Vapor-Pressure Equation Constants

Source From Smith, J. M., H. C. van Ness, and M. M. Abbot, Introduction to Chemical Engineering Thermodynamics, ed. 5. New York McGraw-Hill (1996). Reproduced with permission of the McGraw-HiU Companies. 

B are not changed. We also see it with Inp instead of logp and with p expressed in psia, bar, or atm. Changing from one of those forms to the other requires simple multiplication of A and B by suitable constants. 

Source. These values are taken from a variety of sources. Longer lists are in Dean, J. A. Lange s Handbook of Chemistry, ed. 12. New York. McGraw-HiU, pp. 10-29 to 10-54 (1979) Reid, R. C., J. M. Prausnitz, andT. K. Sherwood. The Properties of Liquids and Gases, ed. 3. New York McGraw-HiU, Appendix A (1977) and Lide, D. R., ed. CRC Handbook of Chemistry and Physics, ed. 71. Boca Raton, FL CRC Press, pp. 6-70 (1990). 

To make life hard for the student and the working engineer, Henry s law is expressed in a variety of ways, with a variety of dimensions. We can rewrite Eq. 3.6 as 

FUGACITY COEFFICIENT CHARTS 307 Chemists regularly write Henry s law as 

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Table 1. Vapor-Pressure Equation Constants for the Butanes, Butylenes, and Butadienes ...

Butadiene, 4 365 physical properties of, 4 367 vapor pressure equation constants,... 

Vapor pressure equation constants can be found in Appendix A. Calculate the dimerization and tetramerization constant of acetic acid using the parameters given in Table 13.6. 

Third and Fourth cards FORMAT(3E20.14), constants for zero-pressure reference fugacity equation, vapor pressure equation, or hypothetical-liquid reference fugacity equation of the form... 

ASSOCIATION AND SOLVATION PARAMETERS CONSTANTS FOR ZERO PRESSURE PEFEPENCE FUGACITY EQUATION IF IVAP.EQ.I OR CONSTANTS FOR VAPOR PRESSURE EQUATION IF IVAP.GT.I... 

For any industrial process involving vapors and Hquids, the most important physical property is the vapor pressure. Table 1 presents values for the constants for a vapor-pressure equation and the temperature range over which the equation is vaHd for each butylene. 

Reported vapor pressures and Henry s law constants of ethylcyclohexane at various temperatures and the coefficients for the vapor pressure equations... 

The printed data output step 4 lists the values for the constants A and B of the general vapor pressure equation and the enthalpy and entropy of vaporization or sublimation. 

Recently, Tang and Munkelwitz (1991) applied a variation on this theme by determining very low vapor pressures of levitated droplets from data obtained at atmospheric pressure and in an evacuated chamber. In both cases they used data from the literature obtained at temperatures much higher than room temperature together with their new data to fit the constants in vapor pressure equations of the form... 

A, B, C Constants of the Antoine vapor pressure equation below 30-mm. pressure, covering the temperature range as indicated. See method of obtaining the constants on page 6. 

The introduction of a third constant C leads to an improved equation which has been tested in some detail and found to be the best three-parameter vapor pressure equation for general use.1-2 Usually the temperature term in Eq. (4) is in degrees Celsius. Because of its simple form and generally good accuracy, this equation has been chosen for use in some of the most extensive compilations of... 

To find the correct vapor pressure equation, we shall determine the variation of latent heat with temperature. In introducing the enthalpy H = U + PV in Chap. II, we saw that the change in enthalpy in any process ( quailed the heat absorbed at constant pressure. Now the latent heat is absorbed at constant pressure therefore it equals the change of the enthalpy between solid and gas. That is,... 

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