Which of the following changes represents an oxidation process?

• A. Fe^{2+} ightarrow Fe^{3+} + e^{-}
• B. O_{2} + 4e^{-} + 4H^{+} ightarrow 2H_{2}O
• C. Cu^{2+} + 2e^{-} ightarrow Cu
• D. Cl_{2} + 2e^{-} ightarrow 2Cl^{-}

Answer: (A)

Verified step by step guidance

1. Recall that oxidation is defined as the loss of electrons by a species, while reduction is the gain of electrons.
2. Examine each given half-reaction to identify whether electrons are being lost or gained:
3. For the reaction \(Fe^{2+} \rightarrow Fe^{3+} + e^{-}\), notice that an electron is produced on the product side, indicating loss of an electron, which corresponds to oxidation.
4. For the other reactions, electrons appear on the reactant side, meaning those species are gaining electrons, which corresponds to reduction.
5. Therefore, the half-reaction where electrons are on the product side represents oxidation.