UPSC Combined Geo-Scientist, Mains · 2021 · Mains Paper II
Q10(a). E° of Fe²⁺/Fe from two other couples
Question
From the following reduction reactions and E° values: Fe³⁺(aq) + e⁻ → Fe²⁺(aq), E°₁ = 0.772 V; Fe³⁺(aq) + 3e⁻ → Fe(s), E°₂ = −0.036 V. Calculate E°₃ for the half-cell reaction Fe²⁺(aq) + 2e⁻ → Fe(s).
Answer in brief
E°₃ = −0.440 V (ΔG°₃ = +84.9 kJ mol⁻¹).
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Coversstandard electrode potentialLatimer diagramcombining half-reactionsΔG = −nFEFrost diagram
All parts of Question 10
- 10(a) E° of Fe²⁺/Fe from two other couples5 marks
- 10(b) Molecular diameter of helium from the van der Waals b5 marks