Fugacity coefficient chart

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.) 

Generalized fugacity coefficients of pure gases and liquids for a critical compressibility (Z ) of 0.27. The critical properties of most species of interest to students are normally readily available via a search of the Web or standard handbooks. The reduced pressures (P ) and 

Introduction to Chemical Engineering Kinetics and Reactor Design, Second Edition. Charles G. Hill, Jr. and Thatcher W. Root. 2014 John Wiley Sons, Inc. Published 2014 by John Wiley Sons, Inc. 

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Use only the following data and the fugacity coefficient chart. 

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 standard state of each species is taken as the pure material at unit fugacity. Use only the following critical properties, thermochemical data, and a fugacity coefficient chart. 

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. 

FUGACITY COEFFICIENT CHARTS 307 Chemists regularly write Henry s law as... 

The fugacity coefficient departure from nonideaHty in the vapor phase can be evaluated from equations of state or, for approximate work, from fugacity/compressibiHty estimation charts. References 11, 14, and 27 provide valuable insights into this matter. 

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,... 

Equations for fugacity coefficients are derived from equations of state or are approximated from activity coefficient charts as functions of reduced temperature and pressure. Table 13.1 includes them for the popular Soave equation of state. At pressures below 5-6 atm, the ratio of activity coefficients in Eq. (13.7) often is near unity. Then the VER becomes... 

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... 

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)] ... 

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

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