QJEEAdv22Chd671: JEE Advanced 2022 Chemistry - Class 12 JEEAdv22Chd671 Solution: The electrochemical extraction of aluminum from bauxite ore…

Question

Verified Solution • 2025–26 Session moderate

The electrochemical extraction of aluminum from bauxite ore involves

A the reaction of $\mathrm{Al}_{2} \mathrm{O}_{3}$ with coke $(\mathrm{C})$ at a temperature $>2500^{\circ} \mathrm{C}$ .
B the neutralization of aluminate solution by passing $\mathrm{CO}_{2}$ gas to precipitate hydrated alumina $\left(\mathrm{Al}_{2} \mathrm{O}_{3} \cdot 3 \mathrm{H}_{2} \mathrm{O}\right)$ .
C the dissolution of $\mathrm{Al}_{2} \mathrm{O}_{3}$ in hot aqueous $\mathrm{NaOH}$ .
D the electrolysis of $\mathrm{Al}_{2} \mathrm{O}_{3}$ mixed with $\mathrm{Na}_{3} \mathrm{AlF}_{6}$ to give $\mathrm{Al}$ and $\mathrm{CO}_{2}$ .

Accepted Answer

(A) The reduction of Al₂O₃ with coke (C) at a temperature > 2500 $^\circ$ C is not carried out due to the formation of carbides.

(B) It is correct as neutralisation of aluminate solution is done by passing CO₂ 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) Electrolysis of Al₂O₃ is done mixed with Na₃AlF₆ to produce Al and CO₂. It is a correct statement.

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