Question

How many liters of O2 at 298 K and 1.00 bar are produced in 2.25 hr in an electrolytic cell operating at a current of 0.0400 A?

Answer 1

Coulombs used = I x t

                          = 0.040 Amp x 2.25 h x 60 x 60

                          = 324 C

moles electron used = 324/96500 = 0.00336 mol e-

It takes 4 e- to form O2

So,

moles O2 produced by 0.00336 mol e- = 0.00336/4 = 0.00084 moles

Volume O2 produced = nRT/P

with,

P = 1.00 bar = 0.987 atm

n = 0.00084 moles

R = gas constant

T = 298 K

So,

Volume O2 = 0.00084 x 0.08205 x 298/0.987

                   = 0.021 L