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.     

Enthalphy of mixing of bromobenzene with n-alkanes,with cyclohexane,and with benzene

A dynamic flow microcalorimeter of the Picker design was used to measure enthalpies of mixing at 298.15 K and atmospheric pressure of the six binary systems bromobenzene + n-hexane, + n-heptane, + n-nonane, + n-tetradecane, + cyclohexane, and + benzene. Within the homologous series of n-alkane systems, the interaction parameter, h₁₂, calculated from rigid-lattice group contribution theory, decreases weakly with increasing chain length of the alkane. This behavior is quite analogous to that observed with chloro-derivatives of benzene + n-alkane.     

Excess volumes for n-alkanols + n-alkanes I. Binary mixtures of methanol,ethanol, n-propanol,and n-butanol + n-heptane

Excess volumes V^E measured at 298.15 K in a successive-dilution dilatometer are reported for binary mixtures of the n-alkanols C₁ to C₄ + n-heptane. For ethanol +, and n-butanol + n-heptane, the measurements were extended to high dilutions of alkanol. V^E is positive for all of the mixtures but decreases rapidly in magnitude for increasing chain length of the n-alkanol. The results were used to estimate the excess partial molar volumes of the components.     

Excess heat capacities and excess volumes of binary liquid mixtures of 1,1,1,-trichloroethane with cyclic ethers at 298.15 K

Measurements of volumetric heat capacities at constant pressure, C_p/V (V being the molar volume), at 298.15 K, of the binary liquid mixtures 1,1,1-trichloroethane + oxolane, +1,3-dioxolane, +oxane, +1,3-dioxane, and +1,4-dioxane were carried out in a Picker-type flow microcalorimeter. Molar heat capacities at constant pressure. C_p, and molar excess heat capacities, C^E_p, were calculated from these results as a function of the mole fraction. C^E_p values for these systems are positive and the magnitude depends on the size of the cycle and on the relative position of the oxygen atoms in the cyclic diethers. The precision and accuracy for C^E_p are estimated as better than 2%. Molar excess volumes, V^E, for the same systems, at 298.15 K, have been determined from density measurements with a high-precision digital flow densimeter. The experimental results of V^E and C^E_p, are interpreted in terms of molecular interactions.     

Thermodynamic properties of binary mixtures containing n-alkylamines: I. Isothermal vapour–liquid equilibrium and excess molar enthalpy of n-alkylamine+toluene mixtures. Measurement and analysis in terms of group contributions

Molar excess enthalpies, H^E, at 303.15 K and atmospheric pressure, of n-propyl-, n-butyl-, n-pentyl-, n-octyl- or n-decylamine+toluene, as well as the isothermal vapour–liquid equilibria, VLE, of n-butylamine+toluene and of n-butylamine+benzene at 298.15 K have been determined. These experimental results, along with the data available in the literature on molar excess Gibbs energies, G^E, activity coefficients at infinite dilution, γ_i^∞, and molar excess enthalpies, H^E, for n-alkylamine+toluene mixtures are examined on the basis of the DISQUAC group contribution model. The modified UNIFAC is also used to describe the mixtures.     

Thermodynamic properties of (a pentyl ester + an-alkane). XIV. The HmEand VmEfor (an ester + an-alkane)

This paper presents experimental data for the excess molar enthalpies H_m^Eand excess molar volumes V_m^Eat T =  298.15 K and atmospheric pressure for 21 binary mixtures consisting of one of three pentyl esters (ethanoate, propanoate, and pentanoate) and one of seven odd n -alkanes (from pentane to heptadecane). The results have shown the mixing of these mixtures to be endothermic, with H_m^Evarying uniformly with the n -alkane chain length. The variation of V_m^Ewas also found to be uniform, with contraction effects observed for the mixtures that contained low molecular-weight hydrocarbons, and increasing with the pentyl ester chain length. Different group-contribution theories were used to calculate the excess properties for (an ester  +  an n -alkane). Comparison of the calculated and experimental results revealed that, in most cases, the differences increased with the molecular weight of the components. However, the differences for the calculated values of the excess volumes using the model of Nitta et al. decreased with n -alkane chain length but increased with ester chain length, the mean differences for the excess volumes being larger than 20 per cent.     

Excess enthalpies of some aromatic aldehydes in n-hexane, n-heptane and benzene

Calorimetric measurements of molar excess enthalpies, H^E, at 298.15 K, of mixtures containing aromatic aldehydes of general formula C₆H₅(CH₂)_mCHO (with m = 0, 1 and 2) + n-hexane, n-heptane or benzene are reported, together with the values of H^E at equimolar composition compared with the corresponding values of H^E for the aromatic ketones in the same solvents. The experimental results clearly indicate that the intermolecular interactions between the carbonyl groups (CHO) are influenced by the intramolecular interactions between the carbonyl and phenyl groups, particularly for the mixtures containing benzaldehyde.     

