Explain the principle and working of the method of electrolytic refining of metals. Give one example.

Explanation

In this method, the impure metal is made as anode. A strip of the same metal in pure form is used as cathode. They are put in a suitable electrolytic bath containing soluble salt of the same metal. The more basic metal remains in the solution and the less basic ones goes to the anode mud.
Example : Copper is refined using the an electrolytic method. Anodes are of impure copper and pure copper strips are taken as cathodes. The electrolyte is acidified solution of copper sulphide and the net result of electrolysis is the transfer of copper in pure form from the anode to the cathode. Electrode reactions are given as under :
Anode : `Cu to Cu^(2+) +2e^(-)`
Cathode : `Cu^(2+) +2e^(-) to Cu`.