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Re: vapor



Joseph E Sabol wrote:

I think the "experts" should call it water gas phase.

I don't see why they should.

I'm quite sure they don't.

Communication requires using words the way other people use them.




Robert Cohen wrote:

It seems to me that "vapor" is the accepted term.

Yes, the gaseous phase of H2O is called water vapor. Maybe
there are exceptions, but I can't think of any.

Personally, I blame phase diagrams for part of the problem. I think they
confuse students. Students don't realize what the P refers to (it is
pressure of the substance at equilibrium, no?)

P means pressure. I don't see what's confusing about that.

The whole phase diagram presupposes equilibrium. I don't
see what's confusing about that.

and end up thinking that the
gas phase of water cannot exist below 100C

Huh? Everyday experience with atmospheric humidity should
give the students plenty of intuition about water vapor
below 100C.

or that gas and liquid water
cannot coexist except in rare circumstances.

Huh? The most prominent thing on the phase diagram is
the coexistence curve. I don't see how that causes students
to think there is no coexistence.

What are the symptoms of confusion, and what's the evidence
that phase diagrams are to blame?