Consider the reaction: Zn + Cu^{2+} → Zn^{2+} + Cu. What is being reduced in this reaction?

• A. Zn^{2+}
• B. Cu
• C. Zn
• D. Cu^{2+}

Answer: (D)

Verified step by step guidance

1. Identify the oxidation states of the species involved in the reaction: Zn (elemental zinc), Cu^{2+} (copper ion with a +2 charge), Zn^{2+} (zinc ion with a +2 charge), and Cu (elemental copper).
2. Recall that reduction is the gain of electrons, which corresponds to a decrease in oxidation state, while oxidation is the loss of electrons, corresponding to an increase in oxidation state.
3. Compare the oxidation states of each species before and after the reaction: Zn goes from 0 to +2 (oxidized), Cu^{2+} goes from +2 to 0 (reduced).
4. Determine which species is reduced by identifying the one whose oxidation state decreases; in this case, Cu^{2+} gains electrons and is reduced to Cu.
5. Conclude that Cu^{2+} is the species being reduced in the reaction.