Question

For each substance listed below, explain its significance in the extraction of aluminium.

(a) bauxite (b) Sodium hydroxide (c) Cryolite (d) Graphite

Answer 1

(a) Bauxite: Aluminium is extracted from its main ore bauxite Al₂O₃.2H₂O. It contains 60% Al₂O₃.

(b) Sodium hydroxide: Sodium hydroxide dissolves bauxite to form sodium meta aluminate, removes insoluble impurities from Al₂O₃ by forming red mud.

(c) Cryolite: Cryolite lowers the M.P. from 2050°C to 950°C and enhances conductivity.

(d) Graphite: Acts as cathode as well as anode.