Experimenting with Liquid Nitrogen: Who's Right?

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SUMMARY

The discussion centers on the demonstration of placing a balloon in liquid nitrogen (LN2) and the misconceptions surrounding the liquid observed inside the balloon. It is established that the liquid seen is primarily liquid oxygen (O2), not water, as water would freeze rapidly in LN2. The presence of argon may also be noted, but water and carbon dioxide would solidify and exist in negligible amounts. The balloon's contents are confirmed to be liquefied gases that were already present before immersion in LN2.

PREREQUISITES
  • Understanding of liquid nitrogen properties and behavior
  • Knowledge of gas liquefaction processes
  • Familiarity with the states of matter, particularly phase changes
  • Basic chemistry concepts related to gases and their interactions
NEXT STEPS
  • Research the properties and applications of liquid nitrogen in scientific demonstrations
  • Learn about the liquefaction of gases, focusing on oxygen and argon
  • Explore safety protocols for handling cryogenic materials
  • Investigate the chemical reactions of oxygen with rubber and other materials at low temperatures
USEFUL FOR

This discussion is beneficial for educators, science demonstrators, and students interested in chemistry and physics, particularly those engaging with cryogenics and gas behavior in educational settings.

Mu naught
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I'm supposed to do a little demonstration to some middle school kids and one thing that's planned is sticking a balloon in liquid N2. The guy who showed us what they want (who doesn't appear to know anything about science) claimed that the liquid you see in the bottom of the balloon when you let it sit in the LN2 is water, but I said no that can't be because water would freeze very quickly and the liquid is liquified gasses, mainly N2, O2, that were already in the balloon and he said that it was water, I wasn't going to argue but I still think he's full of crap.

Anyways, I don't want to lie to little kids, so who's right?
 
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You're correct, water would freeze. I'd guess it's primarily liquid oxygen since the oxygen liquifies at a temperature above that of LN2 at ambient pressure. Could be a bit of argon in there too. Water and carbon dioxide would solidify, and you could find them both in very small proportions compared to the oxygen.

Maybe get the liquid in there and put it over a burner at the end of a long stick? I bet the rubber in the balloon and concentrated oxygen would make an interesting, though small fireworks display!
 
Yes, it is liquid oxygen. If your balloon is clear, then the liquid should appear pale-blue. You should not attempt to burn it.
 

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