Thermodynamic functions for the systems 1-butanol, 2-butanol,andt-butanol + cyclohexane

The following properties of mixtures of the butanols with cyclohexane were measured over the whole range of composition: 1-butanol+cyclohexane and 2-butanol+cyclohexane; excess enthalpies at 15, 25, 35 and 45°C, excess volumes at 25 and 45°C, activity coefficients and excess Gibbs free energies at 45°C. 2-Methylpropan-2-ol (tertiary butanol)+cyclohexane; excess enthalpies at 26, 35, and 45°C, excess volumes at 26 and 45°C, activity coefficients and excess Gibbs free energies at 45°C. From these data, activity coefficients at the temperatures of the excess enthalpy measurements below 45°C have been computed, as a source of test data for models of alcohol association through hydrogen bonding.     

Thermodynamics of binary mixtures: excess gibbs free energies of 1,2-Dibromoethane mixtures with benzene,cyclohexane, carbon tetrachloride and dioxane at 20°C

The excess Gibbs free energies of 1,2-dibromoethane mixtures with benzene, cyclohexane, carbon tetrachloride and dioxane have been determined by a static vapour pressure method at 20°C. The results have been analysed in the light of the current theories of solutions due to Prigogine and Flory. Both the theories fail to fit the results with useful accuracy.     

Liquid phase PVT data for binary mixtures of toluene with nitroethane and acetone,and benzene with acetonitrile,nitromethane, and ethanol

Liquid phase PVT data were obtained at 0°C, 45°C, and 90°C for pressures up to 217.7 atm for various binary mixtures of toulene—nitroethane, toluene—acetone, acetonitrile—benzene, nitromethane—benzane, and ethanol—benzene. Such data are required for purposes of converting excess thermodynamic property data from a constant pressure basis to a constant volume basis. Data are presebt for each pure component and for three separate mole fractions for each binary pair. Because benzene solidifies at 5.5°C, data for pure benzene are reported at 12°C rather than 0°C.     

Solubility of Anthracene in Binary Carbon Tetrachloride + Alkane Solvent Mixtures

Abstract

Experimental solubilities are reported for anthracene in binary solvent mixtures containing carbon tetrachloride with n-hexane, n-heptane, n-octane, cyclohexane, methylcyclohexane and isooctane at 25°C. Results of these measurements, combined with the excess Gibbs free energies of the binary solvents, are used to test predictive expressions derived from the nearly ideal binary solvent (NIBS) model. Expressions based on a volume fraction average of solute properties in the two pure solvents predict anthracene solubilities to within a maximum deviation of 4.5% and an overall average deviation of 1.8%.     

Ternary liquid—liquid equilibria for acetonitrile—ethanol—cyclohexane and acetonitrile—2-propanol—cyclohexane

Liquid—liquid equilibrium data were obtained for two ternary systems: acetonitrile— ethanol—cyclohexane at 40°C, and acetonitrile—2-propanol—cyclohexane at 50°C. Binary vapor—Liquid equilibrium data were measured for acetonitrile—2-propanol at 50°C. The binary parameters of the Zeta and effective Zeta equations were evaluated from equilibrium data for binary pairs. The parameters obtained were used to predict the ternary liquid—liquid equilibrium data for six systems involving the present systems and the ternary vapor—liquid equilibrium data for one completely miscible system and two partially miscible systems without adding any ternary parameter. A heterogeneous area calculated by the Zeta equation is in general too large and does not decrease appreciably with increasing values of the third parameter ζ of the Zeta equation. However, the effective Zeta equation works much better than the original Zeta equation in data reduction.     

Vapor–liquid equilibria of 2-butanol + aromatic hydrocarbons at 308.15 k

Vapor–liquid equilibria (VLE) data of 2-butanol?+?benzene or toluene or o- or m- or p-xylene measured by static method at 308.15?±?0.01?K over the entire composition range are reported. The excess molar Gibbs free energies of mixing (G ^E) for these binary systems have been calculated from total vapor pressure data using Barker's method. The G ^E for these binary systems are also analyzed in terms of the Mecke–Kempter type of association model with a Flory contribution term using two interaction parameters and it has been found that this model describes well the G ^E values of binary systems benzene or toluene.     

