Lawrie Ryan and Roger Norris Solutions for Chapter: Electrochemistry, Exercise 16: Questions

Suggest a suitable reagent from the given data that can carry out the reduction of ${\mathrm{Zn}}^{2+}$ ions to $\mathrm{Zn}$.

$$\begin{gathered} {\mathrm{Zn}}^{2+}+2{\mathrm{e}}^{-}\rightleftharpoons \mathrm{Zn} {\mathrm{E}}^{⊝}=-0.76 \mathrm{V} \\ {\mathrm{Br}}_2+2{\mathrm{e}}^{-}\rightleftharpoons 2{\mathrm{Br}}^{-} {\mathrm{E}}^{⊝}=+1.07 \mathrm{V} \\ {\mathrm{Cr}}^{2+}+2{\mathrm{e}}^{-}\rightleftharpoons \mathrm{Cr} {\mathrm{E}}^{⊝}=-0.91 \mathrm{V} \\ {\mathrm{Fe}}^{3+}+3{\mathrm{e}}^{-}\rightleftharpoons \mathrm{Fe} {\mathrm{E}}^{⊝}=-0.04 \mathrm{V} \end{gathered}$$

Suggest a suitable reagent from the given data that can carry out the oxidation of ${\mathrm{Br}}^{-}$ ions to ${\mathrm{Br}}_2$.

$$\begin{gathered} {\mathrm{Br}}_2+2{\mathrm{e}}^{-}\rightleftharpoons 2{\mathrm{Br}}^{-} {\mathrm{E}}^{⊝}=+1.07 \mathrm{V} \\ {\mathrm{Cr}}^{2+}+2{\mathrm{e}}^{-}\rightleftharpoons \mathrm{Cr} {\mathrm{E}}^{⊝}=-0.91 \mathrm{V} \\ {\mathrm{Fe}}^{3+}+3{\mathrm{e}}^{-}\rightleftharpoons \mathrm{Fe} {\mathrm{E}}^{⊝}=-0.04 \mathrm{V} \\ {\mathrm{Cl}}_2+2{\mathrm{e}}^{-}\rightleftharpoons 2{\mathrm{Cl}}^{-} {\mathrm{E}}^{⊝}=+1.36 \mathrm{V} \end{gathered}$$

Suggest a suitable reagent from the given data that can carry out the reduction of acidified ${\mathrm{SO}}_4^{2-}$ ions to ${\mathrm{SO}}_2$.

$$\begin{gathered} {\mathrm{SO}}_4^{2-}+2{\mathrm{e}}^{-}\rightleftharpoons {\mathrm{SO}}_2 {\mathrm{E}}^{⊝}=+0.17 \mathrm{V} \\ {\mathrm{Cr}}^{2+}+2{\mathrm{e}}^{-}\rightleftharpoons \mathrm{Cr} {\mathrm{E}}^{⊝}=-0.91 \mathrm{V} \\ {\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}+14{\mathrm{H}}^{+}+6{\mathrm{e}}^{-}\rightleftharpoons 2{\mathrm{Cr}}^{3+}+7{\mathrm{H}}_2\mathrm{O} {\mathrm{E}}^{⊝}=+1.33 \mathrm{V} \\ {\mathrm{Cl}}_2+2{\mathrm{e}}^{-}\rightleftharpoons 2{\mathrm{Cl}}^{-} {\mathrm{E}}^{⊝}=+1.36 \mathrm{V} \end{gathered}$$

Suggest a suitable reagent from the given data that can carry out the oxidation of ${\mathrm{Cl}}^{-}$ ions to ${\mathrm{Cl}}_2$.

