Question

Consider a fuel cell supplied with $1$ mole of $H_2$ gas and $10$ moles of $O_2$ gas. If fuel cell is operated at $96.5\, mA$ current, how long will it deliver power?
(Assume $1\, F \,= \,96500\, C/mole$ of electrons)

• A. $1 \times 10^6 s$
• B. $0.5 \times 10^6 s$
• C. $2 \times 10^6 s$
• D. $4 \times 10^6 s$
• E. $5 \times 10^6 s$

Answer 1

Answer: (C)

$(i) \because w=$ zit

and $z=\frac{\text { At. } w t \text { . }}{n F}$

(ii) Also,

$H _{2}+\frac{1}{2} O _{2} \longrightarrow H _{2} O$

Given, $1 \,mol$ of $H _{2}$

$10\, mol$ of $O _{2}$

Thus by $1$ mole of $H_{2(g)}$, we get $1 \,mol$ of $H _{2} O$

Hence $n=2$

$ i =96.5\, mA =0.965 \,A $

$ t$ (time ) $=\frac{W}{z i}=\frac{W}{\frac{A t . W t}{n F} \times i}=\frac{n F}{i} $

$t$ ( in sec ) $=\frac{2 \times 96500}{0.0965}=2 \times 10^{6}\, sec $