Answer:
Here we will find the amount of current required for the electrolysis of water as follows:
PV = nRT ....................................... ideal gas
n = PV/(RT)
where
P= 715 Torr = 715 x 0.133kPa =95.3kpa
T=25 ∘C = 298k
V = 13.8 mL = 13.8 x 10⁻⁶m³
R=8.314J/mol.k
No. of moles of H₂, n = 95.3 × 10³ x 13.8 x 10⁻⁶ / (8.314 × 298) = 5.31 × 10⁻⁴ mol
To produce H₂ gas, we have the reaction,
2H⁺(aq) + 2e⁻ → H₂(g)
According to the equation above, the production of 1 mole of H₂ needs 2moles of electron, e⁻.
Number of moles of e⁻ = (5.31 × 10⁻⁴) × 2 = 1.06 × 10⁻³ mol
Each molecules of e⁻ carries 96500 C of electricity.
Amount of electricity, Q = 96500 × (1.06 × 10⁻³) = 102.47 C
Q = It
Current, I = Q/t = 102.47 / (4 × 60) = 0.426 A
