Liquid, fugacity volume change

These changes result in improvement in the liquid molar volume while retaining the good representation of fugacity and energy functions of the liquid state for normal fluids. 

The equations derived in 30c, 30d thus also give the variation with pressure and temperature of the fugacity of a constituent of a liquid (or solid) solution. In equation (30.17), Vi is now the partial molar volume of the particular constituent in the solution, and in (30.21), i is the corresponding partial molar heat content. The numerator — fti thus represents the change in heat content, per mole, when the constituent is vaporized from the solution into a vacuum (cf. 29g), and so it is the ideal" heat of vaporization of the constituent i from the given solution, at the specified temperature and total pressure. 

At 25 C, the vapor pressure of water is 23.76 mm. and the specific volume of the vapor under these conditions is 43,400 cc. g. Calculate the free energy change for the transfer of 1 mole of water from liquid at 25 C to vapor at unit fugacity. What error is involved in treating the vapor as an ideal gas (cf. Exercise 9, Chapter X) ... 

Ccmments A pressure of lo bar corresponds to the hydrostatic pressure of approximately lo m of water and is produced by less than i% by mol of solute The calculation demonstrates that it takes a very small mole fraction of solute to produce a fairly large osmotic pressure. The result may seem counterintuitive, but it is just another manifestation of the fact the pressure has a small effect on liquid properties it takes a fairly large osmotic pressure to change the fugacity of the mixed solvent enough to make it equal to that of the pure solvent. The mathematical explanation is that the molar volume of liquids, which appears in the denominator of eq. is veiy small... 

The last term on the right-hand side is the Poynting correction from saturated liquid at P, P, to compressed liquid at P°, T°. Before that is the change from gas at P°, T°, to saturated vapor, and before that is the change from h5q)othetical ideal-gas state at P°, to real state at the same conditions. Accordingly, (f>° is the fugacity coefficient atf, T°, is the fugacity coefficient of saturated vapor, and Vl is the molar volume of the liquid. After... 

The fugacities in the vapor and liquid phases may be obtained from an EOS. Alternatively, an activity-coefficient model can be used to describe the liquid phase to estimate > f. However, as discussed in Chapter 1, activity coefficient models, in general, may not be suitable for reservoir fluids because they are based on the assumption of no change in volume due to mixing. At equilibrium, when liquid and solid phases are present. 

As can be seen from Eq. (14), the solubility of a solid in an SCE depends not only on solid-state parameters, such as sublimation pressure and molar volume V , but additionally on the fiigacity coefficient (]), . The fugacity coefficient is the supercritical analogue to the activity coefficient (5). The fugacity coefficient varies not only with the type of fluid but with temperature and pressure (53). Therefore, solubility of solids can be significantly influenced by changing the density of SCFs on alteration of temperature and/or pressure. The fugacity coefficient is the key variable that explains the different solubility of solids in SCFs compared with ordinary liquids. 

Determine the fugacity of pure liquid acetone at 100 bar and 382 K. The molar volume of the liquid is 73.4 cmVmol. You may assume Vj does not change with pressure. 

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