Given the balanced ionic equation:
zn(s) + cu2+(aq) → zn2+(aq) + cu(s)
which equation represents the oxidation half reaction?
(1) zn(s) + 2e– → zn2+(aq)
(2) zn(s) → zn2+(aq) + 2e–
(3) cu2+(aq) → cu(s) + 2e–
(4) cu2+(aq) + 2e– → cu(s)

Option (2) is the correct answer.

Explanation:

Oxidation is the process in which there is loss of electrons or increase in oxidation number of the element.

Whereas reduction is the process in which there is gain of electrons or decrease in oxidation number of the element.

For example,

Oxidation-half reaction:

Reduction-half reaction:

Thus, we can conclude that the given equation Zn(s) → Zn2+(aq) + 2e– represents the oxidation half reaction.