Question

Why is Cryolite added to Alumina during the extraction of Aluminium?

Answer 1

• Alumina (${\mathbf{Al}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{3}}$) is the purified Bauxite from which Aluminium is extracted by the process of electrolytic reduction.There is no conduction of electricity in the solid-state of Alumina. Its melting point is also very high (2348 K).
• Therefore, the addition of Cryloite (${\mathbf{Na}}_{\mathbf{3}}{\mathbf{AlF}}_{\mathbf{6}}$) having a small quantity of Fluorspar (${\mathbf{CaF}}_{\mathbf{2}}$) is done to Alumina to decrease the melting point of Alumina.
• Also, the addition of Cryolite to Alumina makes the electrolyte a good conductor of electricity.