Thermodynamics of binary mixtures containing aldehydes. excess enthalpies of n-alkanals + benzene and + tetrachloromethane mixtures

Molar excess enthalpies H^E have been measured as a function of mole fraction at atmospheric pressure and 298.15 K for the binary liquid mixtures of ethanal, propanal, butanal and pentanal + benzene or + tetrachloromethane. The results show that the excess enthalpies decrease with increasing the n-alkanal chain length, with negative values for n-pentanal.     

Excess Gibbs free energies and excess enthalpies for triethylamine + n-hexane,triethylamine + n-octane,and tributylamine + n-hexane at 298.15 K

Total vapour pressures have been measured by the isoteniscope method for triethylamine + n-hexane, triethylamine + n-octane, and tributylamine + n-hexane at 298.15 K. The excess Gibbs free energies G^E for the liquid phase have been calculated from the measurements; G^E is positive for the triethylamine systems and negative for the tributylamine system. The excess enthalpies H^E for these three mixtures and for tributylamine + n-octane have been measured at the same temperature. Except for tributylamine + n-hexane, all these H^E's are positive.     

Thermodynamic properties of binary mixtures containing aldehydes. II. Liquid-vapor equilibria in normal or branched alkanal + normal alkane mixtures: Analysis in terms of a quasichemical group-contribution model

Recent liquid-vapor equilibrium data for three alkanal + n-alkane mixtures are examined on the basis of the surface-interaction version of the quasichemical group-contribution theory used in Part I to correlate and predict excess enthalpies and excess Gibbs energies for such mixtures. The predictions prove to be accurate to better than 10%. Using the new data, revised interaction parameters are proposed for the estimation of liquid-vapor equilibrium for normal or branched alkanal + normal alkane mixtures.     

p, T, x, y data of benzene + n-hexane and cyclohexane + n-heptane systems

The isothermal vapour—liquid equilibria of the benzene + n-hexane and cyclohexane + n-heptane systems have been studied using a dynamic method. The thermodynamic consistency of the data has been tested and the prediction from several empirical and semitheoretical models have been compared with the experimental values of different excess properties.     

Investigation of the surface tension of methane and n-alkane mixtures by perturbed-chain statistical associating fluid theory combined with density-gradient theory

The perturbed-chain statistical associating fluid theory (PC-SAFT) and density-gradient theory are used to construct an equation of state to describe the phase behavior of binary methane–n-alkane mixtures. With the molecular parameters and influence parameters regressed from bulk properties and surface tensions of pure fluids, respectively as input, both the bulk and interfacial properties are investigated. The surface tension of the binary systems methane–propane, methane–pentane, methane–heptane and methane–decane are predicted, and the results are satisfactory compared with the experimental data. Our results show that PC-SAFT combined with density-gradient theory is able to describe the interfacial properties of binary methane–n-alkane mixtures in wide temperature and pressure ranges, and illustrate the influence of the equilibrium bulk properties and chain length of n-alkane molecule on the interfacial properties.     

Excess enthalpies of the ternary mixtures: tetrahydrofuran + (diisopropyl ether or 2-methyltetrahydrofuran) + n-heptane at 298.15 K

Excess molar enthalpies, measured at 298.15 K in a flow microcalorimeter, are reported for the ternary mixtures (tetrahydrofuran + diisopropyl ether + n-heptane) and (tetrahydrofuran + 2-methyltetrahydrofuran + n-heptane). Smooth representations of the results are described and used to construct constant excess molar enthalpy contours on Roozeboom diagrams. The latter are compared with diagrams obtained when the model of Liebermann and Fried is used to estimate the excess enthalpies of the ternary mixtures from the physical properties of the components and their binary mixtures.     

Gas-liquid equilibria in nitrogen + n-hexadecane mixtures at elevated temperatures and pressures

Gas-liquid equilibrium in the temperature range 463–703 K in nitrogen + n-hexadecane mixtures was determined by a flow method. At each temperature, measurements were made at pressures from 20 to 255 bar or to near the critical pressure of the mixture.     

Excess volumes of binary mixtures of (p-xylene+an n-alkane)

A semi-continuous dilatometer for measuring excess volume is described. Excess volumes of p-xylene +n-hexane + n-octane, +n-decane, +n-dodecane, +n-tetradecane, and +n-hexadecane have been measured at 298.15 K as a function of composition.     

Vapour-liquid equilibria. I. An apparatus for isothermal total vapour pressure measurements: Binary mixtures of ethanol and t-butanol with n-hexane, n-heptane and n-octane at 313.15 K

A static apparatus for the determination of total vapour pressure isotherms of mixtures is described. The apparatus works without a null manometer, and degassing of samples is done without freezing. VLE data for six binary mixtures of ethanol and t-butanol with n-hexane, n-heptane and n-octane are reported and compared with literature data. References to other VLE data obtained using this apparatus are also given.     

