4C20.20-Ice Bomb

4c2020 ice bomb 3 4c2020ice bomb 4c2020ice bomb 2

Video: Watch this demo

Instructor’s video

Description: This demonstration illustrates a unique property of water: that it undergoes a decrease in density, and expands when freezing, whereas most liquids increase in density as they solidify.


  • Metal iron casing
  • 5/8″ wrench
  • Pressure cooker with wood lid
  • Foam insulator
  • LN2
  • Protective gloves and tongs

Demonstration Procedure:

  1. Using the wrench, take off the cover to the metal casing.
  2. Fill the casing up with water. Put the cover back on tight with the wrench.
  3. Pour some liquid nitrogen into the pressure cooker (about 3-4 inches deep).
  4. Place the ice bomb into the LN2 with the tongs. Place the wood cover on top of the pressure cooker.
  5. Wait several minutes until the ice bomb cracks. Take out the pieces with the tongs.
  6. Explain to students that as the water changes into a solid, its density decreases. This causes pressure to build up inside the casing until finally the iron cracks.

Liquid Nitrogen Liquid Nitrogen
Use caution when working with liquid nitrogen, as it is very cold.