Question

In the electrolytic reduction of alumina, the electrolyte is covered with coke powder because, if :

• A. prevents oxidation of aluminium formed
• B. reacts with aluminium forming aluminium carbide
• C. prevents heat loss from electrolyte
• D. None of the above

Answer 1

The correct option is C prevents heat loss from electrolyte

The electrolyte is a molten bath of cryolite and dissolved alumina. Cryolite is a good solvent for alumina with low melting point. The molten electrolyte is maintained at high temperature inside the insulating cell by using high amount of coke powder or dust to prevent the heat loss.