alleryWhich half-reaction from the notes represents reduction?
- $Zn \rightarrow Zn^{2+} + 2e^{-}$
- $Cu^{2+} + 2e^{-} \rightarrow Cu$
- $Cu \rightarrow Cu^{2+} + 2e^{-}$
- $Zn^{2+} \rightarrow Zn + 2e^{-}$
Show answer and solution
Correct answer: B. $Cu^{2+} + 2e^{-} \rightarrow Cu$
Reduction involves gain of electrons, so electrons must appear on the reactant side.
In $Cu^{2+} + 2e^{-} \rightarrow Cu$, copper ions gain electrons to form copper metal.