# Decomposition of potassium permanganate under prolonged heating

When we heat potassium permanganate, the equation of the decomposition of it is: $$\ce{2KMnO4 ->[\Delta] K2MnO4 + MnO2 + O2}$$

So what will happen to potassium manganate ($\ce{K2MnO4}$) when we continue heating?

• There are numerous mixed oxide of Mn, so I believe structures like $\ce{KMnO2}$ will be formed. – permeakra Mar 10 '14 at 14:27

## 2 Answers

Potassium manganate is produced by reacting manganese dioxide with potassium hydroxide and oxygen gas :

$\ce{2 MnO2 + 4 KOH + O2 → 2 K2MnO4 + 2 H2O}$

So I would suspect that the reverse process will occur when further heating. (Of course when there is no water available you might get other products, maybe potassium oxide instead of potassium hydroxide)

The reaction is given here.

$$\ce{3K2MnO4 ->[\Delta] 2K3MnO4 + MnO2 + O2}$$

The thermal decomposition of potassium manganate to produce potassium hypomanganate, manganese(IV) oxide and oxygen. This reaction takes place at a temperature of 190-500°C.