DRY ICE IS COOL!  (literally)

(Warning: you need oxygen to live, so don't stick your head in a bucket of these fumes!
CO2 is denser than normal air, so it sinks.  That's why it's in some fire extinguishers)

Dry ice, or solid CO2, sublimes directly into a gas at common room temperatures.
To find dry ice naturally, you'd have to go to another planet, like Mars.

Ever seen liquid CO2?  I didn't think so!
Well, if contained under enough pressure, you can actually see liquid CO2...

Here I put some dry ice into plastic tubing and clamped one end.  A pressure guage shows all 3 states ocurring at about 80psi.


MORE ABOUT STATES OF MATTER


This stuff is chilly!  How chilly? -78.5ºC  Brrrr!  Do not touch with bare skin for long!

Here's what dry ice in a pop bottle will do...

WARNING, BEING CARELESS WITH A POP BOTTLE UNDER PRESSURE
CAN LEAD TO DISASTEROUS RESULTS.  TREAT IT LIKE ANY EXPLOSIVE DEVICE!  I have heard students talk about "Works bombs", and I am surprised that I haven't heard of any of them getting hurt.
Do not do this at home!
For experiments with dry ice, click here.