Lawrie Ryan and Roger Norris Solutions for Chapter: Transition Elements, Exercise 4: Question

Write two half-equations for the reactions that take place when ${\mathrm{Fe}}^{2+}\left(\mathrm{aq}\right)$ is oxidised by dichromate $\left(\mathrm{VI}\right)$ ions,

Give the overall reaction of oxidation of ${\mathrm{Fe}}^{2+} \left(\mathrm{aq}\right)$ by dichromate $\left(\mathrm{VI}\right)$ ions by combining its half cell reactions.

Work out the ${\mathrm{E}}^0$ value of the cell made when the two half-cells shown below are connected and the overall reaction takes place. Discuss and explain what this value predicts about the likelihood of ${\mathrm{Fe}}^{2+} \left(\mathrm{aq}\right)$) being oxidised by dichromate $\left(\mathrm{VI}\right)$ ions,
$$\begin{gathered} \frac{\mathrm{Oxidation}: 6{\mathrm{Fe}}^{2+} \left(\mathrm{aq}\right) \to 6{\mathrm{Fe}}^{3+} \left(\mathrm{aq}\right) + 6{\mathrm{e}}^{-} \\ \mathrm{Reduction}: {\mathrm{Cr}}_2{\mathrm{O}}_7^{2-} \left(\mathrm{aq}\right) + 6{\mathrm{e}}^{-} + 14{\mathrm{H}}^{+}\left(\mathrm{aq}\right)\to {\mathrm{Cr}}^{3+}\left(\mathrm{aq}\right) + 7{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}{14{\mathrm{H}}^{+}( \mathrm{aq}) + 6{\mathrm{Fe}}^{2+} \left(\mathrm{aq}\right) + {\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}\left(\mathrm{aq}\right) \to 6{\mathrm{Fe}}^{3+} + 2{\mathrm{Cr}}^{3+} \left(\mathrm{aq}\right) + 7{\mathrm{H}}_2\mathrm{O} \left(\mathrm{l}\right)} \end{gathered}$$

How many moles of ${\mathrm{Fe}}^{2+} \left(\mathrm{aq}\right)$ can $1$ mole of dichromate$\left(\mathrm{VI}\right)$ oxidise?