17 July 2009
How to dip your hand into liquid nitrogen
The Leidenfrost effect is a phenomenon in which a liquid, in near contact with a mass significantly hotter than the liquid's boiling point, produces an insulating vapor layer which keeps that liquid from boiling rapidly. This is most commonly seen when cooking; one sprinkles drops of water in a skillet to gauge its temperature--if the skillet's temperature is at or above the Leidenfrost point, the water skitters across the metal and takes longer to evaporate than it would in a skillet that is above boiling temperature, but below the temperature of the Leidenfrost point. It has also been used in some dangerous demonstrations, such as dipping a wet finger in molten lead or blowing out a mouthful of liquid nitrogen, both enacted without injury to the demonstrator."
Via Reddit.
FYI - A science teacher who tried to DRINK liquid nitogen tells his story at the Darwin Awards.
Addendum - other things you can do with liquid nitrogen (credit Cornell Univesity mad scientists, with many more at the link). Hat tip to Ambuj who knew of the link.
# Put on a rubber surgical glove with a hot dog (sausage) stuck in one of the fingers. Put the hot dog in the liquid nitrogen and then, to the amazement of your friends, smash your "finger" with a hammer. Comment: Keep in mind which finger...
# Break a light bulb, put the filament into liquid nitrogen and turn it on. Looks cool!
# Freeze a can of shaving cream and then peel the can away from the cream. Put the canless cream into someone's car. Let the oven-like heat from the car's sitting in the sun defrost the shaving cream. Two cans will fill an entire car.
# One thing we used to do for smaller groups was to freeze a graham cracker and then eat it. The vapors released through your mouth and nose are quite dramatic and it really does titillateyour tastebuds! Of course, we usually waved the cracker around just a little before eating it to be sure no drops of the really cold stuff linger.
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I tried this when I was in first year at college. It is pretty cool (both the experiment and Liq N2). I actually juggled a handful of it between the hands without managing to get a frost bite. Then I used it to liquefy air and wash my hands in the condensing stream. I still tell my friends of this story and very few believe it. I am going to bookmark the video to show them if anyone doubts it now. Thanks.
ReplyDeleteThe only trick I never tried was that it is possible to put half teaspoon of Liq N2 in your mouth without risking burning anything. I was too afraid to try this.
ReplyDeletePlaying with liquid nitrogen like this is crazy but cool!
ReplyDeleteDon't know many people who would do something like this.
Here's a fun list of things to do with Liquid N2.
ReplyDeleteI remember my high school chemistry teacher doing the hotdog in the glove trick in front of the class. I also remember her as a sadist.
ReplyDelete