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.



  • [1] 1L Dewar filled at least 2/3 full of liquid nitrogen
  • [1] Balloon (plus spares)
  • [1] Air pump 

Safety Equipment

  • [1] Safety goggles
  • [1] Safety gloves

Classroom Assembly

  1. Place the Dewar on the lecturn shelf. 
  2. Inflate a balloon using the air pump. Do not overinflate or the balloon will not fit in the Dewar.

Important Notes

  • Liquid nitrogen can cause severe burns and blindness. Use with caution.
  • The balloons pop easily. Bring extra.


  1. Put on your safety goggles and gloves.
  2. Place the balloon in the dewar of liquid nitrogen. As it cools, it will deflate.
  3. When the balloon has deflated significantly, remove from the liquid nitrogen and show the class.
  4. Continue to hold up the balloon. As it warms, it will expand.


Additional Resources


  • PIRA 4E10.20


  • Don't attempt this at home!

Last revised

  • 2018


Related AV

Related demos


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.