Question

On the basis of the following $E^0 $ values, the strongest oxidising agent is $[Fe(CN)_6]^{4-} \rightarrow [Fe(CN)_6]^{3-}+e^-; $ $\hspace15mm E^0=-0.35 V $ $Fe^{2+} \rightarrow Fe^{3+} + e^-;E^0=-0.77 V $

• A. $[Fe(CN)_6]^{4-}$
• B. $Fe^{2+} $
• C. $Fe^{3+} $
• D. $[Fe(CN)_6]^{3-} $

Answer 1

The Correct Option is C

To determine the strongest oxidizing agent, we need to understand the standard reduction potential values E^0 provided for the given half-reactions. The oxidizing agent is a species that gets reduced, which means it gains electrons in a chemical reaction.

The provided reduction potentials are:

• [Fe(CN)_6]^{4-} \rightarrow [Fe(CN)_6]^{3-} + e^-; \, E^0 = -0.35 \, V
• Fe^{2+} \rightarrow Fe^{3+} + e^-; \, E^0 = -0.77 \, V

In terms of reduction potential, a more positive (or less negative) E^0 value indicates a stronger tendency to gain electrons, which means a stronger oxidizing capability.

1. Compare the E^0 values:
   • The reaction [Fe(CN)_6]^{4-} \rightarrow [Fe(CN)_6]^{3-} has an E^0 of -0.35\, V.
   • The reaction Fe^{2+} \rightarrow Fe^{3+} has an E^0 of -0.77\, V.
2. Since -0.35\, V is less negative than -0.77\, V, the species [Fe(CN)_6]^{3-} in the reduction of [Fe(CN)_6]^{4-} has a stronger tendency to gain electrons compared to Fe^{3+} in the reduction of Fe^{2+} reaction.
3. However, the question asks for the "strongest oxidizing agent," which is the species that is on the reduction side and can act as an oxidizing agent. That species will be Fe^{3+} because oxidizing agents are substances that are reduced and cause the oxidation of another substance.

Therefore, the strongest oxidizing agent is Fe^{3+}.