Question

Copper is purified by electrolytic refining of blister copper. The correct statement about this process is/are:

Answer 1

Hint: Blister copper is an impure form of copper containing sulphur. Copper is obtained by electrolytic refining of the impure copper. Try to write the chemical reactions taking place at the anode and the cathode. The electrolyte should have the copper ion so that it can be deposited as pure copper.

Complete answer:
Copper is purified by the process of electrolysis. Electricity is passed through solutions containing copper compounds like copper(II) sulphate. The positive electrode i.e. the anode is made from impure copper. On the other hand, pure copper strip is used as the negative electrode i.e. the cathode.
During electrolysis anode loses as copper dissolves into the solution as copper ions. The copper ions in the solution get deposited on the pure copper strip increasing the size of cathode. The impurities which are heavy and do not get oxidised settle down as anode mud.
The reactions happening at cathode and anode is give below:
Anode : $\text{Cu }\to \text{ C}{{\text{u}}^{2+}}\text{ + 2}{{\text{e}}^{-}}$ (oxidation)
Cathode : $\text{C}{{\text{u}}^{2+}}\text{ + 2}{{\text{e}}^{-}}\text{ }\to \text{ Cu}$(reduction)
Oxidation happens at the anode because electrons are lost in the reaction. Reduction happens at the cathode because electrons are gained in the reaction.
From the above explanation we can conclude that :
- Acidified copper(II) sulphate is used as an electrolyte in electrolysis process,
- Impure copper is used as anode,
- Pure copper strip is used as cathode,
- impurities settle down as anode mud.

Therefore, the correct answers are options (B), (C), (D).

Note:
The chief ore for obtaining copper is copper pyrites ($CuFe{{S}_{2}}$). Copper is obtained in the form of copper sulphide and copper oxide after the extraction process. This is called copper matte. Copper matte is used to obtain pure copper through electrolysis. Through electrolysis copper is obtained with a purity of about 99%.