Science researcher and AVS father Henry lit up – or shall we say “deflated and inflated” — a recent morning meeting with a liquid nitrogen experiment involving balloons.
Here’s what he did. Henry put on safety goggles. Behind a Plexiglas window, he took a tall canister filled with liquid nitrogen and poured some into a smaller, metal container. Next, Henry took an inflated pink balloon and slowly fed it into the smaller container. What happened? Check out the video: Balloon Experiment Video_AVSfall2015
It looked like the container sucked the air out of the balloon! It deflated. When Henry took the balloon out of the canister with a pair of tongs…it re-inflated!!
He asked the room full of kids, “Is this science, or is this magic?” They shouted, “Science!”
What happened? It turns out the air was still inside the balloon when the balloon was in the canister. The liquid nitrogen cooled the air in the balloon so much that the balloon collapsed. Why does this happen? It’s all about the compression of gasses — and the expansion of gasses at different temperatures. In this case, the air pressure on the balloon remained the same. And the number of molecules of gas in the balloon remained the same. What changed was the liquid nitrogen lowered the space that gas took up inside the ballon because it cooled the gas so much.
After a large round of applause, the kids shouted, “Let’s see it again!”