Question

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

Answer 1

Electrolytic refining : This method is based upon the phenomenon of electrolysis. The crude metal is made the anode whereas a thin sheet of pure metal is made cathode. Electrolyte is the solution of some salt of the metal. On passing electricity, the metal from the anode goes into solution as ions due to oxidation while pure metal gets deposited at the cathode due to reduction of metal ions. The less electropositive impurities settle down below the anode as anode mud.

For example, electrolytic refining of Cu using impure copper anode, pure copper cathode and aq. $CuS{O}_4$ electrolyte is shown below :

At anode : $Cu\left(s\right)\to C{u}^{2+}\left(aq\right)+2e^{-}$

At cathode: $C{u}^{2+}\left(aq\right)+2e^{-}\to Cu\left(s\right)$