The electrical energy required : 0.082 F
Further explanation
Given
1.000L of H₂ at 25°C and 1.00 atm
Required
Electrical energy
Solution
Redox reactions in water electrolysis :
Anode: 2H2O (l) → O2 (g) + 4H⁺ (aq) + 4e
Cathode: 4H2O (l) + 4e → 2H2 (g) + 4OH⁻ (aq)
Reaction: 2H2O → 2H2 (g) + O2 (g)
mol H₂ :
n = PV/RT
n = (1 atm x 1 L)/(0.082 x 298)
n = 0.041
From reaction at cathode : mol ratio of electron and H₂ = 4 : 2, so mol electrons :
= 4/2 x mol H₂
= 2 x 0.041
= 0.082
1 Faraday is the amount of electricity that is passed in the electrolysis cell to obtain 1 mole of electrons.
1 Faraday = 1 mole of electrons = 96500 Coulombs
So the energy required :
0.082 Faraday
