Excess volumes,enthalpies, and Gibbs free energies for mixtures of benzene + p-xylene

Excess thermodynamic properties of benzene + p-xylene have been obtained at 288.15, 298.15, and 313.15 K. V^E was obtained with a Sodev vibrating-tube densimeter, H^E with a Picker flow microcalorimeter, and G^E was calculated from solid + liquid phase equilibria measurements. Measurements were also made of the heat capacity of liquid p-xylene as a function of temperature using the heat-capacity unit of the Picker flow microcalorimeter.     

Phase behaviour of binary n-alkanenitrile and n-alkane,and nitromethane and alkane mixtures

Upper critical solution temperatures of nitromethane and alkanes, and alkanenitriles and alkanes have been used to obtain a parameter, ψ, characterising the interaction between the pairs of unlike molecules in the mixture. Values of ψ have been calculated using a “hard sphere and attractive force” equation of state together with the van der Waal's one fluid model.Values of ψ obtained for the ethanenitrile and alkane mixtures have been compared with those obtained from an analysis of gas—liquid critical temperatures. There is a discrepancy of several percent between the values calculated from the two properties.     

Excess volumes for trichloroethene + benzene, + toluene, + p-xylene, + tetrachloromethane,and + trichloromethane at 303.15 K

Excess volumes V^E for trichloroethene (CCl₂CHCl) + benzene, + toluene, + p-xylene, + tetrachloromethane, and + trichloromethane have been measured at 303.15 K, by direct dilatometry. V^E has been found to be positive for trichloroethene + benzene, and + trichloromethane, and negative for trichloroethene + toluene, and + p-xylene. For trichloroethene + tetrachloromethane V^E is positive at low mole fractions of C₂HCl₃ and negative at high mole fractions.     

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.     

Positronium as a probe of structure and stability of solid phases in binary n-alkane mixtures

Annihilation of triplet ortho-positronium (o-Ps) in binary mixture of odd numbered n-alkanes was investigated. Sensitivity of o-Ps lifetime to the size of free volumes in the sample structure allows to distinguish not only the phases of solid but also some details of their structure. It was found that in the rigid phase o-Ps locates in the interlamellar gap. In mixed systems the o-Ps lifetime in that phase is longer than in neat compounds due to the change of molecular arrangements around the gap. In the case of n-tricosane + n-nonadecane mixture a transient structure appears when the n-tricosane content is between 3% and 10%. Directly after the increase of temperature to the range of 285–292 K the sample transforms to the rotator phase, but returns (at least partially) to the previous rigid structure with recovery time constant of many hours. Above 292 K the structure is stable.     

Excess molar volumes of binary mixtures (an ionic liquid + water): A review

This review covers recent developments in the area of excess molar volumes for mixtures of {ILs (1) + H₂O (2)} where ILs refers to ionic liquids involving cations: imidazolium, pyridinium, pyrrolidinium, piperidinium, morpholinium and ammonium groups; and anions: tetraborate, triflate, hydrogensulphate, methylsulphate, ethylsulphate, thiocyanate, dicyanamide, octanate, acetate, nitrate, chloride, bromide, and iodine. The excess molar volumes of aqueous ILs were found to cover a wide range of values for the different ILs (ranging from −1.7 cm³ · mol⁻¹ to 1.2 cm³ · mol⁻¹). The excess molar volumes increased with increasing temperature for all systems studied in this review. The magnitude and in some cases the sign of the excess molar volumes for all the aqueous ILs mixtures, apart from the ammonium ILs, were very dependent on temperature. This was particularly important in the dilute IL concentration region. It was found that the sign and magnitude of the excess molar volumes of aqueous ILs (for ILs with hydrophobic cations), was more dependent on the nature of the anion than on the cation.     

Excess enthalpies and excess volumes of binary mixtures containing tetrahydrofuran

Heat of mixing data at 318.15 K are reported for the binary systems made up of tetrahydrofuran (THF) with pyridine and with thiazole.The volumes of mixing at 298.15 K and atmospheric pressure have also been measured for the following binary mixtures: THF+pyridine, THF+thiazole THF + benzene, THF + cyclohexane, THF + hexafluorobenzene.     

Excess volumes of binary mixtures of vinyl acetate and aromatic hydrocarbons

Excess molar volumes of (vinyl acetate  +  toluene, or ethylbenzene, orp -xylene, or isopropylbenzene, or butylbenzene, or isobutylbenzene, or mesitylene, or t -butylbenzene), were determined from density measurements at T =  298.15 K using a vibrating-tube densimeter. The excess molar volumes are positive over the whole composition range, and increase with the size of the hydrocarbon. Steric hindrance in these mixtures was investigated in terms of the partial excess molar volumes behaviour. The experimental data were used to determine the binary interaction parameters of the Soave–Redlich–Kwong (SRK) equation of state for use in multicomponent excess functions calculations.     

