Vapor pressure experimental values, 7, Table

The triple points, boiling points, and critical constants for the isotopic forms of hydrogen and for several ortho-para concentrations are given in Table 2.4, and vapor pressure values are shown in Table 2,5. The vapor pressure equations of Table 2.5 agree with the experimental data for hydrogen to within the experimental error over most of the liquid range to the critical point. The values for deuterium and hydrogen deuteride should not be used at pressures much above atmospheric. 

Gee ° has applied this method to the determination of the interaction parameters xi for natural rubber in various solvents. Several rubber vulcanizates were used. The effective value of VelV for each was determined by measuring its extension under a fixed load when swollen in petroleum ether. Samples were then swollen to equilibrium in other solvents, and xi was calculated from the swelling ratio in each. The mean values of xi for the several vulcanizates in each solvent are presented in Table XXXVI, where they are compared with the xi s calculated (Eq. XII-30) from vapor pressure measurements on solutions of unvulcanized rubber in some of the same solvents. The agreement is by no means spectacular, though perhaps no worse than the experimental error in the vapor pressure method. 

A wide variety of solubilities (in units of g/m3 or the equivalent mg/L) have been reported. Experimental data have the method of determination indicated. In other compilations of data the reported value has merely been quoted from another secondary source. In some cases the value has been calculated. The abbreviations are generally self-explanatory and usually include two entries, the method of equilibration followed by the method of determination. From these values a single value is selected for inclusion in the summary data table. Vapor pressures and octanol-water partition coefficients are selected similarly. 

In the book, Vapor-Liquid Equilibrium Data Collection, Gmehling and colleagues (1981), nonlinear regression has been applied to develop several different vapor-liquid equilibria relations suitable for correlating numerous data systems. As an example, p versus xx data for the system water (1) and 1,4 dioxane (2) at 20.00°C are listed in Table El2.3. The Antoine equation coefficients for each component are also shown in Table E12.3. A12 and A21 were calculated by Gmehling and colleaques using the Nelder-Mead simplex method (see Section 6.1.4) to be 2.0656 and 1.6993, respectively. The vapor phase mole fractions, total pressure, and the deviation between predicted and experimental values of the total p... 

The thermodynamic constants of THF polymerization have been investigated by a number of authors. A variety of experimental techniques have been utilized including determinations of conversion to polymer, combustion, heat capacities eind vapor pressure. Comparison of our results with some previously published data shows that our results are within the range of the values reported (Table 3). 

The sorption data for tnethanol vapor and water vapor are given in Tables I and II, respectively. Column 7 of each table shows the calculated ratio of sorbed gas molecules to molecules of solid at a relative pressure, C = 1. These extrapolated values are deemed significant because they correlate with the chemical composition of the solid. Experimentally, the adsorption of water or methanol vapor is very low on hydrocarbons having polycyclic aromatic structures. For all substances listed, the ratio of sorbed gas to solid (molecular basis) is around 1 or higher except for Golden Yellow G.K. (0.25) and 1-aminoanthraquinone (0.04). Golden Yellow G.K. has a structure composed of... 

By comparing the second and third columns of Table V.l, it is seen that the agreement between the experimental and calculated water vapor pressure values is quite good. 

Table I lists experimental results, comprising derived values of the fugacity of benzene at known total molarity in the aqueous phase, [B], and known molarity of 1-hexadecylpyridinium chloride [CPC] or sodium dodecylsulfate [SDS]. Fugacities have been calculated from total pressures by subtracting the vapor pressure of the aqueous solution in the absence of benzene from the measured total pressure and correcting for the small extent of nonideality of the vapor phase (15, 22). Results are given for temperatures varying from 25 to 45°C for the CPC systems and 15 to 45°C for the SDS systems.

The experimentally determined activity coefficients, based on vapor pressure, freezing-point and electromotive force measurements, for a number of typical electrolytes of different valence types in aqueous solution at 25 , are represented in Fig. 49, in which the values of log / are plotted against the square-root of the ionic strength in these cases the solutions contained no other electrolyte than the one under consideration. Since the Debye-Htickel constant A for water at 25 is seen from Table XXXV to be 0.509, the limiting slopes of the plots in Fig. 49 should be equal to —0.509 the results to be expected theoretically, calculated in this manner, are shown by the dotted lines. It is evident that the experimental results approach the values required by the Debye-Hiickel limiting law as infinite dilution is attained. The influence of valence on the dependence of the activity coefficient on concentration is evidently in agreement with theoretical expectation. Another verification of the valence factor in the Debye-Hiickel equation will be given later (p. 177). 

