Context: I'm studying basic thermodynamics. My textbook has a chapter on the Clapeyron equation which, as a reminder, is given by the following formula:
\begin{equation} \frac{dP}{dT} = \frac{\Delta H_{a,b}}{T\Delta V} \end{equation} (a,b being the different phases)
Question: The equation describes the tangents of the coexistence curves in $P,T$ diagrams, but why is it so important ?
- Does indeed encompass some fundamental thermodynamics knowledge in it (that I am obviously missing) and/or
- Is it useful at calculating thermodynamic properties of substances[*] and/or
- Has it been artificially emphasized in our course, so that it serves as a question in the exams?
Possible answer: I've found in my lecture notes that "Clapeyron equation is the most important experimental confirmation of the 2nd law of thermodynamics". How would you comment on that ?
[*] I watched an online MIT lecture on Clapeyron (that SE won't let me link) and it had a nice example with an hypothetical RDX explosive detector and the least number of molecules that should detect, based on the vapor pressure of RDX in room temperature.