Question

Some information regarding a particular compound is given below. A deep purple black crystal which is moderately soluble in water at room temperature and it is prepared from pyrolusite.

1. Identify the compound.

2. Give the chemical reactions involved in the preparation of this compound. 

3. Upon heating to 746 K, what happens to this compound? Give the equation.

Answer 1

1. KMnO₄

2. 2MnO₂ + 4KOH + O₂ → 2K₂MnO₄ + 2H₂O 3MnO₄^2- + 4H⁺ → 2MnO₄ + MnO₂ + 2H₂O

3. Potassium permanganate on strong heating gives potassium manganate, manganese dioxide and oxygen.

2KMnO₄ → K₂MnO₄ + MnO₂ + O₂