On 16 Jun 2005 04:16:54 -0700 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.

No, it sounds to me like he knows his phase diagrams. Water can indeed
be made to both boil and freeze (simultaneously) near 0C if the
pressure is appropriately low. I don't recall the exact pressure, but
it's a medium vacuum (1 Torr, 50 Microns,... ???) That combination of
temperature and pressure is called the triple point of water because
all 3 phases of water exist in equilibrium there. It is a fundamental
property of water that can be used to calibrate thermometers.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------