Cryolite (Na3AlF6) and fluorspar (CaF2) are added to the electrolytic mixture containing pure alumina.

Question

Give scientific reason for the following:

Cryolite (Na₃AlF₆) and fluorspar (CaF₂) are added to the electrolytic mixture containing pure alumina.

Answer 1

(1) Alumina has very high melting point ( > 2000 °C). Cryolite (Na₃AlF₆) and fluorspar (CaF₂) lower the fusion temperature of the mixture containing alumina from 2000 ° C to 1000 ° C, thereby saving electrical energy.

(2) They increase the conductivity and the mobility of the fused mixture. Hence, cryolite and fluorspar are added to the electrolytic mixture containing pure alumina.