How cold is liquid nitrogen?
Under normal atmospheric pressure, nitrogen can exist as a liquid between the temperatures of 63 K and 77.2 K
(-346°F and -320.44°F). Below 63 K, nitrogen freezes and becomes a solid. Above 77.2 K, nitrogen boils and becomes a gas.
Since it is obtained from the atmosphere, liquid nitrogen is inexpensive and is rarely refrigerated. It is kept in insulated containers called Dewars and is allowed to boil away. Since it is boiling, most of the liquid nitrogen used in laboratories and in cryogenics shows is at a temperature of 77.2 K.
Liquid nitrogen looks like boiling water. If you have never seen it, we have a picture of some posted on our site. If you have never seen liquid nitrogen in action, we have filmed some experiments that you can watch, like this:
Steve Gagnon, Science Education Specialist (Other answers by Steve Gagnon)