Chapter 6 : Solution Thermodynamics and Principles of Phase Equilibria
Section 11 : Expression for Fugacity of a Pure Liquid
On equating the last two equations:
(6.118)
Since Vi, the liquid–phase molar volume, is a relatively weak function of pressure at temperatures well below the critical temperature, one may approximate where, is the molar volume of the saturated liquid at the temperature of interest.
Using in the integrated form of eqn. 6.108 gives:
(6.119)
The exponential term on the left side of the last equation is known as a Poynting factor. It may be noted that the calculation of the term can be made using a suitable gaseous EOS suitable to the temperature T and pressure
Example 6.7
Estimate the fugacity of cyclopentane at 110 C and 275 bar. At 110 C the vapor pressure of cyclopentane is 5.267 bar. (Click for solution)
where, 
is the molar volume of the saturated liquid at the temperature of interest.
in the integrated form of eqn. 6.108 gives:
can be made using a suitable gaseous EOS suitable to the temperature T and pressure 