Which half-reaction from the notes is an example of reduction?
- $Zn \rightarrow Zn^{2+} + 2e^-$
- $Cu \rightarrow Cu^{2+} + 2e^-$
- $Cu^{2+} + 2e^- \rightarrow Cu$
- $Zn^{2+} \rightarrow Zn + 2e^-$
Show answer and solution
Correct answer: C. $Cu^{2+} + 2e^- \rightarrow Cu$
Reduction involves gain of electrons.
In $Cu^{2+} + 2e^- \rightarrow Cu$, copper ions gain electrons to form copper metal, so this is the reduction half-reaction.