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A Crazy Guy Sticks His Hand in Liquid Nitrogen


Image credit: David Monniaux, via Wikimedia Commons.

Placed under normal atmospheric pressure, nitrogen could become a liquid between -210°C and -195.8°C (-346°F to -320.44°F). That is amazingly cold. You may remember that in your classroom, teachers demonstrated how to put different objects into nitrogen and then shatter them. Therefore, it would be considered a bad idea to shove your hand in a bucket full of it.

Actually your hand would not seriously hurt because of the Leidenfrost effect, which could be observed when cooking with a very hot pan.

If the surface is hot enough to exceed the boiling point of the liquid, water droplets would ball up into small dancing beads rather than evaporate immediately. The reason for it is that an insulating vapor layer takes shape between the liquid and the hot surface so as to keep the rest of the water away from the hot surface. This reaction helps slow the heat transfer between the liquid and the hot surface, thus preventing the liquid from further evaporation.

This phenomenon is also clearly noticeable if liquid nitrogen is put to be contact with an object under the room temperature, like your hand. Check out this video for a demonstration:

Source: IFLScience