6.4 Exercises

Section 6.4 Exercises

1. For the standard cell potentials given here, determine the ΔG° for the cell in kJ at 298.15 K.

   (a) 0.000 V, n = 2

   (b) +0.434 V, n = 2

   (c) −2.439 V, n = 1

2. 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) [latex]\text{Hg}(l)\;+\;\text{S}^{2-}(aq\text{, }0.10\;\text{M})\;+\;2\text{Ag}^{+}(aq\text{, }0.25\;\text{M})\;{\longrightarrow}\;2\text{Ag}(s)\;+\;\text{HgS}(s)[/latex]

   (b) The galvanic cell made from a half-cell consisting of an aluminum electrode in 0.015 M aluminum nitrate solution and a half-cell consisting of a nickel electrode in 0.25 M nickel(II) nitrate solution.

   (c) The cell made of a half-cell in which 0.11 M bromide ion is oxidized to 0.20 M aqueous bromine and a half-cell in which aluminum ion at 0.023 M is reduced to aluminum metal.

3. Use the data on standard reduction potentials (Source: OpenStax Chemistry 2e) to determine the equilibrium constant for the following reactions at 298 K.

   (a) [latex]\text{AgCl}(s)\;{\rightleftharpoons}\;\text{Ag}^{+}(aq)\;+\;\text{Cl}^{-}(aq)[/latex]

   (b) [latex]\text{CdS}(s)\;{\rightleftharpoons}\;\text{Cd}^{2+}(aq)\;+\;\text{S}^{2-}(aq)[/latex]

   (c) [latex]\text{Hg}^{2+}(aq)\;+\;4\text{Br}^{-}(aq)\;{\rightleftharpoons}\;[\text{HgBr}_4]^{2-}(aq)[/latex]

   (d) [latex]\text{H}_2\text{O}(l)\;{\rightleftharpoons}\;\text{H}^{+}(aq)\;+\;\text{OH}^{-}(aq)[/latex]