Question

Hydrogen peroxide can act as either an oxidizing agent or a reducing agent depending on the species present in solution. Write the balanced half-reaction equations for each situation. Write the balanced half-reaction equation for when H2O2(aq) acts as an oxidizing agent in an acidic solution. Phases are optional.

Answer 1

Reduction: 2 H⁺(aq) + H₂O₂(aq) + 2 e⁻ ⇒ 2 H₂O(l)

Oxidation: H₂O₂(aq) ⇒ O₂(g) + 2 H⁺(aq) + 2 e⁻

Step-by-step explanation:

In H₂O₂, hydrogen has the oxidation number +1 and oxygen the oxidation number -1.

In the reduction half-reaction (H₂O₂ is the oxidizing agent), H₂O₂ forms H₂O. The oxidation number of oxygen decreases from -1 to -2.

2 H⁺(aq) + H₂O₂(aq) + 2 e⁻ ⇒ 2 H₂O(l)

In the oxidation half-reduction (H₂O₂ is the reducing agent), H₂O₂ forms O₂. The oxidation number of oxygen increases from -1 to 0.

H₂O₂(aq) ⇒ O₂(g) + 2 H⁺(aq) + 2 e⁻