Re: vapor versus gas

[Norman Lohstreter <petel@TENET.EDU>]

A nifty demonstration of Liquid CO2 is to cut the narrow end off of a
plastic (beral) pipette and place some dry ice in the bulb portion.
Fold the open end over several times and clamp it together with a pair
of pliers.  Place the bulb/dry ice end in some room temp. water and soon
the solid will melt and liquid CO2 is visible in the bulb.  More often
than not, the pressure is enough to rupture the bulb with quite a
startling effect.  The effect is even more exciting if the bulb is still
in the water. ;-)

Leigh Palmer wrote:
> 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

--
Pete Lohstreter                         "Reality is merely an illusion,
The Hockaday School                     albeit a very persistent one."
Dallas, TX 75229                                           A. Einstein
petel@tenet.edu
http://www.hockaday.org
http://home.hockaday.org/HockadayNet/academic/physics/