Question

The sketch illustrates refining of aluminium by Hoope's process.

The electrolyte in the tank is ______________.

• A. aluminum
• B. iron
• C. lead
• D. none of these

Answer 1

The correct option is A aluminum

In Hoope's process, electrolytic cell is made of iron, which is lined with carbon at the bottom. It contains three layers of fused mass. The lower layer consists of an alloy of impure aluminum with copper. This layer serves as anode. The middle layer consists of a solution of cryolite (Na₃AlF₆) and barium fluoride. The upper layer consists of pure aluminum and serves as cathode.

During electrolysis $A{l}^{3+}$ ions from the middle layer migrate to the upper layer where they are reduced to aluminum by gainingthree electrons. Equal numbers of $A{l}^{3+}$ ions are produced in the lower layer. As the Aluminium ions are getting reduced and oxidised $Al$ is working as electrolyte.