How many Faradays must be supplied to a cell for the electrolytic production of $245 \mathrm{g}$ of ${\mathrm{NaClO}}_4$ from ${\mathrm{NaClO}}_3$ (molar mass of $\left.{\mathrm{NaClO}}_4=122.5 \mathrm{g} {\mathrm{mol}}^{-1}\right)?$

For hydrogen-oxygen fuel cell, the cell reaction is

$2{\mathrm{H}}_2 \left(\mathrm{g}\right)+{\mathrm{O}}_2 \left(\mathrm{g}\right)⟶2{\mathrm{H}}_2\mathrm{O} \left(\mathrm{\ell }\right)$

If ${{\mathrm{\Delta G}}^{°}}_{\mathrm{f}}\left({\mathrm{H}}_2\mathrm{O}\right)=-237.2 \mathrm{kJ} {\mathrm{mol}}^{-1},$ the emf of this cell is

${\mathrm{MnO}}_4^{-}+8{\mathrm{H}}^{+}+5{\mathrm{e}}^{-}⟶{\mathrm{Mn}}^{2+}+4{\mathrm{H}}_2\mathrm{O};$

$\mathrm{E}°=1.51 \mathrm{V}$

${\mathrm{MnO}}_2+4{\mathrm{H}}^{+}+2{\mathrm{e}}^{-}⟶{\mathrm{Mn}}^{2+}+2{\mathrm{H}}_2\mathrm{O}$

$\mathrm{E}°=1.23 \mathrm{V}$

${{\mathrm{E}}^{\circ }}_{{{\mathrm{MnO}}_4}^{-}/{\mathrm{Mno}}_2}$ is