CBSE Class 10 Answered

Electrolytic refining:- Many metals, such as copper, zinc, tin, nickel, silver, gold etc. are refined by electrolysis. In this process, the impure metal is made the anode and a thin strip of pure metal is made the cathode. The solution of the metal salt is used as an electrolyte. When current passes through electrolyte, the pure metal from the anode dissolves into the electrolyte. An equivalent amount of pure metal from the electrolyte is deposited on the cathode. The insoluble impurities settle down at the bottom of the anode and are known as anode mud whereas the soluble impurities go into the solution.

 

For example: In electrolytic refining of copper, the electrolyte is a solution of acidified copper sulphate. The anode is impure copper, whereas the cathode is a strip of pure copper. On passing electric current, pure copper is deposited on the cathode.