Normally, touching Liquid Nitrogen would be a very, very bad idea. Liquid Nitrogen freezes living tissue immediately on contact, and is used as a coolant for machinery. Being such a coolant if touched it will cause severe frostbite, which is the reason you don't normally want to come in contact with it. There is, however, a way to touch liquid nitrogen without any side effects besides becoming extremely cold. This is achieved through the Leidenfrost Effect. When liquid comes into contact with any material significantly higher than its boiling point, such as a hot metal plate, it will instantly evaporate and cause a cushion of gas between the rest of the liquid and the hot plate. This means that if water, for example, was poured onto extremely hot metal it would float on a cushion of gaseous H2O rather than come in contact with the metal plate. This effect doesn't last forever, but if you put your hand in liquid nitrogen that is on such a hot surface (as in the video linked below) you can come out unscathed provided you don't keep your hand in too long.
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This is pretty cool; a guy came to my middle school and did this. Of course at the time i had no idea how he did it without freezing his hands.
ReplyDeleteRobert Stenger
The only time you would want to have liquid nitrogen not under the Liedenfrost Effect come in contact with your skin is if you are attempting to freeze a wart. The liquid nitrogen kills the blood vessels that "feed" the wart, causing the wart to die.
ReplyDeleteDora Moore