A fuel cell has the reactions:
ANODE: $2{\mathrm{A}}_2\underset{ }{\rightleftarrows }4{\mathrm{A}}^{+2}+8{\mathrm{e}}^{-}$
CATHODE: $4{\mathrm{A}}^{+2}+{\mathrm{B}}_2+8{\mathrm{e}}^{-}\underset{ }{\rightleftarrows }2{\mathrm{A}}_2\mathrm{B}$
All data are at 1bar and 298K.
The overall reaction releases 300 MJ per k mole of A₂B product in a calorimeter at Constant pressure.
The entropies of the different substances are:
${\mathrm{A}}_2:200\mathrm{kJ}{\mathrm{K}}^{-1}\mathrm{k}{\mathrm{mole}}^{-1}, {\mathrm{B}}_2:400\mathrm{kJ}{\mathrm{K}}^{-1}\mathrm{k}{\mathrm{mole}}^{-1}, {\mathrm{A}}_2\mathrm{B}:150\mathrm{kJ}{\mathrm{K}}^{-1}\mathrm{k}{\mathrm{mole}}^{-1}$
A₂ and B₂ are gases, whereas A₂B is liquid.
Charge of the electron $=1.6\times {10}^{-19}\mathrm{C}$
Avogadro’s number $=6.022\times {10}^{23}$