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View Full Version : What is Maxwell's Principle (Thermodynamics)?


FaNgS
Dec19-11, 01:01 AM
1. The problem statement, all variables and given/known data

I'm trying to calculate the saturation pressure and the densities of a liquid and vapor using an equation of state. I figured out how to do it and know how to proceed except that I don't understand Maxwell's Principle which is stated in number 2 below.


2. Relevant equations

∫P.dV - Psat (Vg - Vl) = 0
integration limits of the ∫P.dV are from Vl to Vg

Where P is the pressure,
Psat is the saturation pressure,
Vg is the gas volume,
Vl is the liquid volume

3. The attempt at a solution

I don't understand how principle is derived. The only equation which comes to mind that relates Pressure and Saturation Pressure is Raoult's Law which is y*P=x*Psat (y is the gas mole fraction and x is the liquid mole fraction).

I would also appreciate it if I can be guided to some references which explains this prinicple, the book lacks this principle.