Data for Mixtures

Phase equilibria are a fundamental basis of many steps in chemical processes. Quantitative knowledge of these equilibria and data on the substances involved are therefore a prerequisite for developing processes and designing apparatus [Gmehling 1992]. 

Vapor-liquid equilibria can easily be measured experimentally and described mathematically. Equation (3.3-1) is the general relationship for the equilibrium between a liquid phase and an ideal gas phase  

Yi mole fraction of component i in the gas phase mole fraction of component i in the liquid phase P°i(T) saturation pressure of pure component i at the system temperature T 

In the simplest case the vapor pressure of the pure components P can be expressed by the Clausius-Clapeyron equation  

Since the heat of evaporation AyH is not constant, in practice the three-parameter Antoine equation (3.3-3), which allows the vapor pressure to be accurately calculated even over large temperature ranges, is widely used  

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TABLE 5.2 Data for Mixture of Alkanes to Be Separated by Distillation... 

Mixtures. A number of mixtures of the hehum-group elements have been studied and their physical properties are found to show Httle deviation from ideal solution models. Data for mixtures of the hehum-group elements with each other and with other low molecular weight materials are available (68). A similar collection of gas—soHd data is also available (69). 

A key feature of this model is that no data for mixtures are required to apply the regular-solution equations because the solubiHty parameters are evaluated from pure-component data. Results based on these equations should be treated as only quaHtative. However, mixtures of nonpolar or slightly polar, nonassociating chemicals, can sometimes be modeled adequately (1,3,18). AppHcations of this model have been limited to hydrocarbons (qv) and a few gases associated with petroleum (qv) and natural gas (see Gas, natural) processiag, such as N2, H2, CO2, and H2S. Values for 5 and H can be found ia many references (1—3,7). 

De Lean, A., Hancock, A. A. and Lefkowitz, R. J. (1982). Validation and statistical analysis of a computer modeling method for quantitative analysis of radioligand binding data for mixtures of pharmacological receptor subtypes, Mol. Pharmacol., 21, 5-16. 

In this case data for mixtures of H2S+CO2+DIPA+H2O were used together with the data for H2S+DIPA+H2O and CO2+DIPA+H2O to obtain the interaction parameters and equilibrium constants. The results are shown in Figures 1 and 2 to be in good agreement with the experimental data ( 3). In this case, however, in contrast to the case of MEA, the predictions use parameters evaluated from data for the four component system. 

Design of extraction processes and equipment is based on mass transfer and thermodynamic data. Among such thermodynamic data, phase equilibrium data for mixtures, that is, the distribution of components between different phases, are among the most important. Equations for the calculations of phase equilibria can be used in process simulation programs like PROCESS and ASPEN. 

When assessing the risk associated with mixtures, oftentimes the data for mixtures are not available. Thus, some scholars have assessed the risk from the individual components and used those to estimate risk using the dose-additivity model (for systemic... 

Analysis of spectroscopic data for mixtures with background absorption... 

A recirculation apparatus for the determination of high pressure phase equilibrium data for mixtures of water, polar organic liquids and supercritical fluids was constructed and operated for binary and ternary systems with supercritical carbon dioxide. 

Sufficiently similar mixtures. Another approach is to use surrogate data on one whole mixture to conduct the risk assessment of another. This applies the concept of sufficient similarity, defined as 2 mixtures close in chemical composition where there are small differences in their components and in the proportions of their components. Key issues for similar mixtures include assessing the similarity of analytical chemistry and toxicological data for mixtures. In this case, an RfD, RfC, or slope factor could be calculated for the mixture of concern using data on a sufficiently similar mixture. This concept is also used in specific applications to groups of similar mixtures that are produced by similar processes, for example, the comparative potency method as applied to diesel exhaust emissions (Lewtas 1985,1988 Nesnow 1990). 

Because of the lack of experimental data for mixtures of H2S + COz, we must rely on predictions to see the effect of varying the composition on the hydrate forming conditions. Figure 5.2 shows the hydrate formation for binary mixtures of H2S and C02 as predicted by the... 

Prediction of Isobaric Vapor-Liquid Equilibrium Data for Mixtures of Water and Simple Alcohols... 

Fio. 24. Retention data for mixture of 13 substituted naphthalenes and 7 mobile phases from Fig. 23 B (hexane present in all 8 mobile phases). See Ref. 20 for details. Reprinted with permission from Glajch ei al. (20). 

A third compilation intended to be devoted to polymorphic materials is that of Kuhnert-Brandstatter (1971). The body of this book is an identification table for hot stage studies of pharmaceutical materials (see Sections 4.2 and 7.2), in which materials are arranged by increasing melting point, with eutectic data for mixtures with azobenzene and benzil. There is considerable descriptive detail on the melting behaviour and identification and description of polymorphic forms, albeit only microscopic determinations, for approximately 1000 pharmaceutically important... 

A low-temperature luminescence system with a pulsed-source luminescence spectrometer has been designed. " A method for the analysis of luminescence data for mixtures adsorbed on filter paper is also of interest. " Similar methodology is well suited to the examination of air pollution. "... 

The most accurate way to determine the density of a mixture of liquids or a solution of a solid in a liquid is from experimental data. Perry s Chemical Engineers Handbook provides data for mixtures and solutions of a number of substances on pp. 2-99 through 2-118 and lists additional sources of data on p. 2-99. 

Vapor-liquid equilibrium data for mixtures of acetone (A) and ethanol at 1 atm are given in the following table ... 

A4.3.10.1.2 If data for mixtures are not available, ingredient data should be provided. In determining incompatibility, consider the substances, containers and contaminants that the substance or mixture might be exposed to during transportation, storage and use. 

Table 1 Quantitation data for mixtures of neotame forms A and G...

Prepare an enthalpy-concentration chart for a, binary mixture given the enthalpy or heat capacity data for the pure components, the heat capacity data for mixtures at various concentrations, and the necessary heats of mixing at various concentrations. 

Table IV summarizes percent consumption of ethylene consequent upon reaction of the pure substrate and three of its mixtures with propane with six different ratios of N(4S). Table V summarizes analogous data for propane. The data for mixtures given in the two Tables are derived from the same sets of experiments. Table VI summarizes apparent relative specific rates of consumption, kr2H4/kc.,Hs These ratios were calculated by means of Equation 14, the expression which would be appropriate...

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. 

For, say, a ternary non-ideal mixture, activity-coefficient data must be available. In such a case, the result of Equation (8.9) can be multiplied by (l-EX (3lny, /dx, )) as in the Vignes equation (8.6). One should recognize, however, that activity-coefficient data for mixtures with more than two components are scarce the best source for such data is the Gmehling series [11]. 

P14.6 Given the following data for mixtures of jciH20 + Jt2CH3(CH2)2OH ... 

This method also produces vapor-liquid equilibrium data for mixtures. It is restricted to liquid samples,... 

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