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 $96.5mA$ current, how long will it deliver power?
(Assume $1F=96500C/mole$ 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 $z=\frac{\text{ At. }wt\text{ . }}{nF}$

(ii) Also,

$H_2+\frac{1}{2}{O}_2⟶H_{2}O$

Given, $1mol$ of $H_2$

$10mol$ of $O_2$

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

Hence $n=2$

$i=96.5mA=0.965A$

$t$ (time ) $=\frac{W}{zi}=\frac{W}{\frac{At.Wt}{nF}\times i}=\frac{nF}{i}$

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