Question

The following is a sketch of an electrolytic cell used in the extraction of aluminium :

(a) What is the substance of which the electrode A and B are made?
(b) At which electrode (A or B) is aluminium formed?
(c) What are the two aluminium compounds in the electrolyte C?
(d) Why is it necessary for electrode B to be continuously replaced?

Answer 1

(i) A is made of carbon and B is a thick graphite rod.

A → Cathode

B → Anode

(ii) Aluminium is formed at electrode A.

(iii) The two aluminium compound in the electrolyte C is Na₃AlF₆, Al₂O₃.

(iv) It is necessary to continuously replace electrode B from time to time as it gets oxidized by the oxygen evolved.