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.     

Thermodynamic properties of binary mixtures containing alkanenitriles. II. Excess volumes of alkanenitriles + 1-chloroalkanes

Excess molar volumes of twelve binary alkanenitrile + 1-chloroalkane mixtures (ethanenitrile, propanenitrile or butanenitrile + 1-chlorobutane, + 1-chloropentane, + 1-chlorohexane or + 1-chlorooctane) have been measured using a vibrating-tube densimeter. Excess volumes for these mixtures are positive except for butanenitrile + 1-chlorobutane.     

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 molar enthalpies of binary mixtures for (tributyl phosphate+methanol/ethanol) at 298.15 K

Excess molar enthalpies of binary mixtures for tributyl phosphate (TBP)+methanol/ethanol were measured with a TAM air Isothermal calorimeter at 298.15 K and ambient. The results for xTBP+(1–x)CH₃OH are negative in the whole range of composition, while the values for xTBP+(1–x)C₂H₅OH change from positive values at low x to small negative values at high x. The experimental results have been correlated with the Redlich–Kister polynomial. IR spectra of the mixtures were measured to investigate the effect of hydrogen bonding in the mixture.     

Excess volumes and excess viscosities of binary mixtures of cyclic ethers with bromobenzene

From density and viscosity measurements at 25 and 40°C, excess volumes and excess viscosities of the binary mixtures of a cyclic ether with bromobenzene were determined. The results are correlated by means of a Redlich-Kister type equation and interpreted in terms of molecular interactions.     

Excess molar volumes of binary mixtures of 4-methyl-2-pentanone and some hydrocarbons

Summary Excess molar volumes (V ^E) for binary mixtures of 4-methyl-2-pentanone and some hydrocarbons (cyclohexane, benzene, toluene, andp-xylene) over the whole mole fraction range are determined by density measurement at 293.15 K. The variation of theV ^E values with the composition for all binary systems is symmetrical except for benezene where the dependence is sigmoid. TheV ^E values are positive for the binary mixture of the ketone with cyclohexane. For the other hydrocarbons, theV ^E values are progressively negative over the entire mole fraction range except the system containing benzene, where a few values at higher mole fractions of benzene are positive. The results are discussed in terms of molecular interactions steric effects.

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Molare Zusatzvolumina von binären Mischungen von 4-Methyl-2-pentanon und einigen Kohlenwasserstoffen

Zusammenfassung Molare Zusatzvolumina (V ^E) von binären Mischungen von 4-Methyl-2-pentanon und einigen Kohlenwasserstoffen (Cyclohexan, Benzol, Toluol undp-Xylol) wurden bei 293.15 K durch Dichtemessungen über den gesamten Molenbruchbereich bestimmt. Mit Ausnahme der binären Mischung mit Benzol (sigmoide Kurvenform) ist die Änderung vonV ^E in Abhängigkeit von der Zusammensetzung der Mischungen symmetrisch. Für das System Keton/Cyclohexan sind dieV ^E-Werte stark positiv, während sie für die anderen Gemische negativ sind. Eine Ausnahme bildet wieder das System mit Benzol als Kohlenwasserstoff, wo einige Werte bei höheren Molenbrüchen von Benzol positiv sind. Die Ergebnisse werden im Zusammenhang mit intermolekularen Wechselwirkungen und dem Einfluß sterischer Faktoren diskutiert.

     

Excess molar volumes of (a cycloalkane + a methylcycloalkane)

Using a vibrating-tube densimeter, excess molar volumes V^E have been obtained at 293.15 and 313.15 K for methylcyclopentane +, methylcyclohexane + cycloheptane, and + cyclooctane.     

Excess molar volumes and viscosities of binary mixtures of cyclohexane and n-alkane at 298.15 K

Awwad, A.M. and Salman, M.A., 1986. Excess molar volumes and viscosities of binary mixtures of cyclohexane and n-alkane at 298.15 K. Fluid Phase Equilibria, 25: 195-208.Excess molar volumes, viscosities, excess molar viscosities, and excess molar activation energies of viscous flow were determined for binary mixtures of cyclohexane + n-pentane, + n-hexane, + n-heptane, + n-octane, + n-nonane, + n-decane, + n-dodecane, + n-tetradecane and + n-hexadecane at 298.15 K. The effect of orientational order of n-alkane on solution molar volumes and viscosities is investigated as well as the adequacy of the Flory theory and free volume theories used to predict solution molar volumes and viscosities. For longer n-alkanes V^E, η^E and ΔG*^E are positive and associated with the orientational order.