You will need ice cubes and salt. Put a pinch of salt on the middle of an ice cube. Leave it in a cool place for ten minutes. What happens to the ice cube?
Ice doesn't melt until it reaches zero degrees Celsius. This is its melting point. When you add salt to the ice, the salt lowers the melting point of the ice, so that it does not have to reach zero degrees Celsius to melt. That is why the salty middle of the ice cube changes into water, while the outside of the cube stays frozen.
2 empty plastic soda bottles
small piece of paper
What to do:
Cryogenics – the study of the behavior of objects at extremely low temperatures
Dewar – a two-chambered container that stores the liquid nitrogen
Physics – the study of how things work, and how forces work on objects
Vacuum – the absence of molecules
Evaporation – the process by which a liquid changes into a gas or vapor
Condensation – the change from a vapor into a liquid
Bingham, Jane – The Usborne Book of Science Experiments
Craig, Annabel – The Usborne Science Encyclopedia
Ehrlich, Robert – What if? Mind Boggling Science Questions for Kids
VanCleave, Janice – Chemistry for Every Kid: 101 Easy Experiments That Really Work