Paper: CSIR-NET June 2017 · Subject: Physical Chemistry · Chapter: Electrochemistry · Topic: Electrochemistry – General · Marks: 2 · Difficulty: Medium
The standard cell potential of cell, $\mathrm{Pt}\left|\mathrm{H}_{2}(\mathrm{g})\right| \mathrm{HBr}(\mathrm{aq})|\mathrm{AgBr}(\mathrm{s})| \mathrm{Ag}(\mathrm{s})$, was measured over a range of temperatures, and the data was fitted as $\mathrm{E}_{0}($ Volt $)=0.01-1 \times 10^{-4}(\mathrm{T}-298)-2 \times 10^{-6}(\mathrm{T}-298)^{2}$. The standard reaction entropy ( $\mathrm{JK}^{-1} \mathrm{mol}^{-1}$ ) and enthalpy ( $\mathrm{kJmol}^{-1}$ ) 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
dE°/dT at 298 K = −1×10⁻⁴ V K⁻¹; ΔS° = nF(dE°/dT) = −9.65 J K⁻¹ mol⁻¹; ΔH° = −nFE° + TΔS° = −965 − 2876 J = −3.84 kJ mol⁻¹.