In this demo, Jared explores the properties of Liquid Nitrogen, which is air cooled to −196°C (−320°F).
Air is composed of 78% Nitrogen and 21% Oxygen, and is usually a gas. When air is cooled to −196°C, the Nitrogen in air condenses, or becomes liquid. This is an example of a phase transition, where a substance changes phase (solid, liquid, or gas) as temperature changes. In the first video, Jared uses Liquid Nitrogen to freeze a racketball — see what happens!
Leaves, which are usually floppy, will freeze when exposed to Liquid Nitrogen! Leaves have a lot of water inside them, and when that water is cooled it freezes, or becomes solid. Like the racketball, when frozen the leaf becomes brittle and easy to shatter.
In this third video, Jared puts a balloon into the Liquid Nitrogen. As the air inside the balloon cools and turns to liquid, the air pressure inside the balloon diminishes, and the balloon crumples. This is reversible; when Jared brings the balloon back into room temperature air, the air inside the balloon becomes a gas again, and the balloon expands back to its original shape.
Finally, Jared pours Liquid Nitrogen into a kettle. As steam shoots out of the kettle, you can hear the Nitrogen boiling, or becoming a gas! The outside of the kettle cools as the Nitrogen takes in heat from its environment to boil.