Ncert Exercises & Solutions

9.25 Write chemical reactions to justify that hydrogen peroxide can function as an oxidising as well as reducing agent.

Hydrogen peroxide,

H_{2} O_{2}

acts as an oxidizing as well as a reducing agent in both acidic and alkaline media.

Reactions involving oxidizing actions are:

$1) 2 F e^{2 +} + 2 H^{+} + H_{2} O_{2} \to 2 F e^{3 +} + 2 H_{2} O$
$2) M n^{2 +} + H_{2} O_{2} \to M n^{4 +} + 2 O H^{-}$
$3) P b S + 4 H_{2} O_{2} \to P b S O_{4} + 4 H_{2} O$
$4) 2 F e^{2 +} + H_{2} O_{2} \to 2 F e^{3 +} + 2 O H^{-}$

Reactions involving reductions are;

$1) 2 M n {O^{-}}_{4} + 6 H^{+} + 5 H_{2} O_{2} \to 2 M n^{2 +} + 8 H_{2} O + 5 O_{2}$
$2) I_{2} + H_{2} O_{2} + 2 O H^{-} \to 2 I^{-} + 2 H_{2} O + O_{2}$
$3) H O C I + H_{2} O_{2} \to H_{3} O^{+} + C l^{-} + O_{2}$
$4) 2 M n {O^{-}}_{4} + 3 H_{2} O_{2} \to 2 M n O_{2} + 3 O_{2} + 2 H_{2} O + 2 O H^{-}$