Re: How to make liquid nitrogen?

Area: Chemistry
Posted By: Richard Oldroyd, Post-doc/Fellow Davy-Faraday Research Laboratory
Date: Thu Jun 5 04:05:00 1997
Area of science: Chemistry
ID: 863506643.Ch

Message:

Liquid nitrogen is made in bulk from the fractional distillation of liquid air. The basic process involves cooling air to below the boiling point of all the component gases and gradually raising the temperature to allow the boiling off, and subsequent removal, of each gas in turn.

In the case of air, the components boil off in this order:

Nitrogen........ -210 degrees C
Oxygen.......... -193 degrees C
Argon........... -189 degrees C

(Carbon dioxide solidifies at -78 degrees C, so is easily removed)

Once the evolved gas, or fraction, has been separated, it can then be cooled down again to make it liquid.

A short summary can be found at BOC's Web site.

Best wishes

Richie.....

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