Use the following reaction to answer the question:

Question

2Al + 3Fe³⁺ → 2Al³⁺ + 3Fe
Which of the following is the correct oxidation half-reaction?

A. Al³⁺ + 3e⁻ → Al
B. Fe³⁺ + 3e⁻ → Fe
C. Al → Al³⁺ + 3e
D. Fe → Fe³⁺ + 3e⁻

Answer 1

To determine the correct oxidation half-reaction for the given reaction, we need to identify which substance is being oxidized. An oxidation half-reaction will show the loss of electrons.

In the given reaction:

\[ 2 \text{Al} + 3 \text{Fe}^{3+} \rightarrow 2 \text{Al}^{3+} + 3 \text{Fe} \]

• Aluminum (Al) is being oxidized to aluminum ions (Al³⁺), which means it loses electrons.
• The oxidation of aluminum can be represented as:

\[ \text{Al} \rightarrow \text{Al}^{3+} + 3\text{e}^- \]

This correctly depicts that aluminum is being oxidized and is the half-reaction we are looking for.

Now, looking at the options provided:

A. \( \text{Al}^{3+} + 3e^- \rightarrow \text{Al} \) (This is a reduction reaction.) B. \( \text{Fe}^{3+} + 3e^- \rightarrow \text{Fe} \) (This is also a reduction reaction.) C. \( \text{Al} \rightarrow \text{Al}^{3+} + 3e \) (This represents oxidation correctly.) D. \( \text{Fe} \rightarrow \text{Fe}^{3+} + 3e^- \) (This is oxidation for iron, but not for aluminum.)

Thus, the correct oxidation half-reaction is C. \( \text{Al} \rightarrow \text{Al}^{3+} + 3e \).