Q.Hydrogen peroxide can function as an oxidising agent as well as reducing agent. Substantiate this statement with suitable examples.

Step 1. Hydrogen peroxide's oxygen sits at the intermediate -1 oxidation state, between O₂ (0) and water/oxide (-2) -- which is exactly why it can move either way, acting as an oxidant (its O going from -1 down to -2) or a reductant (its O going from -1 up to 0).

Step 2. As an oxidising agent (acidic medium): $H_2O_2 + 2H^+ + 2e^- \rightarrow 2H_2O$ ($E^0 = +1.77$ V). Example -- H₂O₂ oxidises Fe²⁺ to Fe³⁺: $2FeSO_4 + H_2SO_4 + H_2O_2 \rightarrow Fe_2(SO_4)_3 + 2H_2O$.

Step 3. As a reducing agent (basic medium): $HO_2^- + OH^- \rightarrow O_2 + H_2O + 2e^-$ ($E^0 = +0.08$ V). Example -- H₂O₂ reduces (decolourises) acidified potassium permanganate: $2KMnO_4 + 3H_2O_2 \rightarrow 2MnO_2 + 2KOH + 2H_2O + 3O_2$. …

Give one worked example of H2O2 oxidising something (Fe2+ to Fe3+) and one of it being oxidised/reducing something else (d …

• Giving only the decomposition reaction (H2O2 -> H2O + 1/2 O2) as 'proof' -- that is disproportionation (H2O2 acting as both oxidant and reductant on itself), not the same as sho …