When I was an undergraduate, a friend of mine worked for a physics prof who was researching something with superconductors. He cooled his experiments with liquid nitrogen. So we had a ready source.
We started by chilling our soft drinks with liquid nitrogen, then someone came up with the idea of sealing nitrogen into a 2-liter coke bottle. A coke bottle swells up to about double its original size before it pops, and it makes a most satisfying noise when it does. We'd use 1/2 liter of LN and wait about 10 minutes.
From there, we went to aerial explosions. Fill six trash bags with helium, tie them to a coke bottle of nitrogen, and let them float away. Ten minutes later, boom from somewhere high up and down wind.
I would like to take credit for all this, but in truth most of it was other guys' ideas. I was an enthusiastic implementor, though.
We started by chilling our soft drinks with liquid nitrogen, then someone came up with the idea of sealing nitrogen into a 2-liter coke bottle. A coke bottle swells up to about double its original size before it pops, and it makes a most satisfying noise when it does. We'd use 1/2 liter of LN and wait about 10 minutes.
From there, we went to aerial explosions. Fill six trash bags with helium, tie them to a coke bottle of nitrogen, and let them float away. Ten minutes later, boom from somewhere high up and down wind.
I would like to take credit for all this, but in truth most of it was other guys' ideas. I was an enthusiastic implementor, though.