A demonstration of a rapid change of state using liquid nitrogen. A melted ice lolly is submerged in liquid nitrogen, at which point it turns back into an ice lolly and is frozen. This demonstrates a rapid change of state. The experiment is repeated using a balloon full of air. A cartoon is used to illustrate particle theory of a gas turning to a liquid and vice versa.

This clip is from:
Science Clips, Changing State
First broadcast:
11 October 2007

Students could use the information presented in this clip to predict what will happen to a range of substances when subjected to a change in temperature. This could include liquid water, chocolate, or our breath. Students could say what they believe will happen if each is heated or cooled, and then conduct an experiment to test their hypothesis. They could use flow diagrams to show the processes they observe.

Students could also explore the particle theory of changes in state in a practical demonstration. Ask students to take on the role of particles and to arrange themselves as a solid. When heated, they could break arms and move around each other whilst still staying very close as they form a liquid. As they continue to be heated they can break apart and run around the room as a gas. This could become a game where temperatures could be called out and students could react as they are heated and cooled to form different states of matter.