Chemistry 2e · 17.4 Potential, Free Energy, and Equilibrium

Potential, Free Energy, and Equilibrium: practice problems

3 problems from the book, with its answers. Check your working, or have any of them explained to you on the whiteboard.

1. Exercises 27

   For each pair of standard cell potential and electron stoichiometry values below, calculate a corresponding standard free energy change (kJ).

   (a) 0.000 V, n = 2

   (b) +0.434 V, n = 2

   (c) −2.439 V, n = 1

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2. Exercises 29

   Determine the standard cell potential and the cell potential under the stated conditions for the electrochemical reactions described here. State whether each is spontaneous or nonspontaneous under each set of conditions at 298.15 K.

   (a) $\text{Hg}(l)+{\text{S}}^{2-}(aq\text{, 0.10}M)+2{\text{Ag}}^{\text{+}}(aq\text{, 0.25}M)⟶2\text{Ag}(s)+\text{HgS}(s)$

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3. Exercises 31

   Use the data in Appendix L to calculate equilibrium constants for the following reactions. Assume 298.15 K if no temperature is given.

   (a) $\text{AgCl}(s)\rightleftharpoons {\text{Ag}}^{\text{+}}(aq)+{\text{Cl}}^{\text{-}}(aq)$

   (b) $\text{CdS}(s)\rightleftharpoons {\text{Cd}}^{2+}(aq)+{\text{S}}^{2-}(aq)\text{at 377 K}$

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