Q. The standard electrode potential (E°) for the half-cell reaction Fe³⁺ + e⁻ → Fe²⁺ at 298 K is (Given : E°(Fe³⁺/Fe) = −0.04 V and E°(Fe²⁺/Fe) = −0.44 V at 298 K)
A) +0.92 V
B) +0.40 V
C) +0.76 V
D) −0.48 V
Explanation
[Solution from source] Potentials are not additive but ΔG° values are. Fe³⁺ + 3e⁻ → Fe: ΔG° = +0.12F. Fe²⁺ + 2e⁻ → Fe: ΔG° = +0.88F. Subtracting, Fe³⁺ + e⁻ → Fe²⁺ has ΔG° = −0.76F, so E° = +0.76 V. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.