# How can pure oxygen be obtained from air?

Feb 6, 2017

#### Explanation:

This is not a reaction I would be happy doing, and is the preserve of the specialist. Industrially, they compress, and liquefy air, and then perform a fractional distillation. The normal boiling point of dinitrogen is $- 196$ ""^@C; the normal boiling point of dioxygen is $- 183$ ""^@C, and the difference in principle allows separation. Liquid nitrogen is inert (but it is still a cryogenic liquid that could cause burns); I have written here before, that a Dewar of liquid nitrogen is one of the best fire extinguishers; of course, the fire might light up again after the nitrogen boils off.

Liquid oxygen is likewise very cold, but an oxidant par excellence, and something that would have to be very carefully handled. If you have ever seen a magic show, you might see some spectacular demonstrations of combustion using liquid oxygen.