How does the acidified KMnO₄ react with the following:
(a) Iron(II) solution, (b)SO₃^2–, (c) Iodide (I^–) ion, (d) oxalic acid, (e) NO₂^– (Nitrite ion).

a) Fe2+ ion (green) is converted to Fe3+ (yellow):

5Fe2+ + MnO₄^– + 8H⁺ ——> Mn²⁺ + 4H₂O + 5Fe³⁺

b) Sulphurous acid or sulphite is oxidised to a sulphate or sulphuric acid:

5SO₃^2– + 2MnO₄^– + 6H⁺ ——> 2Mn²⁺ + 3H₂O + 5SO₄^2–


c) Iodine is liberated from potassium iodide :

10I^– + 2MnO₄^– + 16H⁺ ——> 2Mn²⁺ + 8H₂O + 5I₂


d) Oxalate ion or oxalic acid is oxidised at 333 K:

5C₂O₄^2– + 2MnO₄^– + 16H⁺ ——> 2Mn²⁺ + 8H₂O + 10CO₂


e) Nitrite is oxidised to nitrate:

5NO₂^– + 2MnO₄^– + 6H⁺ ——> 2Mn²⁺ + 5NO₃^– + 3H₂O