Question

Explain acidified KMnO₄ is a powerful oxidising agent with 5 examples.

Answer 1

1. In the presence of dilute sulphuric acid, potassium permanganate acts as a very strong oxidising agent. Permanganate ions is converted into Mn⁺ ion. 

MnO₄^- + 8H⁺ +5e^- → Mn²⁺ + 4H₂O 

Example: 1. Potassium permanganate oxidises ferrous salts to ferric salts.

2. Potassium permanganate oxidises iodide ions to iodine. 

2MnO₄^-  + 10I^-+ 16H⁺ → 2Mn²⁺ + 5I₂ + 8H₂O 

3. Potassium permanganate oxidises sulphide ion to sulphur. 

2MnO₄^-  + 5S^_2- + 16H⁺ → 2Mn²⁺ + 5S + 8H₂O 

4. Potassium permanganate oxidises oxalic acid to CO₂.

2MnO₄^-  +  5(COO)^2- + 16H⁺ → 2Mn²⁺ + 10CO₂ + 10H₂O 

5. Potassium permanganate oxidises alcohols to aldehyde.

2KMnO₄ + 3H₂SO₄ + 5CH₃CH₂OH → 2K₂SO₄ + 2MnSO₄ + 5CH₃CHO + 8H₂O