Question

(a) Give the chemical name and formula of 'cryolite'.
(b) What is the function of cryolite in the extraction of aluminium, other than acting as a solvent for bauxite?

Answer 1

(a) The chemical name for cryolite is sodium aluminium fluoride and its chemical formula is ${\mathrm{Na}}_3{\mathrm{AlF}}_6$.

b) Cryolite acts as a solvent for the electrolytic mixture. It helps dissolve fused pure alumina and helps melt the mixture at $950{}^{\mathrm{o}}C$ instead of $2050{}^{\mathrm{o}}\mathrm{C}$ (melting point of alumina). Thus, at this temperature, a molten alumina mixture is obtained and it conducts electricity easily.