Question

1. What is the effect of heat on KMnO₄ 

2. Give any two examples to show the oxidising property of KMnO₄.

Answer 1

(1). On heating, KMnO₄ decomposes at 513 K into potassium manganate and oxygen gas is evolved.

2KMnO₄ \(\overset{Heat}\longrightarrow\)  K₂MnO₄ + MnO₂ + O₂

(2). Two examples to show the oxidising property of KMnO₄

In acid medium it oxidises iodide to iodine.

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

In neutral or faintly alkaline solutions it oxidises iodide to iodate.

2MnO₄^- + H₂O + I^- → 2MnO₂ + 2OH^- + IO₃^-