An electrolytic cell is constructed for preparing hydrogen. For an average current of 1 ampere in the circuit, the time required to produce 450 mL of hydrogen at NTP is approximately.

22,400 ml H2 at STP = 1 mol H2∴ 450 mL H2 at STP =450 mL22,400 mL×1 mole H2=0.02 molElectrode reaction: 2H++2e−→H22 F                       1 molSo, the liberation of 0.02 mole of H2 requires                   =2×96,500×0.02C=3860 CTime required to produce 0.02 mole t =QI=3,8601=1.07 h≈1 hour