I’ve been frustrated for 40 years that it has been hard to draw a T~S graph for a thermodynamic system undergoing a process, even if you know the P~V relationship in detail.
This is largely because those who claim to teach Thermo. to engineers usually don’t really understand it (I did my first degree at Imperial College…they were very poor teachers). There is a real fear of saying anything about absolute entropy (as opposed to entropy differences). This stems from a reluctance to address anything in statistical thermodynamics. Without understanding microstates, you can get nowhere with this problem.
Anyway, I now have a reliable way to plot a T~S graph for a known cycle in P~V space.This relies on the Sackur-Tetrode expression for the entropy of an ideal gas.
