(i) In extracting aluminium from aluminium oxide, the molten the electrolyge is a liquid mixture of cryolite `(Na_(3)AlF_(6))` Fluorspar `(CaF_(6))` and aluminium oxide (alumina) `(Al_(2)O_(3))`
(ii) The cathod and andoes are made of graphite.
(iii) During the electrolysis process, aluminium is deposited on the cathode on passing electric current.
(iv) Oxygen is liberated at the anode.
(v) Some of this oxygen react with the graphite to form carbon-dioxide gas then slowly buring away the anodes.
(vi) Thus, the anodes need to be replaced from time to time during the electrolysis of alumina.
