Question

Explain electrolytic refining with an example.

Answer 1

1. The impure metal is taken as anode and pure metal is taken as cathode. 

2. They are put in a suitable electrolytic bath containing soluble salts of same metal. 

3. The required metal gets deposited on the cathode in the pure form. 

4. The metal constituting the impurity goes as the anode mud.

Electrode reactions : 

At Anode : M → Mⁿ⁺ + ne^–

At Cathode : Mⁿ⁺ + ne^– → M (M pure metal); where n = 1, 2, 3,

Examples : 

1. In order to refine copper, impure copper is taken as anode and pure copper strips are taken as cathode. 

2. The electrolyte is an acidified solution of copper sulphate. 

3. As a result of electrolysis copper in pure form is transferred from anode to cathode.

At Anode : Cu → Cu²⁺ + 2e^-

At Cathode : Cu²⁺ + 2e^- → Cu

4. The soluble impurities go into the solution, whereas insoluble impurities from the blister copper deposited at the bottom of anode as anode mud.