Thus, the fugacity of species i (in both the hquid and vapor phases) is equal to the partial pressure of species i in the vapor phase. Its value increases from zero at infinite dilution (jc, = y, -> 0) to Pj for pnre species i. This is illnstrated by the data of Table 12.1 for the methyl ethyl ketone(l)/toluene(2) system at 323.15 K (50°C). The first tlnee columns list a set of experimental P-x -y data and colunms 4 and 5 show ... 

You can find experimental values of latent heats in the references in Table 4.5, and a brief tabulation is listed in Appendix D. The symbols used for latent heat changes vary, but you usually find one or more of the following employed AH, L, A, A. Keep in mind that the enthalpy changes for vaporization given in the steam tables are for water under its vapor pressure at the indicated temperature. 

Physical and Chemical Properties. More experimental and estimated data on the physical and chemical properties for 2,4-DNP are available than for other dinitrophenols (see Table 3-2). Even in the case of 2,4-DNP, reliable experimental or estimated values are not available for vapor pressure, Henry s law constant, and log K°<=. This is not surprising since dinitrophenols exist predominantly in the ionic forms at pH >6 with very low vapor pressure. If available, the physical constants are important in predicting the environmental transport of dinitrophenols. Therefore, it would be helpful to develop more reliable data on certain physical properties important in predicting the environmental fate of these compounds. 

We have applied the model over an extended range of external conditions from the triple point up to the critical point of water. Figure 2.24 compares the experimental " (steam tables) vapor pressures with the calculated ones. The two sets of values are practically identical. Figure 2.25 compares the corresponding values for the orthobaric densities of water. As observed, the density is well described over the full range. 

The NIST s Thermodynamics Research Center (TRC) has a large collection of pure-fluid thermodynamic and transport properties tables of recommended values and correlations exist both in paper form and in a computer database [12], The TRC has also produced books with comprehensive compilations for organic compounds (sometimes also available as software) for vapor pressure [17], liquid density [18], and ideal-gas heat capacity [29], in addition to a compilation on virial coefficients [32]. Their major archival database of experimental pure-component and mixture data is called Source [97] it is currently available only to members of their consortium. Some data for mixtures of organic compounds are published in the periodical Selected Data on Mixtures [49]. More information is at http //trc.nist.gov. 

Methanol in Hydrocarbon-Rich Vapor and Liquid. The volumetric properties of methanol gas (12) and the second virial cross coefficients of methanol and light gases (13) were used to determine the pure-component parameters AP(TC) and a for methanol. Table II shows the enthalpy departure of gaseous methanol from ideal gas at three temperatures and several pressures. For comparison, the experimental values (14) and the values calculated by the Soave equation (1) are also shown. Table II indicates that the Won modified equation of state predicts the enthalpy departure of methanol very well at low temperatures and fairly well at high temperatures, but that the original Soave equation considerably underestimates the enthalpy departure at all temperatures and pressures. Since the original Soave equation was meant to be applied only to hydrocarbons, we are not surprised at this result. Comparison of calculated and experimental second virial cross coefficients between methanol and methane (and also C02) is presented elsewhere (15).)... 

The enthalpies of vaporization, AHv, at selected temperatures have been calculated using the residual enthalpy data in Table II. These are compared with the ASHRAE values (10) in Table V. The uncertainty in our calculated values is estimated to be zb 0.2 kj mol"1 at lower temperatures increasing to zb 1.0 kj mol 1 near the critical. The Affv value at 239.67 K (bp 1.01325) calculated from the Clapeyron equation, the vapor pressure data, and the compression data is 20.12 kj mol"1. This value is designated as the experimental (expt.) value in Table V. The... 

The values in this table were measured either by calorimetric techniques or by application of the Claperyon equation to the variation of vapor pressure with temperature. See Reference 1 for a discussion of the accuracy of different experimental techniques and methods of estimating enthalpy of vaporization at other temperatures. Several of the references present empirical techniques for correlating enthalpy of vaporization with molecular structure. 

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