Concepts

Thermal expansion/contraction, gas law at constant pressure

Overview

An air-filled balloon cooled in liquid nitrogen will shrink. When warmed back up in air, the balloon re-inflates.

Skilled individuals can make balloon animals to dunk in liquid nitrogen. Otherwise, just dunk the balloon "snake."

Details

Equipment

• [1] 1 L Dewar with liquid nitrogen
• [1] Balloon
• [1] Twisting balloon
• [1] Balloon pump
• [1] Forceps

Safety Equipment

• [1] Safety glasses
• [2] Safety glove

Classroom Assembly

1. Place the Dewar on the lecturn shelf. 
2. Inflate a balloon. If using the twisting balloon, leave a 2-inch unfilled section on the end.

Important Notes

• Liquid nitrogen can cause severe burns and blindness. Use with caution.
• The balloons can pop prematurely. Bring extras.

Script

1. Pump air into the balloon until there is only a 2-inch unfilled section on the end.
   
2. Make a balloon animal (dog suggested). Give it a name.
3. Put on your safety glasses and gloves.
4. Put the balloon (mention by name) into the dewar of liquid nitrogen. Use forceps to completely immerse the balloon. Make sounds of dismay as the balloon shrivels up.
5. Pull the balloon out of the liquid nitrogen and perform "CPR" by blowing on it with your warm breath. The balloon should be mostly back in proper form.

Additional Resources