Question

Illustrate oxidising, reducing and acidic properties of hydrogen peroxide with equations.

Answer 1

Hydrogen peroxide can act oxidising agent and reducing agent in both acidic and basic medium.

(a) Oxidising action in acidid medium:

$$2\mathrm{Fe}{\phantom{A}}^{2+}+2\mathrm{H}{\phantom{A}}^{+}+\mathrm{H}{\phantom{A}}_2\mathrm{O}{\phantom{A}}_2⟶2\mathrm{Fe}{\phantom{A}}^{3+}+2\mathrm{H}{\phantom{A}}_2\mathrm{O}$$

(b) Reducing action in acidic medium:

$$2\mathrm{MnO}{\phantom{A}}_4^{-}+6\mathrm{H}{\phantom{A}}^{+}+5\mathrm{H}{\phantom{A}}_2\mathrm{O}{\phantom{A}}_2⟶2\mathrm{Mn}{\phantom{A}}^{2+}+8\mathrm{H}{\phantom{A}}_2\mathrm{O}+5\mathrm{H}{\phantom{A}}_2$$

$$\mathrm{HOCl}+\mathrm{H}{\phantom{A}}_2\mathrm{O}{\phantom{A}}_2⟶\mathrm{H}{\phantom{A}}_3\mathrm{O}{\phantom{A}}^{-}+\mathrm{Cl}{\phantom{A}}^{-}+\mathrm{O}{\phantom{A}}_2$$

(c) Oxidising action in basic medium:

$$2\mathrm{Fe}{\phantom{A}}^{2+}+\mathrm{H}{\phantom{A}}_2\mathrm{O}{\phantom{A}}_2⟶2\mathrm{Fe}{\phantom{A}}^{3+}+2\mathrm{OH}{\phantom{A}}^{-}$$

$$\mathrm{Mn}{\phantom{A}}^{2-}+\mathrm{H}{\phantom{A}}_2\mathrm{O}{\phantom{A}}_2⟶\mathrm{Mn}{\phantom{A}}^{4-}+2\mathrm{OH}{\phantom{A}}^{-}$$

(d) Reduction action in basic medium:

$$\mathrm{I}{\phantom{A}}_2+\mathrm{H}{\phantom{A}}_2\mathrm{O}{\phantom{A}}_2+2\mathrm{OH}{\phantom{A}}^{-}⟶2\mathrm{I}{\phantom{A}}^{-}+2\mathrm{H}{\phantom{A}}_2\mathrm{O}+\mathrm{O}{\phantom{A}}_2$$

$$2\mathrm{MnO}{\phantom{A}}_4^{-}+3\mathrm{H}{\phantom{A}}_2\mathrm{O}{\phantom{A}}_2⟶2\mathrm{MnO}{\phantom{A}}_2+3\mathrm{O}{\phantom{A}}_2+2\mathrm{H}{\phantom{A}}_2\mathrm{O}+2\mathrm{OH}{\phantom{A}}^{-}$$