Question

Explain the principle of the method of electrolytic refining of metals. Give an example.

Answer 1

Crude metal is used as anode and the pure metal is used as cathode and the soluble salt of the same metal is used as the electrolyte. We can extract and purify the impure metals through the process of electrolysis. The process needs electric current to pass through the solution.

Complete step by step answer:
Electrolytic refining is a method that is used for extraction and purification of impure or crude metals through the process of electrolysis. In this method, crude metal is used as the anode, and the pure metal is used as cathode and the soluble salt of the same metal is used as the electrolyte. Now, when the electric current is passed through the solution, the pure metal deposits upon the cathode, and the impure metal dissolves from the anode into the solution, leaving the impurities below the anode, which is known as anode mud. For example, we can take electrolytic refining of copper.
In the method of electrolytic refining of copper, the impure copper (Cu) is used as the anode in the electrolyte solution of copper sulphate (CuSO4), and sulfuric acid (H2SO4) and the sheet of pure copper is used as the cathode. Now, when the current is passed, Cu2+ ions (positive copper ions) get attracted to the negative cathode with electrons and thereby depositing themselves as neutral copper atoms. Thus, we can get more pure copper metal in the cathode. Simultaneously, copper atoms of the positive anode give up electrons and dissolve into the electrolyte solution as the copper ions.
The reactions of the cathode and anode are as following:
At cathode:
$Cu^2 + 2e^ - \to Cu$
At anode:
$Cu - 2e^ - \to Cu^{2+}$

Note:
It is necessary to choose the proper electrolyte and its appropriate conditions to use so that the reactions in both the anode and cathode proceed with high efficiency and also, none of the impure metals can move from the anode to the cathode.