Balloons in liquid nitrogen
Thermal expansion/contraction, ideal gas law
A balloon is placed in a vacuum flask of liquid nitrogen. As the balloon cools, it shrinks. When the balloon is removed from the liquid nitrogen, it begins to heat up and expand.
-  1L Dewar filled at least 2/3 full of liquid nitrogen
-  Balloon (plus spares)
-  Air pump
-  Safety goggles
-  Safety gloves
- Place the Dewar on the lecturn shelf.
- Inflate a balloon using the air pump. Do not overinflate or the balloon will not fit in the Dewar.
- Liquid nitrogen can cause severe burns and blindness. Use with caution.
- The balloons pop easily. Bring extra.
- Put on your safety goggles and gloves.
- Place the balloon in the dewar of liquid nitrogen. As it cools, it will deflate.
- When the balloon has deflated significantly, remove from the liquid nitrogen and show the class.
- Continue to hold up the balloon. As it warms, it will expand.
- PIRA 4E10.20
- Don't attempt this at home!
If you have any questions about the demos or notes you would like to add to this page, contact Ricky Chu at ricky_chu AT sfu DOT ca.