Fugacity generalized chart

Generalized charts are appHcable to a wide range of industrially important chemicals. Properties for which charts are available include all thermodynamic properties, eg, enthalpy, entropy, Gibbs energy and PVT data, compressibiUty factors, Hquid densities, fugacity coefficients, surface tensions, diffusivities, transport properties, and rate constants for chemical reactions. Charts and tables of compressibiHty factors vs reduced pressure and reduced temperature have been produced. Data is available in both tabular and graphical form (61—72). 

Another property which can be represented by generalized charts is fugacity, ( ). The fugacity of a substance can be regarded as a corrected vapor pressure. At low pressures (below atmospheric) the use of pressure in the place of fugacity leads to tittle error in calculations. The fugacity coefficient is defined by... 

The fugacity coefficients (f/P) for the various species may be determined from the generalized chart in Appendix B if one knows the reduced temperature and pressure corresponding to the species in question. Therefore,... 

Related Calculations. If experimental P-V-T data are available, either as an analytical expression or as tabular values, the fugacity coefficient may be calculated by integrating the data (numerically or otherwise) as shown in step 3 above. However, if such data are not available, use the generalized fugacity coefficient chart to estimate fugacity values. Refer to Hougen, Watson, and Ragatz [4] for deviation-correction terms for values of Zc above and below the standard value of 0.27. 

The calculation of fugacity coefficients and the use of generalized charts are discussed in the standard thermodynamics texts. If the fugacity coefficients are known then in the nonideal case we find that... 

Determine the equilibrium composition that is achieved at 300 bar and 700 K when the initial mole ratio of hydrogen to carbon monoxide is 2. You may use standard enthalpy and Gibbs free energy of formation data. For purposes of this problem you should not neglect the variation of the standard heat of reaction with temperature. You may assume ideal solution behavior but not ideal gas behavior. You may also use a generalized fugacity coefficient chart based on the principle of corresponding states as well as the heat capacity data listed below. 

Generalized chart for fugacity coefficients We can write relation [7.46] in the form ... 

Generalized fugacity coefficients of pure gases and liquids (Z = 0.27). (Reprinted from O. A. Hougen, K. M. Watson, and R. A. Ragatz, Chemical Process Principles Charts, 3rd ed. Copyright 1964. Reprinted by permission of John Wiley Sons, Inc.)... 

However, even at low partial pressures, carboxylic acids may be extensively dimerized in the vapour phase, and corrections are necessary at higher pressures the fugacities of components must be obtained from published data or by applying a fugacity coefficient , = //p, derived from a generalized or compound-specific chart.)... 

Fugacity coefficients define the deviation from non-ideal to ideal gas behavior and can be determined from generalized compressibility charts or from suitable equations of state [e.g., Soave-Redlich-Kwong, Eq. (6.11.61) for details see Soave (1972)] ... 

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