Re: Sometimes physics is fun

["John S. Denker" <jsd@AV8N.COM>]

On 10/28/2003 09:14 PM, Bernard Cleyet wrote:
> How about a change of state rocket.  e.g. pressurized liquid N2. or
> cappuccino steamer.

CO2 cylinders contain liquid CO2.  Always have.
So they are the canonical example of a change-of-state
propellant.  Overcooling can be a problem, if/when you
try to hurry things; the latent heat has to come from
somewhere.

Many other medium-sized molecules have been used as
propellants in spray cans.  Propane and butane, for
instance, boil at convenient P/T values.  And then
there is freon.

Pressurized liquid N2 anywhere near room temperature would
be quite a feat of pressurization.  Seems kinda impractical.