Answer to Question #67346 in Inorganic Chemistry for Janco

Question

Can electrolysis be performed on aluminium oxide without the presence of carbon at its melting point?

Answer 1

Aluminium oxide (Al2O3) is an ionic compound. When it is melted the Al3+ -and O2- -ions are free to move and conduct electricity.
Electrolysis of the alumina/cryolite solution gives aluminium at the cathode and oxygen at the anode. The overall reaction is
2〖Al〗_2 O_3→4Al (l)+3O_2 (g)
Oxygen is given off at the positive carbon anode.
Carbon dioxide is also given off at the carbon anode because hot oxygen reacts with the carbon anode to form carbon dioxide gas.
C (s)+O_2 (g)→CO_2 (g)

Answer: It can’t, the electrolysis requires a large amount of energy because aluminium's affinity for oxygen. However, Carbon binds Oxygen in dioxide gas.