Question

Write the electrode reactions in the process ofelectrolytic reduction of alumina.

Explain : Anodes need to be replaced from time to time during this electrolysis.​

Answer 1

Answer:

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. 4Al3+ + 12e- → 4Al (aluminium metal at the (-)cathode) reduction.

Answer 2

Answer:

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. 4Al3+ + 12e- → 4Al (aluminium metal at the (-)cathode) reduction.

Explanation:

During electrolysis of alumina, the oxygen liberated at the carbon anode reacts with graphite rods (carbon anode) and forms carbon dioxide. (2) As the anodes gets oxidised during electrolysis of alumina, they are continuously eroded. Hence, it is necessary to replace anodes from time to time.