Question

Write the formula of cryolite. Give its function in the extraction of aluminium.

Answer 1

Cryolite:

• Cryolite is a white or colourless mineral composed of sodium and aluminium fluorides.
• The formula of cryolite is ${\mathrm{Na}}_3{\mathrm{AlF}}_6$.

The function of cryolite in the extraction of aluminium:

• Cryolite is used in the electrolytic extraction of aluminium to lower the melting temperature of the mixture to about 1140 K.
• Cryolite increases the electrical conductivity of the mixture.