Ncert Exercises & Solutions

Which of the following equations depict the oxidising nature of $H_{2} O_{2}$ ?

1. $2 {MnO}_{4}^{-} + 6 H^{+} + 5 H_{2} O_{2} \to 2 {Mn}^{2 +} + 8 H_{2} O + 5 O_{2}$

2. $2 {Fe}^{3 +} + 2 H^{+} + H_{2} O_{2} \to 2 {Fe}^{2 +} + 2 H_{2} O + O_{2}$

3. $2 I^{-} + 2 H^{+} + H_{2} O_{2} \to I_{2} + 2 H_{2} O$

4. ${KIO}_{4} + H_{2} O_{2} \to {KIO}_{3} + H_{2} O + O_{2}$

Hint: Oxidising agent itself undergo reduction

Step 1:

In first reaction, Mn oxidation state change from +7 to +2. So reduction occurs and $H_{2} O_{2}$ acts as a reducing agent.

In second reaction, Fe oxidation state change from +3 to +2. So reduction occur and $H_{2} O_{2}$ acts as a reducing agent.

In third reaction, I oxidation state change from -1 to 0. So oxidation occur and $H_{2} O_{2}$ acts as a oxidisng agent.

In fourth reaction, I oxidation state change from +7 to +5. So reduction occur and $H_{2} O_{2}$ acts as a reducing agent.

Step 2:

In third option, $H_{2} O_{2}$ acts as a oxidisng agent.