Question

Which of the following statements explains why a mixture of aluminium oxide and molten cryolite is used in the electrolysis cell for extracting aluminium from aluminium oxide?

A) Cryolite lowers the melting point of aluminium oxide, facilitating its electrolysis.
B) Cryolite enhances the conductivity of the electrolyte, allowing efficient extraction of aluminium.
C) Cryolite prevents the oxidation of aluminium during the electrolysis process.
D) Cryolite acts as a catalyst, accelerating the decomposition of aluminium oxide.

Answer 1

Cryolite lowers the melting point of aluminium oxide, facilitating its electrolysis.

Step-by-step explanation:

The correct statement explaining why a mixture of aluminium oxide and molten cryolite is used in the electrolysis cell for extracting aluminium from aluminium oxide is option A) Cryolite lowers the melting point of aluminium oxide, facilitating its electrolysis.

In the Hall-Heroult process, a molten mixture of aluminium oxide and cryolite is used as the electrolyte. Cryolite, which has a lower melting point than aluminium oxide, helps to reduce the overall melting point of the mixture. This is important because the resulting mixture needs to be in a molten state for electrolysis to take place.

By lowering the melting point, cryolite facilitates the electrolysis process, making it easier to extract aluminium from aluminium oxide. The electrolysis of the molten mixture results in the production of molten aluminium at the cathode and carbon dioxide gas at the carbon anode.