Question

The following questions relate to the extraction of aluminium by electrolysis:

1. Give equation for the reaction that takes place at cathode.

Answer 1

1. To obtain aluminum, electrolysis of mixture is done with Graphite as cathode, and iron lined with graphite is done.
2. This process is known as Hall-Heroult process.
3. Here aluminum is obtained at cathode by reduction.
4. Reaction at the cathode: $4{\mathrm{Al}}^{+3}+12{\mathrm{e}}^{-}\to 4\mathrm{Al}$
5. Electrolysis of alumina : $2{\mathrm{Al}}_2{\mathrm{O}}_3\to 6{\mathrm{O}}^{-2}+4{\mathrm{Al}}^{+3}$