"keith" wrote in message
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On Thu, 16 Jun 2005 14:08:59 -0800, Floyd L. Davidson wrote:

Winfield Hill -edu wrote:
John Fields wrote...
Floyd L. Davidson wrote:
John Fields wrote:
Floyd L. Davidson wrote:

The idea that water boils at 100C and freezes at 0C, without
some mention of pressure, has little meaning. Water can "boil"
at 0C too.

Since, by your own admission, the boiling and freezing point
temperatures of water are pressure dependent, I invite you to state
what pressure would be required to be exerted on a volume of liquid
water in order to cause it to boil at 0°C.

The answer of course is: not much.

Hmmm...

Same as the answer to: "What does Floyd L. Davidson know about
anything?".

He appears to be confusing sublimation and evaporation with boiling.

*Look* at the statement:

Water can "boil" at 0C too.

It is *correct*, as you've all been very hasty to demonstrate.
It is not so precise as to say "at 0.010C", but certainly that
value is well within the normal meaning of "0C" (what, -.5 to
+.5 C!).

Huh? The issue is not whether water can be a gas at 0C, rather can it
*boil*. Since there is nowhere in the phase diagram that the water and
gas phase touch each other at 0C, my guess is that it cannot boil at
0C, at *any* pressure. It's only a guess though. ;-)


What a lot of you are missing though is that the diagrams you are looking at
are equilibrium states. Take a large quantitiy of liquid water at 0.05 C
and let it stand. Now, have it in a chamber at something like 1 kPa. Next,
*rapidly* reduce the pressure on the surface (maybe suddenly open it to a
large vacumn chamber). You can then get evaporation to cool the liquid and
at the same time get some of the water to violently change phase to a gas
(i.e. 'boil'). You will also get a far amount of ice formation as the
latent heat of vaporization is supplied by fusing some of the water into
ice.

Of course, this is only a transitory phenomenon, but it is 'boiling'

daestrom