Question

Based on the data given below: \[ E^\circ_{\text{Cr}_2\text{O}_7^{2-}/\text{Cr}^{3+}} = 1.33 \, \text{V}, \quad E^\circ_{\text{Cl}_2/\text{Cl}^-} = 1.36 \, \text{V}, \quad E^\circ_{\text{MnO}_4^-/\text{Mn}^{2+}} = 1.51 \, \text{V}, \quad E^\circ_{\text{Cr}^{3+}/\text{Cr}} = -0.74 \, \text{V}. \] The strongest reducing agent is:

• A. \( \text{Mn}^{2+} \)
• B. \( \text{MnO}_4^- \)
• C. \( \text{Cr} \)
• D. \( \text{Cl}^- \)

Hint:

Remember that the strongest reducing agent is the species with the most negative standard reduction potential, while the strongest oxidizing agent has the most positive potential.

Answer 1

The Correct Option is A

The strongest reducing agent corresponds to the species with the most negative \( E^\circ \) value, as the more negative the value, the greater the tendency to lose electrons.

- \( E^\circ_{\text{Mn}^{2+}/\text{MnO}_4^-} = 1.51 \, \text{V} \) (MnO4^- is a good oxidizing agent).
- \( E^\circ_{\text{Cr}^{3+}/\text{Cr}} = -0.74 \, \text{V} \) (Cr is a reducing agent).

Thus, \( \text{Mn}^{2+} \) has the most negative \( E^\circ \) and is the strongest reducing agent.

Final Answer: \( \text{Mn}^{2+} \).