Isothermal measurements of vapor-liquid equilibria for three n-alkane-chloroalkane mixtures

Results of isothermal vapor-liquid equilibrium (VLE) measurements for 1-chlorobutane with n-hexane and n-heptane at three temperatures and for 1,2-dichloroethane with n-heptane at two temperatures are reported.New constants of the Antoine vapor pressure equation for 1,2-dichloroethane are presented. The consistency of the new vapor-pressure data with published experimental data of heat of vaporization is checked.The VLE data are used for the determination of group interaction parameters of UNIFAC and of the quasichemical group surface interaction model (QUAGSIM).     

The thermodynamics of a cycloalkane + an n-alkane

The excess volumes of cyclopentane + n-hexane, + n-heptane, n-dodecane; cyclohexane + n-pentane; cycloheptane+ n-pentane, n-octane and n-dodecane have been measured at two temperatures. The results together with literature values reported for other systems of the type cycloalkane + an n-alkane have been discussed and the trends highlighted.V^E_m and H^E_m results from our work and from the literature, for the systems cyclopentane or cyclohexane + an n-alkane, have been analysed in the light of the statistical theory of Flory.     

Measurements of vapour-liquid equilibria,densities, viscosities and dielectric properties of cyclohexanone + triethylamine mixtures with respect to keto-enol tautomerism

Densities, ?, kinematic viscosities ν, refractive indices n_D referred to the sodium D-line, static relative permittivities ε, specific conductances κ and vapour-liquid equilibrium data for cyclohexanone + triethylamine mixtures have been determined at two temperatures. Excess properties of mixing calculated from these data indicate that in such mixtures considerable amounts of enol-amine associates are formed. The permittivity data indicate that the formation of associates is an exothermic process, which also has a marked influence on the thermodynamic excess properties of the mixtures. The enol-amine associates may undergo electrolytic dissociation. A common evaluation of static relative permittivities and specific conductances shows that for the mixture the conductance data are affected considerably by the formation of undissociated ion pairs in the sense of Bjerrum theory, especially at concentrations of the mixture where it is less polar. The conductance data are also influenced considerably by the fact that the ion pairs are solvated if the molar ratio of triethylamine exceeds 0.5.     

Phase equilibria for binary n-alkanenitrile—n-alkane mixtures. I. Upper liquid—liquid coexistence temperatures for ethanenitrile,propanenitrile, and n-butanenitrile with some C5C18n-alkanes

The upper critical solution temperatures (UCST's) of 26 n-alkanenitrile—n-alkane mixtures containing CH₃CN, C₂H₅CN, and C₃H₇CN with C₅C₁₈n-alkanes have been estimated experimentally. The UCST's diminish with increasing nitrile chain length and increase with increasing alkene chain length. The results are described well by the Weimer—Prausnitz modification of the regular solution theory incorporating a Flory—Huggins entropy of mixing.     

Excess heat capacities of binary mixtures of carbon tetrachloride with n-alkanes at 298.15 K

A Picker flow microcalorimeter was used to determine molar excess heat capacities C_P^E at 298.15 K for mixtures of carbon tetrachloride + n-heptane, n-nonane, and n-decane. The excess heat capacities are negative in all cases. The absolute value |C_P^E| increases with increasing chain length of the alkane. A formal interchange parameter, c_P12, is calculated and its dependence on n-alkane chain length is discussed briefly in terms of molecular orientations.     

The effect of keto-enol tautomerism on the properties of methylethylketone + benzene mixtures

Ratkovics, F. and Palágyi-Fényes, B., 1984. The effect of keto-enol tautomerism on the properties of methylethylketone + benzene mixtures. Fluid Phase Equilibria, 16: 99–116.The density, viscosity, static relative permittivity, conductivity and refractive index of methylethylketone + benzene mixtures have been measured in the interval 293.15–313.15 K. Vapor-liquid equilibrium data for the same mixtures were measured between 313.15 and 333.15 K. The results obtained indicate the formation of an association complex between benzene and methylethylketone in the enolic form, and the keto-enol equilibrium is shifted accordingly towards formation of the latter. Electrolytic dissociation of the benzene-enol association complex contributes to the conductivity of the benzene-ketone mixtures. In addition to concentration, the relative permittivity also has a considerable influence on the conductivity, since a considerable number of nondissociated ion pairs are formed (in the sense of Bjerrum theory). Comparison of the model based on the physical picture outlined and the experimental results indicates that ions deriving from the benzene-enol association complex are solvated in the region of higher benzene molar ratios. The model is also suitable for the interpretation of results obtained for mixtures containing other ketones and proton acceptors.