"Tom MacIntyre" wrote in
message ...
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.

Strictly speaking, the change of state occurs as the
latent heat is transferred, not after.

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.

If you peruse the phase space of water at
http://www.lsbu.ac.uk/water/phase.html
you will see that there is no liquid/vapor boundary
at 0 oC. At a range of pressure well below standard
atmospheric, it could happen near 0.01 oC.

John's challenge is a bit of a trick and appears
to show he knows how to read that graph and
accompanying table.

--
--Larry Brasfield
email:
Above views may belong only to me.