Recognise Changes of State: Freezing and Condensing

Solids, liquids and gases change state when they are heated, but also when they are cooled. We are going to find out exactly what happens when substances in different states are cooled.

Freezing and condensing are words that we use to describe changes of state - they happen when a substance is cooled.

A liquid will turn into a solid when cooled. This process is called freezing.

A gas will turn into a liquid when cooled. This process is called condensing. 

So what do you think is happening to the particles during these changes of state?

Well, when cooled, particles in a substance lose energy. This means that they can move around less and when they lose enough energy, they move closer together and eventually change state.

Got it? Let's try some questions on cooling and the resulting changes of state.