On Wed, 15 Jun 2005 23:37:49 GMT, Tom MacIntyre
wrote:

On Wed, 15 Jun 2005 18:01:25 -0500, John Fields
wrote:

On Tue, 14 Jun 2005 11:21:21 -0800, (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 boiling and freezing points are pressure dependent. Not only that,
a certain amount of heat must be lost or gained (latent heat, I
believe, is the term) before the change of state occurs.

---
At one atmosphere of pressure, the "latent heat of vaporization" of
water is 540 calories per gram and is the amount of heat required to
change liquid water at 100°C into steam at 100°C. That's used to
great advantage, in reverse, in steam heating systems where steam
which has been generated in a boiler is forced to condense into liquid
water in a remotely located radiator and release that heat into the
environment surrounding the radiator when it (the steam) changes
state.
---

I am simply
going by memory of my old Physics classes, and I have no idea what
pressure would be required to allow water to boil at 0 C. I think
other substances have boiled at lower temperatures than that at STP
though.

---
Yes. Liquefied gases, in particular, do that, and I'm anxiously
awaiting Floyd Davidson's response which will nail down the pressure
required to allow water to boil at 0°C.

--
John Fields
Professional Circuit Designer