Video: Watch this demo
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
- Protective gloves and tongs
- Using the wrench, take off the cover to the metal casing.
- Fill the casing up with water. Put the cover back on tight with the wrench.
- Pour some liquid nitrogen into the pressure cooker (about 3-4 inches deep).
- Place the ice bomb into the LN2 with the tongs. Place the wood cover on top of the pressure cooker.
- Wait several minutes until the ice bomb cracks. Take out the pieces with the tongs.
- 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.
Use caution when working with liquid nitrogen, as it is very cold.