Question

In the electrolysis of molten aluminium oxide for extraction of aluminium, the following reactions take place:

1. \[\ce{Al^3+ + 3e^- -> Al}\]
2. \[\ce{2O^2- -> O2 + 4e^-}\]
3. \[\ce{C + O2 -> CO2}\]
4. \[\ce{Al2O3 ⇌ 2Al^3+ + 3O^2-}\]

The reaction that takes place at the negative electrode is:

Options

• 1

• 2

• 3

• 4

Answer 1

1

Explanation:

In electrolysis, the negative electrode (cathode) attracts positive ions (cations).

• Al³⁺ is a positive ion, so it moves to the cathode.
• There, it gains 3 electrons (reduction) to become neutral aluminium metal:
  \[\ce{Al^3+ + 3e^- -> Al}\]