Question

The cathode used to extract pure metal from the ore corundum by electrorefining is ________.

• A. Inert graphite
• B. Pure aluminium
• C. pure iron
• D. pure copper

Answer 1

The correct option is A

Inert graphite

Corundum is an ore of aluminium. Using a suitable method like the Hall-Heroult process, the impure ore is refined into a pure form of alumina, which is then subjected to electrolysis. The pure alumina - which is still technically an ore - gets reduced electrolytically to yield molten aluminium metal. The metal usually doesn't require any further refining because the molten aluminium is already 99.5 - 99.8 % pure. The electrodes used in the electrolytic reduction are made of inert graphite.