1. Permanganate and hydrogen peroxide

2. Hydrogen peroxide solution is colourless. Permanganate in neutral conditions

3. When potassium permanganate solution is added, the purple solution turns brown.

4. If you look closely, you can see bubbles of a colourless gas being formed.

5. Leave the beaker to settle for 10 minutes and a brown solid is clearly visible.

6. Neutral permanganate is reduced to MnO 2 (s): MnO 4 - + 4H + + 3e - → MnO 2 (s) + 2H 2 O purple brown H 2 O 2 → O 2 (g) + 2H + + 2e - 2MnO 4 - + 2H + + 3H 2 O 2 → 2MnO 2 + 4H 2 O + 3O 2

7. Fresh hydrogen peroxide solution is acidified with sulfuric acid. We don’t use HCl because the Cl - ion can act as a reducing agent. Permanganate in acid conditions

8. Purple permanganate solution turns colourless as it is added to the acidified peroxide.

9. Oxygen gas is again produced, but is not visible in this very dilute solution. MnO 4 - + 8H + + 5e - → Mn 2+ + 4H 2 O H 2 O 2 → O 2 + 2H + + 2e - 5H 2 O 2 + 2MnO 4 - + 6H + → 5O 2 + 2Mn 2+ + 8H 2 O