Question
The electrochemical extraction of aluminium from bauxite ore involves
JEE Advanced
Chemistry
General Principles and Processes of Isolation of Metals
2022
JEE Advanced 2022 (Paper 1)
JEE Advanced Chemistry Question (2022) — Solution
Options
- A. the reaction of Al 2 O 3 with coke C at a temperature > 2500 ° C .
- B. the neutralization of aluminate solution by passing CO 2 gas to precipitate hydrated alumina Al 2 O 3 . 3 H 2 O .
- C. the dissolution of Al 2 O 3 in hot aqueous NaOH .
- D. the electrolysis of Al 2 O 3 mixed with Na 3 AlF 6 to give Al and CO 2 .
Answer
D. the electrolysis of Al 2 O 3 mixed with Na 3 AlF 6 to give Al and CO 2 .
Step-by-step solution
(A) The reduction of Al 2 O 3 with coke C at a temperature > 2500   ° C is not carried out due to the formation of carbides. (B) It is correct as neutralisation of aluminate solution is done by passing CO 2 gas to precipitate hydrated alumina. (C) Reaction of powdered one is carried out with hot concentrated NaOH at 473   K - 523   K and 35 - 36 bar pressure. (D)Aluminium In the metallurgy of aluminium, purified Al 2 O 3 is mixed with Na 3 AlF 6 or CaF 2 which lowers the melting point of the mixture and brings conductivity.Thus electrolysis of the molten mass is carried out in an electrolytic cell using carbon electrodes. The oxygen liberated at anode reacts with the carbon of anode producing CO and CO 2 and Al at the cathode.
Related: Chemistry — General Principles and Processes of Isolation of Metals · All PYQ Banks