Dioxygen on a large scale or commercial scale is obtained by two following methods :
(1) From water : By electrolysis of acidified water, H2 gas is obtained at the cathode and O2 is obtained at anode.
(2) From air :
- Carbon dioxide and water vapour is removed from air and the remaining gases are liquefied.
- O2 on large scale is obtained by fractional distillation of liquid air.
- On distillation, liquid dinitrogen having low boiling point distils out first leaving behind liquid dioxygen. Then liquid O2 is distilled out and separated.
