lysis of water can be used as a mathod of preparation of oxygen and hydrogen gas.In an experiment 22.4mL/s oxygen required. How much current has to supplied to carry out the experiment at STP?
Dear Student,
The reaction that takes place when water is electrolysed is
2H2O → 2H2 + O2
The O in H2O has an oxidation number of −2, while the oxidation number of O in O2 is 0. So, the change in oxidation state is 2, and there are 2 O atoms. So, we require 4e− per mole of oxygen gas produced.
1 mole of oxygen gas at STP occupies 22.4L = 0.224 x 105
So, 0.224 ml = 0.224mL of O2 is 10−5 moles of O2.
We require 22.4 ml/s of Oxygen. Therefore we nee 100 x 10−5 moles of O2.
So, we need 10−3×4e− per second.
That is 4 × 10−3 × 6.022 × 1023 × 1.602 × 10−19coulomb / second.
≈ 385.89 A
Regards