MadSci Network: Physics

Re: how do all the particles in liquid nitrogen get so cold?

Date: Wed Jan 6 15:20:31 1999
Posted By: Malcolm Tobias, Post-Doc, Physics, Washington University
Area of science: Physics
ID: 912392429.Ph

Liquid nitrogen is cold for the same reason that ice cubes are cold,
someone has gone through the trouble of cooling it down.  
Nitrogen freezes at a very low temperature (-350 degrees F) 
and becomes a gas at (-320 degrees F).  So even if the temperature 
outside was -100 degrees F nitrogen would still be a gas.  In fact, 
most of air (about 80% of it) is made of nitrogen.  It's estimated
that the earth's atmosphere contains 4000 trillion tons of nitrogen!

Nitrogen is not cold by itself, in the same sense that water isn't
inherently warm or cold.  In order to produce liquid nitrogen, you
need to cool nitrogen gas down below -320 degrees F (but not below
-350 degrees F or it will be frozen).  This must be done with
a refrigerator of some sort, that can reach this low of a temperature.

The reason that liquid nitrogen is used so often, is that nitrogen
is relatively inert, which is a fancy way of saying that it doesn't
like to interact with other elements.  Because of this, you don't have
to worry about side effects of dipping shrimp in a vat of liquid
nitrogen to freeze it.  

Current Queue | Current Queue for Physics | Physics archives

Try the links in the MadSci Library for more information on Physics.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-1998. All rights reserved.