Re: Isobaric expansion

[Leigh Palmer <palmer@SFU.CA>]

At 6:02 AM -0800 3/18/00, Glenn A. Carlson wrote:
> > Surely equilibrium thermodynamics
> > cannot be said to fail when applied to real thermodynamic processes.
> > If it isn't of any use in those cases then what is it good for?
>
> Equilibrium thermodynamics does fail when applied to real
> thermodynamic processes, but to different degrees.  Relatively slow
> processes (slow compared to the relaxation time of the system) are
> described very well by equilibrium thermodynamics.

One might say they are described perfectly well. If the "failures"
are not measurable in practice then they are not failures. Your
conception of ideality is that of a philosopher and not that of a
physicist.

> > Thermodynamic equilibrium states subsume static equilibrium states.
> > A box of gas in an unchanging state of thermodynamic equilibrium is
> > in static equilibrium by conventional definition.
>
> I'm curious, then.  How do you define "dynamic equilibrium"?  Is a
> reversible chemical reaction at equilibrium static or dynamic?

I believe that conventionally "equilibrium" in this context implies
"thermodynamic equilibrium". I can't recall using the term "dynamic
equilibrium". What does it mean? The term "static equilibrium", used
in mechanics, often pertains to systems in which motion is present.
It does not imply statsis, a point which must be made when teaching
the topic.

Leigh