Question

Which of the following is a reduction half-reaction?

a) 2H^+ + 2e^– → H

b) Na → Na^+ + e^–

c) NO + 2H2O → N3^– + 4H^+ + 3e^–

d) Zn → Zn^2+ + 2e^–

Answer 1

Step-by-step explanation:

2H⁺ + 2e⁻ ⇄ 2H

This is a reduction half which occurs at the cathode electrode. As typical with redox reactions in which reduction takes place, we have:

1. Decrease in oxidation number

2. Gain of electrons

There is a gain of two electrons and the hydrogen ion is reduced to a hydrogen atom at the cathode.

In an oxidation half, the opposite happens. We would have a loss of electrons and increase in oxidation number.