Fire & Ice

Pre-Visit Activity:

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.

Post-Visit Activity:

Expanding Ice

Materials:
2 empty plastic soda bottles
small piece of paper
water
tape
food coloring
freezer

What to do:

1. Make four small tabs or markers from the paper. Tape two on each of the bottles at the same height.
2. Color some water with food coloring. Then fill each bottle exactly to the paper mark.
3. Place one bottle in a warm room and the other in your freezer. Leave them overnight.
4. Take out the frozen one and compare the water level of each of them. What happened? What do you notice?
5. The bottle from the freezer seems to have more. Actually, the water expanded and got larger when frozen. This is why pipes in your house sometimes burst in the winter.

Vocabulary:

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

Books:
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

Internet Sites for Kids:
Bill Nye, the Science Guy
Kids World - Science
The Science Club
Dragonfly Magazine

Internet Sites for Teachers:
The Educator's Reference Desk
Annenberg/CPB Resources
Microsoft Lesson Collection

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