Re: Entropy Change Problem

[David Bowman <dbowman@TIGER.GEORGETOWNCOLLEGE.EDU>]

Regarding my last post where I wrote:
> ...
> If you placed a mass of liquid water in thermal contact with only a
> surrounding gas and insulated the combined water/gas system from the
> rest of the universe after first requiring that the initial
> temperature of both the water and the gas was at the freezing point
> of the water, then you would find that the water *doesn't* freeze.
> It *stays* liquid.

I forgot to mention a point about the reverse process of the one that
Don P. described--the reverse process *is* spontaneous.  If you
started with a block of ice at the freezing point of water and
surrounded it with a gas that is at a higher temperature, and then
insulated the composite system the ice would begin to melt and the
gas' temperature would decline.  If there was too much ice the
melting process would stop when the gas temperature reached the
melting point of the ice.  If there was too much gas all the ice
would melt and the melted water and the gas would come to a common
temperature that was above the melting point of the ice.  If there
was just the right ratio between the masses of the gas and the ice
and the initial temperature of the gas was just right, then it
would be possible to have the last of the ice melt just when the
gas temperature reached the melting point.

David Bowman