Aluminium is normally extracted from its the ore (mineral) bauxite
that contains aluminium
Bauxite is not soluble in water and must be melted to release its ions.
Cryolite (sodium hexafluoroaluminate Na3AlF6)
is added to lower the melting point of aluminium oxide to 9000C
from 20450C. Using carbon
electrolysed (subjected to electrolysis).
available in the electrolyte
are aluminium Al3+ ions and oxide O2- ions.
The aluminium cations
Al3+ migrate to the cathode (carbon
lining) and are discharged.
of Electrons ⇨
Reduction happens at the cathode.
oxide anions O2-
migrate to the anode (carbon
electrodes) and are discharged.
Loss of Electrons ⇨
Oxidation happens at the anode.
The overall equation for the above is
→ 4Al(l) +
anode has to be replaced from time to time as it is corroded in the