Question

In a H 2 fuel cell, electricity is produced by oxidation-reduction reaction between

H 2 and O 2 gases. Draw a diagram of H 2 – O 2 fuel cell and write down the cell

reaction of that fuel cell. At STP 89.6 L H 2 gas is passed in H 2 fuel cell which

reacts with O 2 for 20 minutes. What is the average strength of electricity (in

ampere) produced? If total current produced is passed in CuSO 4 solution of

electrolytic cell, then what amount of Cu metal will be deposited at cathode?

Answer 1

Half cell reaction

H₂ $\to$ 2H⁺ + 2e^-

2H⁺ + 2e^- + $\frac{1}{2}$ O₂ $\to$ H₂O(l)

H₂ + $\frac{1}{2}$ O₂ $\to$ H₂O(liquid)

Charge = current × time

n = $\frac{Q}{ZF}$ ,

n / no. Of moles of H₂ = 896/224 = 4 moles

Q = nZF

Q = 4×2×96500 = 772000 C

Q = I × t

I = $\frac{Q}{t}$ = $\frac{772000}{20}$ = 38600 A

no. of Cu forned

n = $\frac{Q}{ZF}$ = $\frac{772000}{2×96500}$ = 4

Amount is 63.5 × 4 = 254