Question

What is the reduction half-reaction for Mg(s) + ZnCl2(aq) MgCl2(aq) + Zn(s)?

A. Zn2+ + 2e- Zn(s)
B. Mg(s) Mg2+ + 2e-
C. Mg2+ + 2e- Mg(s)
D. Zn(s) Zn2+ + 2e-

Answer 1

a. zn2 + 2e- --zn(s)
zinc oxide is reduced therefore it's an oxidizing agent

Answer 2

Reduction half:
`Zn2+(aq )+ 2e- \rightarrow Zn(s)`

Step-by-step explanation:

Redox reactions are reduction-oxidation reactions in which there is an exchange of electrons between the reactants.

The species which loses electrons is said to have undergone oxidation, whereas the system that gains electrons is known to have undergone reduction. Therefore, a redox reaction can be represented in terms of half-reactions i.e. the reduction half and the oxidation half.

The given reaction is:

`Mg(s)+ZnCl2(aq)\rightarrow MgCl2(aq)+ Zn(s)`

Here the oxidation state of Mg changes from 0 to +2 i.e. it loses 2 electrons and undergoes oxidation

In contrast, the oxidation state of Zn changes from +2 to 0, it gains 2 electrons and undergoes reduction

The half reactions are:

Reduction:

`Zn2+(aq )+ 2e- \rightarrow Zn(s)`

Oxidation:

`Mg(s)\rightarrow Mg2+(aq) + 2e-`