Question

Distinguish between electrolytic methods of reduction and refining.

Answer 1

Electrolytic Reduction

1. It is removal of oxide or halide from a metal.
2. Oxides of highly active metals like Na,K,Ca,Mg,Al are reduced by electrolytic reduction of their fused salts.
3. Oxides of these metals have great affinity for oxygen than carbon and cannot be reduced by carbon or CO or hydrogen.

Electrolytic refining of metals is the separation of residual impurities like Si and phosphorus.

1. Presence of other metals and non-metals like Si and phosphorus.
2. Unreduced oxides and sulphides of metals.

It depends upon:

1. Nature of metal
2. Purpose for which metal is to be obtained.
3. Nature of impurities present.
4. Impure metal is made anode while a thin sheet of pure metal is made cathode and electrolyte used is a salt of solution of a metal to be refined.