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Re: vapor versus gas



CO2 fire extinguishers do indeed contain liquid CO2 at room temperature.
Pick one up and you will be able to feel it sloshing about inside. You
won't be able to view this liquid because it is at a pressure (if my
quite fallible memory is correct) of about 40 atmospheres and putting
it in a glass tank would be quite dangerous. If you are permitted to do
so, discharge the extinguisher (the pure CO2 kind) and observe what
emerges - carefully. I use this as a demonstration in more than one of
my courses. I even use it as a demonstration in an introductory
astronomy course to give some idea of what is happening in the geysers
on Neptune's moon Triton.

"The" boiling point (should be "the normal boiling point") is the
temperature at which a substance undergoes the liquid-vapor change of
state at normal atmospheric pressure. The characteristic temperature
intrinsic to the substance itself is the critical temperature, not the
normal boiling point.

Leigh