Question

Give reasons for the following : (i) Alumina is dissolved in cryolite for electrolysis instead of being electrolysed directly.

Answer 1

The mixture of cryolite and aluminium oxide has a lower melting point than pure aluminium oxide. This means a lower amount of energy is required to establish effective conditions for electrolysis and thus makes it more cost effective.

Molten cryolite serves as a solvent for the molten aluminium oxide and increases the conductivity of the solution.