For the cell Cd |CdCl₂ | AgCl | Ag; Ecell o=0.675 V and dEcell o / dT=-6.5 × 10⁻⁴ VK⁻¹ at 27° C. The Δ H (kJ mol⁻¹) value for the reaction Cd+2 AgCl → 2 Ag+CdCl₂ is closest to

Q31 · CSIR-NET Chemistry, June 2021

Paper: CSIR-NET June 2021 · Subject: Physical Chemistry · Chapter: Electrochemistry · Topic: Electrochemistry – General · Marks: 2 · Difficulty: Medium

For the cell $\mathrm{Cd}\left|\mathrm{CdCl}_{2} \| \mathrm{AgCl}\right| \mathrm{Ag} ; \mathrm{E}_{\text {cell }}^{\mathrm{o}}=0.675 \mathrm{V}$ and $\mathrm{dE}_{\text {cell }}^{\mathrm{o}} / \mathrm{dT}=-6.5 \times 10^{-4} \mathrm{VK}^{-1}$ at $27^{\circ} \mathrm{C}$. The $\Delta \mathrm{H}\left(\mathrm{kJ} \mathrm{mol}^{-1}\right)$ value for the reaction $\mathrm{Cd}+2 \mathrm{AgCl} \rightarrow 2 \mathrm{Ag}+\mathrm{CdCl}_{2}$ is closest to

(a)-168

(b)-123

(c)-95

(d)-234

Answer

Answer: A ✓ checked by 4AB · confidence high

Explanation

ΔH = −nF[E° − T(dE°/dT)] = −2 × 96485 × (0.675 + 300 × 6.5×10⁻⁴) ≈ −168 kJ mol⁻¹ (a).

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