Question

In electrolytic reduction of Alumina the graphite anode is gradually consumed.Give reason

Answer 1

Graphite rod is used as an anode and graphite line iron as cathode during the electrolysis of alumina. During the electrolysis aluminium is liberated at the cathode and oxygen at the anode. This oxygen reacts with the graphite anode to for CO and CO2 preventing the oxygen evolved from oxidizing aluminium.Thus the role of graphite in electrometallurgy of aluminium is to prevent the liberation of oxygen so that the aluminium is not oxidized by oxygen. Graphite being cheaper is also an advantage.