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

ICSE Class 10 Chemistry PYQ · 2026 Paper · Section A

1(xv)1 Mark · 2026 · Section A · 2026 Paper

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

  1. Al3+ + 3e- ⟶ Al
  2. 2O2- ⟶ O2 + 4e-
  3. C + O2 ⟶ CO2
  4. Al2O3 ⇌ 2Al3+ + 3O2-

The reaction that takes place at the negative electrode is:

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1

Reason — The negative electrode is the cathode where reduction takes place. At the cathode, the positively charged Al3+ ions get attracted, gain 3 electrons, and get deposited as aluminium metal.

Al3+ + 3e- ⟶ Al

Reaction (2) takes place at the anode (oxidation), reaction (3) is the reaction of carbon anode with oxygen, and reaction (4) is the dissociation of alumina.

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