Wednesday, February 18, 2009

General Science: Dry Ice

We started off the session by discussing what makes dry ice so COOL.

While it looks like regular water ice, it is actually frozen carbon dioxide. It is genuinely cooler than regular ice. That's why we ONLY handled the dry ice with tweezers. Possibly the coolest part is how it sublimes, meaning it changes directly from solid into a gas, skipping the liquid phase.

Then we demonstrated its coolness in the following ways....
  • froze cooked pasta and flowers by dropping them in acetone with dry ice. (Acetone is good thermal conductor, so it gets really really cold.)
  • produced a lot of spooky fog.
  • "poured" carbon dioxide gas into a cup on a scale and noted that it weighed more than an equal volume of air.
  • used carbon dioxide gas as a fire extinguisher (Don't panic, the fire was a single lit candle).
  • measured temperature changes in water after adding dry ice.
  • made the dry ice "squeal" and vibrate after pressing it with a metal spoon.
  • inflated a latex glove by putting a piece of dry ice inside and then tying off the open end.
  • produced a loud popping sound by placing a piece of dry ice in a small plastic container and then closing it.

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