Question

Electrolytic reduction of alumina to aluminium by Hall- Heroult process is carried out (a) in the presence of NaCl(b) in the presence of fluorite(c) in the presence of cryolite which forms a melt with lower melting temperature(d) in the presence of cryolite which forms a melt with higher melting temperature

Answer 1

c) in the presence of cryolite which forms a melt with lower melting point

Answer 2

Answer:

(c) in the presence of cryolite which forms a melt with lower melting temperature is the correct answer.

Explanation:

Aluminum has atomic number 13.

Its oxidation state is +3.

Important mknerals of aluminum are

Bauxite

Diaspore

Corundum

Cryolite

Aluminum is usually extracted from bauxite.

It can be done by 3 preocsses

1 Bayer's process

2 Hall's process

3 Serperck's process

In Hall and Herlout's process aluminum is extracted from alumina by the process of electrolysis.

A fused mixture of alumina is taken with cryolite and flurospar in an iron tank.

Cryolite and flurospar are added to make alumina a good conductor of electricity.

It also lowers fusion temperature to 1140K.

It is covered with powdered coke to prevent oxidation and loss of heat due radiation.