Question

Write the electrode reactions involved in Hall-Heroult’s process.

Answer 1

At cathode: \[\ce{Al^{3+} + 3e- -> Al}\]

At anode: \[\ce{2O^{2-} -> O2 + 4e-}\]

The oxygen formed reacts with the carbon anode:

\[\ce{C + O2 -> CO2}\]

Overall reaction: \[\ce{2Al2O3 + 3C -> 4Al + 3CO2}\]