Class 12th Chemistry 2017 Set3 Outside Delhi Board Paper Solution

Question 15

(a) Write the principle of electrolytic refining?

(b) Why does copper obtained in the extraction from copper pyrites have a blistered appearance?

(c) What is the role of depressants in the froth floation process?

Answer

(a) Electrolytic refining: It is the process of refining impure metals by using electricity. In this process, impure metal is made the anode and a strip of pure metal is made the cathode. A solution of a soluble salt of the same metal is taken as the electrolyte.



 

(b) Copper is extracted from its principal ore copper pyrites (CuFeS2). The ore is concentrated by froth flotation process. The molten copper is poured out and allowed to cool. The sulphur dioxide escaping from the melt gets trapped in the cooler parts of the surface giving a blistery appearance for copper and hence it is called blister copper.

 

(c) In the froth floatation process, the role of the depressants is to separate two sulphide ores by selectively preventing one ore from forming froth.

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