Question

During electrolytic refining of copper
(a)- Pure copper acts as anode
(b)- Pure copper acts as cathode
(c)- Impure copper acts as anode
(d)- Impure copper acts as cathode
A- (a), (b)
B- (b), (c)
C- (a), (d)
D- (b), (d)

Answer 1

Hint: While electrolytic refining, the amount of anode decreases, and the amount of cathode increases. Impurities of the metals settle as anode mud or anode sludge.

Complete step by step answer:
A large number of metals such as copper, silver, gold, lead, nickel, etc., are refined by electrolytic refining.
Electrolytic refining is a process in which a block of impure metal is used as anode whereas the pure metal strip is called the cathode. The solution of electrolyte which is mostly the double salt of the metal is used for suspension of electrodes. As soon as the electric is passed, the metal ions in the electrolyte start to deposit at the cathode. And the same amount of metal dissolves from the anode and goes into the electrolyte solution as metal ions,
\[Anode:M(s)\to {{M}^{n+}}(aq)+n{{e}^{-}}\]
\[Cathode:{{M}^{n+}}(aq)+n{{e}^{-}}\to M(s)\]
In the case of copper, crude copper metal, i.e., blister copper is made the anode, a thin sheet of pure copper is made the cathode while copper sulfate solution acidified with sulphuric acid is taken as the electrolyte. The reaction of transfer of pure form of copper from the anode to the cathode can be written as:
\[Anode:Cu(s)\to C{{u}^{2+}}(aq)+2{{e}^{-}}\]
\[Cathode:C{{u}^{2+}}(aq)+2{{e}^{-}}\to Cu(s)\]
Hence, the correct option is B- (b),(c)

Note: Don't get confused about the electron transfer at anode and cathode. At the anode, the electrons are released whereas at cathode the electrons are absorbed. The voltage applied for electrolysis is such that the impurities if metal settle down under the anode as anode mud or anode sludge.