a$.$ A polymer electrolyte membrane fuel cell $($PEMFC$),$ producing liquid

water, operates at $80C$ on air $(1$atm$)$ on the cathode side with the volume

fraction given in Table $1.$ The anode side is fed with pure hydrogen $(1$atm$).$

Calculate the cell voltage for this cell when there is no current drawn. Write

the half$-$cell reactions at the cathode and anode, together with the overall cell

reaction. Will this cell voltage remain constant when the current starts to

flow? Discuss your answer.

Table $1.$ Composition of air

Table $2$ Variation of $G_r$ of $H_2+\frac{1}{2}{O}_2{H}_{2}O$ as a function of temperature