Question

Describe the following:
(i) The role of cryolite in electrometallurgy of aluminium.
(ii) The role of carbon monoxide in the refining of crude nickel.

Answer 1

(i) The role of electrolyte is two-fold:

 * It covers the melting point of the mixture to about 1250 K.

* It increases the electrical conductivity of the mixture.

(ii) When nickel is heated with carbon monoxide it forms a volatile compound tetracarbonyl nickel, Ni(CO)₄ which on further heating at higher temperature decomposes to give pure nickel.