Liquid Nitrogen Shrinking Balloon

Materials: ★★★ Requires materials not commonly found in school laboratories
Difficulty: ★★☆ Can be done by science teachers
Safety: ★★★ Only to be attempted with adequate safety procedures and trained staff

Categories: Liquid Nitrogen

Alternative titles: Liquid Nitrogen and a Balloon

Summary

A balloon filled with air dramatically shrinks when cooled with liquid nitrogen, then re-expands as it warms up again.

Procedure

Put on safety glasses and cryogenic gloves.
Inflate a balloon and tie it securely.
Using metal tongs, hold the balloon while carefully pouring liquid nitrogen over its surface.
Observe as the balloon rapidly shrinks due to cooling.
Hold the balloon up and allow excess nitrogen to drip off.
As the balloon warms in the air, watch it expand back to its original size.
Speed up the process by gently blowing warm air on the balloon.

Links

Pressure Demo: Balloons in Liquid Nitrogen - Physics Demos:

📄 Liquid nitrogen + balloon - Fizzics Education: https://www.fizzicseducation.com.au/150-science-experiments/heat-experiments/liquid-nitrogen-balloon-2/?srsltid=AfmBOooC_Bl6G-_P6bHV3ByJD_uoLPUqYEnt-3BqvwbrqneoY1bxuxVJ

Variations

Use multiple balloons to create a before-and-after display for dramatic effect.

Safety Precautions

Safety glasses required.
Wear cryogenic gloves when handling liquid nitrogen.
Use metal tongs - never hold the balloon directly while pouring nitrogen.
Perform in a well-ventilated area.
Be cautious of the balloon popping if overstressed from temperature change.
Never allow liquid nitrogen to become trapped inside the balloon.

Questions to Consider

Why does the balloon shrink when cooled by liquid nitrogen?
How does Charles’s Law explain this phenomenon?
Why does the balloon expand again as it warms up?
Would helium-filled balloons behave differently from air-filled balloons? Why?
How does this demonstration help us understand how gases behave in weather and everyday life?