Pick Up An Ice Cube

DESCRIPTION:
This demo picks up an ice cube without lifting it. The salt changes the melting point of the ice cube which “freezes” it to the string, allowing the demonstrator to pick the ice cube up.

TOPICS COVERED:
melting point depression

MATERIALS NEEDED:
– container of water with ice cubes floating near the top
– string
– salt

PROCEDURE:
1. Lay the string across the ice cube
2. Pour salt on it
3. Wait ~30 seconds before picking up

ADDITIONAL COMMENTS:
If you pick up too soon the ice cube isn’t securely frozen to the string, and if you don’t put enough salt on it, it won’t freeze.

SAFETY:
Safety goggles should be worn at all times.

STORY:
The students can be challenged to pick up the ice cube with the string and salt, without lifting the ice cube or touching it.

Handout