Someone can correct me if I am wrong, but here is what I think I know :
(1) I am unaware that any official organization like IUPAP, IUPAC, ACS, or
APS has ever made any "ruling" on this. Therefore, the situation could be
characterized as somewhat of a free-for-all. If someone can point to a
document that shows one of these organizations has made a ruling, please
point it out because I cannot find it.
(2) There have always been mavericks in both chemistry and physics who have
done things opposite to most. But I would have to say the physical chemists
have done the best job of trying to end this free-for-all. The changeover
from delta-U = Q - W to delta-U = Q + W started in chemistry clear back in
the 1960s, and I believe that change is complete. The ACS standardized
exams use +W, the GRE exams assume that, and I think every physical
chemistry text on my shelf uses +W.
(3) Some physics books have switched to +W but many still use -W.
So this leaves us in the position of disagreement within physics. And those
who are opposite the chemists are definitely outnumbered because physicists
in general are outnumbered by chemists in general. Many more students take
thermodynamics as part of physical chemistry than take it as a physics
course. So how would you write standardized exams if you were in charge? I
would certainly use +W because it seems clear to me this is the way the bulk
of students are being taught today, and I believe the majority is
substantial.
My Ph.D. is chemical-physics and I have undergraduate majors in both physics
and chemistry. I have been exposed to both methods. I greatly prefer that
we characterize things as being done to the system rather than having some
things done to the system and some things done by the system. Having a
mixed view of "in/out" sometimes being +/- and sometimes being -/+ just
seems dumb to me, and it certainly confuses students. Yes, I know, it has
roots in heat engines, but heat engines no longer dominate thermodynamics...
so my advice is... get over it. Sorry to be obnoxious, but at some point
you have to acknowledge you are swimming upstream against a strong current.
I teach delta-U = Q + W and have been doing so for over 20 years. At my
college the "chemistry" thermo course and the "physics" thermo course are
combined and I teach it. It is cross listed as both CEM 326 and PHY 326
Thermodynamics. I prefer to use a physics book when I teach this course,
and I have not had difficulty finding a physics book that treats work the
same way as the chemists treat work. For a one-semester college course I
use Daniel Schroeder's "An Introduction to Thermal Physics" and I highly
recommend it.
Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817