9701 MCQ Solution 33

Question 33: [Physical > Electrochemistry]:

Which statements about the commercial extraction of aluminium are correct?

1 The cathode reaction is Al³⁺ + 3e^- à Al.

2 The lining of the electrolytic cell acts as the cathode.

3 The electrolyte is purified Al₂O₃ in Na₃AlF₆.

Reference: Past Exam Paper – November 2002 Paper 1 Q33

Solution 33:

Answer: A.

In the extraction of aluminium the electrolyte is molten aluminium oxide. The cathode is negatively charged, attracts the Al³⁺ ions and reduce them to Al atoms, thus 1 is correct. 2 is a fact. 

Na₃AlF₆ commonly known as cryolite is added to the aluminium oxide thus all 3 are correct, thus option A is the correct answer.