How can you fit a bunch of balloon animals into a small container? Add some liquid nitrogen into the mix, as demonstrated in this video by Real Physics Live, the YouTube channel for Texas A&M University’s Department of Physics and Astronomy.
What’s going on? “Liquid nitrogen is nitrogen in a liquid state at an extremely low temperature.” It shrinks up the animals as the oxygen and nitrogen gases within the balloons cool and condense. When the shriveled balloons are taken out of the dewar and returned to room temperature, the gases expand, returning the balloon animals to their original volume.
Per TSG Physics’ demo of the same phenomenon, “This demonstrates the ideal gas law (PV=nRT) which states that a drop in temperature with fixed mass and external pressure will result in a smaller volume, and vice versa.”
Reminder: Safety glasses, cryogenic protective gloves, and parental supervision required. Liquid nitrogen can splash into eyes or cause frostbite with prolonged contact with skin. MAKE has safety recommendations here: Liquid Nitrogen Basics for the Home Chef.
Plus, watch TED Ed’s The ABCs of Gas.