S as function of V and T. For simplicity, we consider first a pure phase component i. Integration of (91) yields
(107)
Expansion in an ideal gas and a deviation term:
(108)
Solving the last integral in (108):
(109)
Extending the lower integration limit:
(110)
The first two terms of (110) are the S of an pure hypothetical ideal gas. If the system is a mixture ideal mixing entropy has to be added
(111)
