KMnO₄ decomposes on heating at 513 K to form O₂ along with

Solution

Chemistry ma’am · 3 steps

Heat splits the Mn(+7) two ways: part drops to +6 in manganate, part to +4 in MnO₂, and oxygen escapes.

1. Who loses electrons. In KMnO₄, Mn is already at +7, its highest state, so it cannot be oxidised further. On heating, oxide oxygen (−2) is oxidised to O₂ (0), so manganese must be reduced to take those electrons.

   2KMnO₄ →(Δ, 513 K) K₂MnO₄ + MnO₂ + O₂

2. Check electrons. The two O atoms that form O₂ lose 4 electrons. One Mn goes from +7 to +6 (gains 1) and the other from +7 to +4 (gains 3), which is also 4. Atoms balance too: 2 K, 2 Mn and 8 O on each side.
3. So. Along with O₂, the products are potassium manganate K₂MnO₄ and manganese dioxide MnO₂, which is option (c).

The idea to keep. Heated KMnO₄ gives green K₂MnO₄, black MnO₂ and O₂. Mn is reduced only partway, to +6 and +4, never to the metal.

Answer from the NTA final answer key. Solution by PrepWiser.