Thermochemical investigations of associated solutions. 13. Calculation of anthracene-chlorobutane association parameters from measured solubility data

Experimental solubilities are reported for anthracene dissolved in binary solvent mixtures containing 1-chlorobutane with n-hexane, n-heptane, n-octane, cyclohexane, methylcyclohexane and isooctane at 25°C. Results of these measurements, combined with estimates for the excess Gibbs free energy of the binary solvents, are used to evaluate the equilibrium constant for a presumed anthracene-chlorobutane molecular complex from the Extended Nearly Ideal Binary Solvent model. A single equilibrium constant was needed to describe the experimental data to within an average deviation of about 0.7%. The calculated association constant varied slightly with inert hydrocarbon cosolvent, the values ranging from K _AC ^ϕ =2.5 for isooctane to K _AC ^ϕ =6.0 for the cyclohexane cosolvent.     

Isobaric vapor–liquid equilibrium for methyltrichlorosilane–dimethyldichlorosilane–benzene system

Isobaric vapor–liquid equilibrium (VLE) for the system methyltrichlorosilane–dimethyldichlorosilane–benzene and that of the three binary systems were measured with a new pump-ebulliometer at the pressure of 101.325 kPa. These binary compositions of the equilibrium vapor were calculated according to the Q function of molar excess Gibbs energy by the indirect method and the resulted VLE data agreed well with the thermodynamic consistency. Moreover, the experimental data were correlated with the Wilson, NRTL, Margules and van Laar equations by means of the least-squares fit, the acquired optimal interaction parameters were fitted to experimental vapor–liquid equilibrium data for binary systems. The binary parameters of Wilson equation were also used to calculate the bubble point temperature and the vapor phase composition for the ternary mixtures without any additional adjustment. The predicted vapor–liquid equilibrium for the ternary system accorded well with the experimental results. The separation factor of methyltrichlorosilane against dimethyldichlorosilane in benzene was also reported. The VLE of binary and multilateral systems provided essential theory for the production of the halogenated silane.     

Correlation between excess adsorption data measured for solvent mixture/adsorbent systems and RM values obtained for different solutes chromatographed in binary mobile phases

This paper concerns the application of excess adsorption isotherms, measured for solvent mixture/adsorbent systems, to the characterization of TLC data. For this purpose the excess adsorption isotherms for three liquid mixtures: cyclohexane/ benzene, benzene/acetone, and carbon tetrachloride/ethyl acetate on silica gel at 20°C have been measured. These mixtures have been used as binary mobile phases in TLC measurements. It has been shown for a given solute in binary mobile phase that the quantity R_M is a simple function of the excess adsorption. Parameters of this function have been used to characterize chromatographic systems with binary mobile phases.     

Thermophysical properties of supercritical fluids with special consideration of aqueous systems

Selected thermophysical properties of polar, dense supercritical fluids are discussed. The static dielectric constant of water and the freon R22 (CHClF₂) is shown in some detail. Examples of critical curves for binary systems with water and methanol are given. New experimental data of excess volumes up to 400 °C and 2000 bar are shown for water combined with H₂, CH₄ and benzene. Excess Gibbs energies and activity coefficients for water-benzene are also shown. Results of the solubility of anthracene in ten different high pressure fluids, obtained by UV-spectroscopy, are presented. The PVT-data of concentrated supercritical aqueous NaCl-solutions and the ion product of pure water to 1000 °C are discussed.     

Boiling temperatures and excess thermodynamic functions of 2-propanol-n-alkyl propanoate solutions

Boiling temperatures of five binary systems are measured by ebuliometer in the pressure range of 5.333?C101.3 kPa. The compositions of equilibrium vapor phases in the systems are calculated using the constructed saturated vapor pressure isotherms as a base. The excess Gibbs energies, excess enthalpies, and excess entropies of solutions are calculated from our data on liquid-vapor equilibria. Regularities in the changes of phase equilibria and thermodynamic properties of solutions with the composition and temperature of the system are established. Vapor-liquid equilibria in the systems are described by the Wilson and NRTL equations.     

Total vapour pressure and excess Gibbs energy for binary mixtures of 1,1,2,2-tetrachlorethane or tetrachloroethene with cyclohexane at nine temperatures

Vapour pressures of (cyclohexane + 1,1,2,2-tetrachloroethane (TCANE)) or (cyclohexane + tetrachloroethene (TCENE)) mixtures at nine temperatures between 283.15 and 323.15 K were measured by a static method. The reduction of the vapour pressures to obtain activity coefficients and excess molar Gibbs energies was carried out by fitting the vapour-pressure data to the Redlich–Kister polynomial according to Barker’s method. A comparative analysis about the thermodynamic behaviour of both systems is performed, taking into account the resonance effect in tetrachloroethene. For 1,1,2,2-tetrachloroethane + cyclohexane mixtures, we have tested the DISQUAC model observing that reproduces satisfactorily the G^E experimental values at all temperatures.     

