Hmm, I guess I have to explain more carefully the nature of the exact system I have in mind. Work is done in a small (microscopic, if necessary) scale so that it is transferred directly as work to the internal energy of the system. The isothermality is taken care of by the reservoir and thus the...
Yes, in this kind of a situation it is true that the quasistatical limit cannot be reached: events that increase entropy are certainly present in the fluid. However, it should be noted that actually in any realistic process we cannot really reach the quasistatical conditions. Thus it is not a...
Turning a paddle can be done quasistatically by doing infinitesimal turns at a time. Thus the system is in equilibrium throughout the process and the equality dS = dQ/T is valid. It is important to recognize that the inequality dS \geq dQ/T (from which the other inequalities of thermodynamics...
You should note that the equality that I presented between entropy and free energy changes is exact so there is a direct connection (not inequality) between these changes. Also, the inequality between work and free energy is an equality for quasistatic processes. Therefore using the inequality...
I don't think the formula dF \leq dW - SdT should be restricted to some certain forms of work because the Helmholtz free energy has a definition independent of the concept of a canonical ensemble. I am more willing to think that when "pathological" forces are introduced, the connection with the...
Thanks for the reply. This would seem to be the case when work is applied by making volume changes but the situation can vary quite a bit depending on the method of applying work. A more elaborate example could be constructed with a sufficiently large box of water or some other viscous fluid in...
I have a question that has puzzled me during the last couple of days. Suppose that there is a system (e.g. a small box filled with gas) that is connected to a heat bath (much larger than the system) at a constant temperature T. The studied system and the heat bath are thought to be isolated from...