For nonideal vapor phase, corrections for nonideaUty should be included. [Pg.10]

Eor nonideal vapor-phase behavior, the fugacity coefficient for component i in the mixture must be determined [Pg.158]

Cases 3 and 4 show strong vapor-phase nonidealities as well. [Pg.122]

K VALUE FOR IDEAL LIQUID PHASE, NONIDEAL VAPOR PHASE 3.7 [Pg.104]

Thus at all pressures (low enough that nonideal vapor phase corrections can be ignored) we have Th2 =Ti2 = 0.03462 ym = 0.93075 [Pg.487]

In equation 21 the vapor phase is considered to be ideal, and all nonideality effects are attributed to the liquid-phase activity coefficient, y. For an ideal solution (7t = 1), equation 21 becomes Raoult s law for the partial pressure,, exerted by the liquid mixture [Pg.235]

NONIDEAL LIQUID MIXTURES 3.5 K VALUE FOR IDEAL LIQUID PHASE, NONIDEAL VAPOR PHASE 3.7 K VALUE FOR IDEAL VAPOR PHASE, NONIDEAL LIQUID PHASE 3.8 THERMODYNAMIC CONSISTENCY OF EXPERIMENTAL VAPOR-LIQUID EQUILIBRIUM DATA 3.8 ESTIMATING INFINITE-DILUTION ACTIVITY COEFFICIENTS 3.10 [Pg.104]

At low pressures, it is often permissible to neglect nonidealities of the vapor phase. If these nonidealities are not negligible, they can have the effect of introducing a nonrandom trend into the plotted residuals similar to that introduced by systematic error. Experience here has shown that application of vapor-phase corrections for nonidealities gives a better representation of the data by the model, oven when these corrections [Pg.106]

As discussed in Chapter 3, the virial equation is suitable for describing vapor-phase nonidealities of nonassociating (or weakly associating) fluids at moderate densities. Equation (1) gives the second virial coefficient which is used directly in Equation (3-lOb) to calculate the fugacity coefficients. [Pg.133]

Conclusion Effect of Independent Variables on Vapor-Phase Nonideality [Pg.37]

As discussed in Chapter 3, at moderate pressures, vapor-phase nonideality is usually small in comparison to liquid-phase nonideality. However, when associating carboxylic acids are present, vapor-phase nonideality may dominate. These acids dimerize appreciably in the vapor phase even at low pressures fugacity coefficients are well removed from unity. To illustrate. Figures 8 and 9 show observed and calculated vapor-liquid equilibria for two systems containing an associating component. [Pg.51]

We proceed now with a discussion of the more general case nonideal liquid and nonideal vapor phases. Notice that the type of calculation involved depends on the information given, as described in Table 13.1. [Pg.483]

It is, of course, possible to derive equations analogous to Eqs. 10.2-17 and 10,2-18 for a nonideal vapor phase. [Pg.542]

The values of yx and y2 calculated in parts a) and b) differ by less than 1%. Therefore, the effects of vapor-phase nonidealities is here minimal. [Pg.538]

Example 6.5 Repeat the calculations from Example 6.4 taking into account vapor-phase nonideality. Fugacity coefficients can be calculated from the Peng-Robinson Equation of State (see Poling, Prausnitz and O Connell6 and Chapter 4). [Pg.107]

VPLQFT is a computer program for correlating binary vapor-liquid equilibrium (VLE) data at low to moderate pressures. For such binary mixtures, the truncated virial equation of state is used to correct for vapor-phase nonidealities, except for mixtures containing organic acids where the "chemical" theory is used. The Hayden-0 Connell (1975) correlation gives either the second virial coefficients or the dimerization equilibrium constants, as required. [Pg.211]

Pure-component vapor pressure can be used for predicting solubilities for systems in which Raoult s law is valid. For such systems pA = p°Axa, where p°A is the pure-component vapor pressure of the solute and pA is its partial pressure. Extreme care should be exercised when using pure-component vapor pressures to predict gas absorption behavior. Both vapor-phase and liquid-phase nonidealities can cause significant deviations from Raoult s law, and this is often the reason particular solvents are used, i.e., because they have special affinity for particular solutes. The book by Poling, Prausnitz, and O Connell (op. cit.) provides an excellent discussion of the conditions where Raoult s law is valid. Vapor-pressure data are available in Sec. 3 for a variety of materials. [Pg.9]

Since pf is a function of temperature, the dewpoint and bubble-point temperatures for an ideal vapor or liquid mixture can be determined as a function of the total pressure tr from Eq. (9) or (10), respectively. An analogous procedure can be used for real mixtures, but the nonidealities of the liquid and vapor phases must be accounted for. [Pg.229]

The method proposed in this monograph has a firm thermodynamic basis. For vapo/-liquid equilibria, the method may be used at low or moderate pressures commonly encountered in separation operations since vapor-phase nonidealities are taken into account. For liquid-liquid equilibria the effect of pressure is usually not important unless the pressure is very large or unless conditions are near the vapor-liquid critical region. [Pg.2]

This is a simple and important result. It equates VPIE to the isotopic difference of standard state free energies on phase change, plus a small correction for vapor phase nonideality, here approximated through the second virial coefficient. Therefore Equation 5.8 is limited to relatively low pressure. As T and P increase third and higher virial corrections may be needed, and at even higher pressures the virial expansion must be abandoned for a more accurate equation of state. [Pg.141]

This chapter presents quantitative methods for calculation of enthalpies of vapor-phase and liquid-phase mixtures. These methods rely primarily on pure-component data, in particular ideal-vapor heat capacities and vapor-pressure data, both as functions of temperature. Vapor-phase corrections for nonideality are usually relatively small. Liquid-phase excess enthalpies are also usually not important. As indicated in Chapter 4, for mixtures containing noncondensable components, we restrict attention to liquid solutions which are dilute with respect to all noncondensable components. [Pg.93]

In systems that exhibit ideal liquid-phase behavior, the activity coefficients, Yi, are equal to unity and Eq. (13-124) simplifies to Raoult s law. For nonideal hquid-phase behavior, a system is said to show negative deviations from Raoult s law if Y < 1, and conversely, positive deviations from Raoult s law if Y > 1- In sufficiently nonide systems, the deviations may be so large the temperature-composition phase diagrams exhibit extrema, as own in each of the three parts of Fig. 13-57. At such maxima or minima, the equihbrium vapor and liqmd compositions are identical. Thus, [Pg.1293]

With flashes carried out along the appropriate thermodynamic paths, the formalism of Eqs. (6-139) through (6-143) applies to all homogeneous equihbrium compressible flows, including, for example, flashing flow, ideal gas flow, and nonideal gas flow. Equation (6-118), for example, is a special case of Eq. (6-141) where the quahty x = and the vapor phase is a perfect gas. [Pg.655]

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