The standard free energy change $($ in $J)$ for the reaction $3 Fe^{2+}_{(aq)} + 2 Cr_{(s)} \rightleftharpoons 2 Cr^{3+}_{(aq)} + 3 Fe_{(s)}$ given $E_{Fe^{2+}/Fe}^{\circ} = -0.44 \, V$ and $E_{Cr^{3+}/Cr}^{\circ} = -0.74 \, V$ is $(F = 96500 \, C)$.

What advantage do the fuel cells have over primary and secondary batteries?

In a dry cell,the reaction which takes place at the zinc anode is:

The standard reduction potentials at $298 \ K$ for the following half-cells are given below:
$Cr_2O_7^{2-} + 14H^+ + 6e^- \rightarrow 2Cr^{3+} + 7H_2O$,$E^{\circ} = 1.33 \ V$
$Fe^{3+} + 3e^- \rightarrow Fe$,$E^{\circ} = -0.04 \ V$
$Ni^{2+} + 2e^- \rightarrow Ni$,$E^{\circ} = -0.25 \ V$
$Ag^+ + e^- \rightarrow Ag$,$E^{\circ} = 0.80 \ V$
$Au^{3+} + 3e^- \rightarrow Au$,$E^{\circ} = 1.40 \ V$
Consider the given electrochemical reactions. The number of metal$(s)$ which will be oxidized by $Cr_2O_7^{2-}$ in aqueous solution is $.....$

$Ag/AgCl_{(s)}/KCl$ electrode is

For the reaction $Cu^{2+}_{(aq)} + Fe_{(s)} \rightleftharpoons Fe^{2+}_{(aq)} + Cu_{(s)}$,calculate $\Delta G^o$ in Joules.
Given: $E^o_{Cu^{2+}/Cu} = +0.34 \ V$,$E^o_{Fe^{2+}/Fe} = -0.44 \ V$.