INFORMATION:
We have the next balanced ionic equation:
2Al(s) + 3Cu²⁺(aq) → 2Al³⁺(aq) + 3Cu(s)
And we must determine the half-reaction that represents the reduction that occurs
STEP BY STEP EXPLANATION:
To determine it we must use the given information about the ionic charge of atoms given in the formula
We can see that there is a reduction in the formula since we initially have 3Cu²⁺ and then we obtain 3Cu
Since the initial ionic charge for Cu is 2+, we need to add 2e¯ to obtain Cu. Then, the reduction half-reaction would be Cu²⁺ + 2e¯ → Cu
ANSWER:
(4) Cu²⁺ + 2e¯ → Cu
