Question

Write scientific reason.

Anodes need to be replaced from time to time during the electrolysis of alumina.

Answer 1

In the electrolysis of alumina, graphite rod is used as anode.

• During the electrolytic reduction of alumina, aluminium is produced at the cathode and oxygen gas is evolved at the anode.
• This gas reacts with the graphite rods (anode) and forms carbon dioxide.

Thus, the graphite rods are continuously eroded. Hence, anodes are replaced from time to time during the electrolysis of alumina.