Question

Distinguish between electrolytic methods of reduction and refining.

Answer 1

1. Electrolytic Reduction:

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

Electrolytic Refining:

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.

2. It depends upon:

1. Nature of metal.
2. Purpose for which metal is to be obtained.
3. Nature of impurities present.

3. Impure metal is made anode, while a thin sheet of pure metal is made cathode and the electrolyte used is a salt of solution of a metal to be refined.