 



Give the properties of aluminum and mention its important salts. 



Aluminum is a bluish-white, brilliant metal; malleable and 

 ductile ; specific gravity, 2.583. It is an excellent conductor of heat 

 and electricity. It oxidizes superficially in the air and has the 

 valuable properties of strength and lightness combined. 



Aluminum sulphate is its most important salt. This combines 

 with the sulphates of the alkaline metals to form a class of double 

 salts, known as alums. Potassium alum is the commonest example. 



BISMUTH 



Give (a) the symbol, (b) atomic weight, (c) occurrence in nature, and 

 (d) the compounds used in medicine of bismuth. 



(a) Bi. (b) 206.5. (c) Rare, occurs as an oxide and sulphide, 

 (d) Bismuth subnitrate, subgallate, subcarbonate, subsalicylate and 

 citrate. 



IRON 



How does iron occur in nature? 



Iron is found in small quantities in nearly all forms of rocks, 

 clay, sand and earth, and in plants and blood. Rarely found free 



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