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