Solubility in Binary Solvent Systems: Comparison of Predictive Equations Derived from the NIBS Model

Abstract

Experimental solubilities are reported for pyrene in binary solvent mixtures containing benzene with n-hexane, cyclohexane, n-heptane, n-octane, cyclooctane and isooctane at 26°C. Results of these measurements, combined with published pyrene and biphenyl solubilities, are used to test predictive expressions derived from the Nearly Ideal Binary Solvent (NIBS) model. The most successful equation in terms of goodness of fit involved a surface fraction average of the excess Gibbs free energy relative to Raoult's law and predicted the experimental solubilities in 17 systems with an average deviation of 2.3% and a maximum deviation of 8.9%. Two expressions approximating weighting factors with molar volumes provided accurate predictions in many systems studied but failed in their ability to predict pyrene solubilities in solvent mixtures containing benzene.     

Excess magnitudes for the benzene + n-dodecane system at 298.15 and 323.15 K

The vapor pressures for benzene + n-dodecane mixtures have been measured using a static apparatus. Values for the excess Gibbs energy have been calculated using a modified form of Barker's method and fitted to a Padé approximant equation. Selection of the most adequate approximant is made according to objective criteria. The results are compared with those corresponding to other benzene + n-alkane systems. The values for the activity coefficient of benzene at infinite dilution calculated from these data agrees very well with the values obtained by gas-liquid chromatography.     

Vapour pressures and excess functions of N, N, N′, N′-tetramethylalkanediamine + cyclohexane. A group contribution study of the N---N proximity effect

The vapour pressuresof liquid cyclohexane + N, N, N′, N′-tetramethylalkanediamine, (CH₃)₂ N(CH₂)_uN(CH₃)₂ (u = 1,2) + cyclohexane mixtures were measured by a static method between 303.15 and 343.15 K at 10 K intervals. The excess molar enthalpies at 303.15 K were also measured.

The molar excess Gibbs energies, calculated from the vapour-liquid equilibrium data, and the molar excess enthalpies compare satisfactorily with group contribution (DISQUAC) predictions.

The proximity effect of N atoms produces a regular decrease of the interactional parameters.     

Untersuchungen über das Verhalten organischer Mischphasen 7. Mitteilung. Dampfdrücke,Dichten und thermodynamische Mischungsfunktionen des binären Systems Cyclohexan- Tetrahydrofuran bei 25°

The total vapor pressures and the heats of mixing of the system cyclohexane-tetrahydrofuran were measured at 25°C. The density was used to determine concentrations for the total pressure measurements. The partial pressures, activity coefficients, excess free energies, entropy functions, and excess volumes were calculated.     

Untersuchungen über das Verhalten organischer Mischphasen. 6. Mitteilung. Dampfdrücke,Dichten, thermodynamische Mischungsfunktionen und Brechungsindices des binären Systems Methanol-Diäthyl-äther bei 25°

The total vapor pressures, the heats of mixing, and the refractive indices of the system methanol-diethyl ether were measured at 25°C. The density was used to determine concentrations for the total pressure measurements. The partial pressures, activity coefficients, excess free energies, entropy functions, and excess volumes were calculated.     

Liquid-vapor equilibrium in the dimethyl sulfoxide-methanol system

The liquid-vapor phase equilibrium in the dimethyl sulfoxide-methanol binary system was studied with the use of a statistical method. Partial pressures of dimethyl sulfoxide and methanol were calculated by integrating the Gibbs-Duhem equation. Molar excess Gibbs energies were described by the Redlich-Kister equation, and correlation parameters were calculated. It was found that molar excess Gibbs energies are negative, and the deviation from ideality increases as temperature increases.     

Isobars of the boiling temperature and isotherms of excess thermodynamic functions of isobutanol-alkyl ketone solutions

The boiling temperatures for solutions of five binary systems are measured via ebulliometry in the pressure range of 5.333–101.3 kPa. The isotherms constructed for the pressure of saturated vapor serve as the base for computing the compositions of equilibrium vapor phases of the systems. The excess Gibbs energies, enthalpies, and entropies of solutions are computed from the data on liquid-vapor equilibrium. The laws of changes in the phase equilibria and thermodynamic properties of solutions are determined depending on the composition and temperature of the systems. The vapor-liquid equilibrium of the systems is described by Wilson and NRTL equations.