Question

(a) On which factors does purification of metals depend?

(b) Name the methods used for purification.

(c) How is electro-refining done?

Answer 1

(a) The purification depends upon:

1. Nature of metal.
2. Nature of impurities present in the metal.
3. Purpose for which metal is to be used

(b) Methods used for purification are:

1. Distillation
2. Liquation
3. Oxidation
4. Electro-refining

(c) The impure metal is made the anode, while a thin sheet of pure metal is made the cathode. Electrolyte used is a salt solution of a metal which is to be refined. Pure metal deposits at the cathode and impurities settle down forming anode mud.