Heat and Liquid Nitrogen
- Clouds
- Soda bottle explosion, set up
- Liquid nitrogen and balloons
- Liquid nitrogen and flower
- Liquid nitrogen cannon
- Banana and nail
Clouds
Throw a polystyrene coffee cup full of liquid nitrogen high into the
air.
Don't throw the cup! A cloud will temporarily be formed. This shows
that
if you cool the air enough, the water vapor in it condenses.
Balloons in Liquid Nitrogen
Pour liquid nitrogen over an air filled balloon, it will collapse in a
vivid demonstration of the relationship between temperature and volume
for a fixed mass of gas at a constant pressure. If immersed in a
container
of liquid nitrogen, the air in the balloon liquefies. Try it with
helium
instead of air, that way the balloon ascends when it warms, a nice
discrepant
event.
Carnations in Liquid Nitrogen
Flowers are frozen in liquid nitrogen and then smashed, showing that
temperature
has a dramatic effect on the properties of materials, especially if
they
contain water.
Liquid Nitrogen Cannon
The world's best pop-gun can be made from a piece of steel pipe, closed
at one end, and a small metal 'test tube' fastened to a short length of
wire, used as a dipper. Fill the dipper with liquid nitrogen after
having
cooled it in the nitrogen. Carefully lower this dipper with liquid
nitrogen
into the pipe and cork off the pipe. When the pipe is shaken the liquid
spills from the dipper and rapidly becomes a gas when it contacts the
pipe.
The gas produced when the liquid nitrogen vaporizes, at atmospheric
pressure
occupies about one thousand times the volume of the liquid. Confinement
in the tube causes high pressure and violent expulsion of the cork.
Explosion of a Soda Bottle
A 2-liter soda bottle is tightly capped off with about a pint of liquid
nitrogen in it. Then it is placed on the ground with a 50 gallon
plastic,
not metal, garbage can inverted over it. It takes a few minutes before
the bottle explodes and projects the garbage can 10 to 20 meters into
the
air. This demonstration of a liquid turning into a gas should never
be done in a small room and should only be done in a large room, such
as
a gymnasium, with a plastic garbage can over the bottle to muffle the
noise.
Outside using a 2-liter bottle with a cup of liquid nitrogen, it's
louder
than both barrels of a 12-gauge shotgun going off together and the
small
pieces of frozen plastic will be both sharp and fast moving, so make
sure
no one is within 30 meters or so of it.
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