$$\begin{gathered} {\mathrm{Cl}}_2+2{\mathrm{e}}^{-}\rightleftharpoons 2{\mathrm{Cl}}^{-} {\mathrm{E}}^{⊝}=+1.36 \mathrm{V} \\ {\mathrm{SO}}_4^{2-}+2{\mathrm{e}}^{-}\rightleftharpoons {\mathrm{SO}}_2 {\mathrm{E}}^{⊝}=+0.17 \mathrm{V} \\ {\mathrm{Cr}}^{2+}+2{\mathrm{e}}^{-}\rightleftharpoons \mathrm{Cr} {\mathrm{E}}^{⊝}=-0.91 \mathrm{V} \\ {\mathrm{F}}_2+2{\mathrm{e}}^{-}\rightleftharpoons 2{\mathrm{F}}^{-} {\mathrm{E}}^{⊝}=+2.87 \mathrm{V} \end{gathered}$$

Use the cell voltage method to predict whether the following reaction is feasible or not. If a reaction does occur, write a balanced equation for it. Can ${\mathrm{MnO}}_4^{-}$ ions oxidise ${\mathrm{Cl}}^{-}$ ions to ${\mathrm{Cl}}_2$ in acidic conditions?

$$\begin{gathered} {\mathrm{MnO}}_4^{-}+8{\mathrm{H}}^{+}+5{\mathrm{e}}^{-}\rightleftharpoons {\mathrm{Mn}}^{2+}+4{\mathrm{H}}_2\mathrm{O} {\mathrm{E}}^{⊝}=+1.52 \mathrm{V} \\ {\mathrm{Cl}}_2+2{\mathrm{e}}^{-}\rightleftharpoons 2{\mathrm{Cl}}^{-} {\mathrm{E}}^{⊝}=+1.36 \mathrm{V} \end{gathered}$$

Use the cell voltage method to predict whether the following reaction is feasible or not. If a reaction does occur, write a balanced equation for it. Can ${\mathrm{MnO}}_4^{-}$ ions oxidise ${\mathrm{F}}^{-}$ ions to ${\mathrm{F}}_2$ in acidic conditions?

$$\begin{gathered} {\mathrm{MnO}}_4^{-}+8{\mathrm{H}}^{+}+5{\mathrm{e}}^{-}\rightleftharpoons {\mathrm{Mn}}^{2+}+4{\mathrm{H}}_2\mathrm{O} {\mathrm{E}}^{⊝}=+1.52 \mathrm{V} \\ {\mathrm{F}}_2+2{\mathrm{e}}^{-}\rightleftharpoons 2{\mathrm{F}}^{-} {\mathrm{E}}^{⊝}=+2.87 \mathrm{V} \end{gathered}$$

Use the cell voltage method to predict whether the following reaction is feasible or not. If a reaction does occur, write a balanced equation for it. Can ${\mathrm{H}}^{+}$ ions oxidise ${\mathrm{V}}^{2+}$ ions to ${\mathrm{V}}^{3+}$ ions?

$$\begin{gathered} {\mathrm{H}}^{+}+{\mathrm{e}}^{-}\rightleftharpoons \frac{1}{2}{\mathrm{H}}_2 {\mathrm{E}}^{⊝}=0.00 \mathrm{V} \\ {\mathrm{V}}^{3+}+{\mathrm{e}}^{-}\rightleftharpoons {\mathrm{V}}^{2+} {\mathrm{E}}^{⊝}=-0.26 \mathrm{V} \end{gathered}$$

Use the cell voltage method to predict whether the following reaction is feasible or not. If a reaction does occur, write a balanced equation for it. Can ${\mathrm{H}}^{+}$ ions oxidise ${\mathrm{Fe}}^{2+}$ ions to ${\mathrm{Fe}}^{3+}$ ions?

$$\begin{gathered} 2{\mathrm{H}}^{+}+2{\mathrm{e}}^{-}\rightleftharpoons {\mathrm{H}}_2 {\mathrm{E}}^{⊝}=0.00 \mathrm{V} \\ {\mathrm{Fe}}^{3+}+{\mathrm{e}}^{-}\rightleftharpoons {\mathrm{Fe}}^{2+} {\mathrm{E}}^{⊝}=+0.77 \mathrm{V} \end{gathered}$$