Both Joel and Bob are wondering who agrees with whom at this point. For my
part, I don't know. It has been longer than 30msec and my poor senile brain
forgets who said what (including me<g>)
Let me make some statements and see if anyone agrees with them -- others
should add their own:
1) The First Law is dE=dbarQ + dbarW -- can I please write DQ and DW
--(sorry, Dan, I have trouble with W&Q -- I wish ASCII had a dbar)
2) DQ and DW are BOTH _work_!!!
3) DQ is not necessarily connected to temperature difference or to
microscopic activity. (The Joule experiments give rise to a DQ but have no
external dT and are clearly macroscopic.)
4) For an _irreversible_ process, it is difficult to see a difference
between DQ and DW
And for the First Law mox nix.
5) I am having trouble thinking of a variety of reversible processes so
let's go with the usual adiabatic cylinder on a hot plate and a
frictionless piston:
5a) If sand is dribbled on the piston, that contribution would be to DW
_NOT_ because it is a mechanical or macroscopic process, but because it
does not give rise to a change in the entropy. (See my web page for a
preliminary sketch of this calculation)
5b) If the knob on the hot plate is slowly turned. the plate _does_
contribute to the entropy so we call that contribution DQ. The molecules
of the plate surface do _work_ via collisions, but that work is in DQ.
6) If the process is _irreversible_, usually one can not clearly see what
DW or DQ is. If I smash the piston with a 4 ton rock for example.
7) The only way to calculate DQ for the irreversible process is to choose a
reversible process with the same end states as the irreversible one,
determine the end point entropy of that process and then calculate DQ=TdS.
8) In some cases dS might be determined from a carefully chosen DQ of the
reversible process, but that would be the same DQ for the irreversible
process and DW would be nil.
Now, Joel, Bob, do we agree with at least the above???
NB I have not used the evil four-lettered word above.