Liquid Nitrogen Demos
- and -
Shrinking Wrap with a Vacuum presented at Southern Mississippi Universityon July 13, 2000

Construction:
    Before doing the demo, obtain a ping pong ball.  The ones with a pattern on them work best.
If you have white ones, use a marker to add some color or pattern.  Using a straight pin, poke a tangential hole in the ping pong ball.  With the students, tell them that you will put the ping pong ball into the liquid nitrogen so that the liquid will flow into the ball.  Use tongs to submerge the ping pong ball into the liquid nitrogen.  The ball will be bouyant so hold it under the liquid for 30 seconds so that the liquid will flow into the hole.  Use the tongs to remove the ball and place it on a table inside the circle of the hula hoop.  The nitrogen in the ball will warm to room temperature and convert to a gas.  The gas expands and as it leaves the hole in the ball, the force pushes the ball into a circular motion.  Occasionally the ball needs a little nudge to get it started with a light touch of the finger.  This also provides a small amount of heat.

Liquid Nitrogen Safety:

   1. It is extremely cold: 77.3K = -196C = -320F at atmospheric pressure. This can cause severe frost bite.
   2.Treat liquid nitrogen and any object cooled with liquid nitrogen with respect.
   3.Take care not to allow liquid nitrogen to be trapped in clothing near the skin.
   4.Wear safety glasses or a face shield when transfering liquid nitrogen.
   5.Wear gloves when touching any object cooled by liquid nitrogen. Gloves should be loose fitting, so they could be thrown off if liquid were to pour inside them.
   6.Use only approved unsealed containers. Never pour it into a coffee thermos. Never seal it in any container (it will explode).
   7.Never dip a hollow tube into liquid nitrogen; it may spurt liquid.
   8.Never use in a small poorly ventilated room, and never dispose of liquid nitrogen by pouring it on the floor. It could displace enough oxygen to cause suffocation. Nitrogen gas is colorless and odorless--the cloud thatforms when you pour liquid nitrogen is condensed water vapor from the air, not nitrogen gas.
   9.Do not store liquid nitrogen for long periods in an uncovered container (on the other hand, never totally seal a container). Because the boiling point of oxygen, 90.1K, is above that of nitrogen, oxygen can condense from the air into the liquid nitrogen. If the air over the nitrogen circulates, this liquid oxygen can build up to levels which may cause violent reactions with organic materials; even materials which are ordinarily nonflammable.

For more information click here:  Liquid Nitrogen Safety (this link takes you away from the PSLC)

Incredible Shrinking Person
Click here to see the directions (this link takes you away from the PSLC)

Wayne Goates, Mr Booger Hollow, is holding the shop vac while Lynn Higgins is
helping shrink their friend.

Egg in a Bottle
Click here to see the directions (this link takes you away from the PSLC)


Remember, the egg does not SUCK!  These are forces at work.

PSLC OFFERS THIS SITE AS AN EDUCATIONAL TOOL. PSLC IS NOT RESPONSIBLE FOR ANY INJURY OR DAMAGE CAUSED TO ANY PERSON, DIRECTLY OR INDIRECTLY, RELATING TO ANY OF THE DEMOS OR EXPERIMENTS LISTED AT THIS SITE. YOU ARE WHOLLY RESPONSIBLE FOR YOUR SAFETY.

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