The standard cell potential of cell, Pt | H₂(g) | HBr(aq) | AgBr(s) | Ag(s), was measured over a range of temperatures, and the data was fitted as E⁰(Volt)=0.01-1×10⁻⁴(T-298)-2×10⁻⁶(T-298)² The standard reaction entropy (J K⁻¹ mol⁻¹) and enthalpy (kJ mol⁻¹) at 298 K are

Q15 · CSIR-NET Chemistry, June 2017

Paper: CSIR-NET June 2017 · Subject: Physical Chemistry · Chapter: Electrochemistry · Topic: Electrochemistry – General · Marks: 2 · Difficulty: Medium

The standard cell potential of cell, $\mathrm{Pt\,|\,H_2(g)\,|\,HBr(aq)\,|\,AgBr(s)\,|\,Ag(s)}$, was measured over a range of temperatures, and the data was fitted as $E^{0}(\mathrm{Volt})=0.01-1\times10^{-4}(T-298)-2\times10^{-6}(T-298)^{2}$ The standard reaction entropy ($\mathrm{J\,K^{-1}\,mol^{-1}}$) and enthalpy ($\mathrm{kJ\,mol^{-1}}$) at $298\,K$ are

(a)-9.65 and -3.84

(b)-3.84 and -9.65

(c)-18.3 and-7.68

(d)-7.68 and -18.3

Answer

Answer: A ✓ checked by 4AB · confidence high

Explanation

At 298 K, dE°/dT = −1×10⁻⁴ V K⁻¹ and E° = 0.01 V, n = 1. ΔS° = nF(dE°/dT) = 96485 × (−1×10⁻⁴) = −9.65 J K⁻¹ mol⁻¹. ΔH° = −nFE° + TΔS° = −964.9 − 2875.7 J = −3.84 kJ mol⁻¹.

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