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.     

Excess heat capacities and excess volumes of binary liquid mixtures of chloroform with cyclic ethers at 298.15 K

Molar excess heat capacities at constant pressure, C^E_p, of binary liquid mixtures chloroform + oxolane, chloroform + 1,3-dioxolane, chloroform + oxane, and chloroform + 1,4-dioxane have been determined at 298.15 K from measurements of volumetric heat capacities in a Picker flow microcalorimeter. A precision of ±0.04 J K^?1 mole^? was achieved by using the stepwise procedure. Experimental molar excess heat capacities are compared with values derived from H^E results at different temperatures. Excess molar volumes, V^E, for the same systems at 298.15 K have been determined by measuring the density of the pure liquids and solutions with a high-precision digital flow densimeter.     

Excess volumes and isobaric heat capacities of diisopropyl ether with several alkanols at 298.15 K: Application of the symmetrical extended real associated solution model

Excess molar volumes v^E and isobaric heat capacities C_p^E at 298.15 K were measured for 11 mixtures of diisopropyl ether (DIPE)+alcohol (from methanol to 1-undecanol), DIPE with n-heptane and 2,4-dimethylpentane with 1-octanol. Moreover the excess molar enthalpy h^E of DIPE with n-heptane at the same temperature was also measured in order to obtain the self-association parameters of the symmetrical extended real associated solution (SERAS) model for DIPE. Parameters of the SERAS model corresponding to the interaction of DIPE with each alcohol were obtained by fitting v^E data reported here and h^E data taken from a previous work. The results obtained are compared with those from the literature obtained by using the ERAS model in the traditional way for several of the studied mixtures. C_p^E curves are qualitatively explained in terms of the SERAS model.     

Analysis of Excess Molar Volumes of the Ternary Systems Containing a Propyl Alkanoate and Two Alkanes with Some Predictive Methods

Abstract

Excess molar volumes at 298.15 K of the ternary mixtures (propyl ethanoate + n-heptane + n-decane), (propyl propanoate + n-heptane + n-decane) and (propyl butanoate + n-heptane + n-decane) were determined using a DMA 60/602 Anton Paar densimeter. All the experimental values were compared with the results obtained with empirical expressions for estimating ternary properties from binary data and with the Nitta-Chao group-contribution model. For these ternary mixtures the same behaviour that had been observed in ester + n-alkane binary systems was found: excess volumes decrease when the ester length increases.     

Thermodynamics of liquid mixtures containing a very strongly polar compound: Part 6. DISQUAC characterization of N,N-dialkylamides

Systems of N,N di(n-alkylamides) (hereafter, N,N-dialkylamides) with alkane, benzene, toluene, 1-alkanol or 1-alkyne have been investigated in the framework of the DISQUAC model. The corresponding interaction parameters are reported. They change regularly with the molecular structure of the mixture components. This variation is similar to those encountered when treating other systems in terms of DISQUAC. The model describes consistently a whole set of thermodynamic properties: liquid–liquid equilibria (LLE), vapor–liquid equilibria (VLE), solid–liquid equilibria (SLE), molar excess Gibbs energies (G^E), molar excess enthalpies (H^E), molar excess heat capacities at constant pressure (C_P^E), partial molar excess properties at infinite dilution, enthalpies and heat capacities. The model also provides good results for the Kirkwood–Buff integrals and for the linear coefficients of preferential solvation. For ternary systems, DISQUAC predictions on VLE and H^E, obtained using binary parameters only, are in good agreement with the experimental data. A short comparison between DISQUAC and Dortmund UNIFAC results is shown. DISQUAC improves UNIFAC results on H^E and C_P^E, magnitudes which strongly depend on the molecular structure. The investigated mixtures behave similarly to those characterized by thermodynamic properties which arise from dipolar interactions. Association/solvation effects do not play, as a whole, an important role in the studied systems. This may explain that the ERAS model fails when representing the thermodynamic properties of dimethylformamide + 1-alkanol mixtures.     

Excess enthalpies for n-alkane/ -carotene+n-alkane/AOT/water systems

The experimental data of excess enthalpies for β-carotene/n-alkane+n-alkane/AOT/water systems at 298.15 K are reported. The H_E dependence on AOT (sodium bis(2-ethylhexyl) sulfosuccinate) concentration and hydrocarbon chain length was investigated. The excess enthalpy was measured using the flow microcalorimeter UNIPAN type 600.     

Volumetric Properties of Ternary-Pseudobinary Mixtures Containing Benzene and Cyclohexane

Densities have been measured as a function of composition for ternary-pseudobinary mixtures of [(benzene + toluene or methylcyclohexane) + (cyclohexane + toluene or methylcyclohexane)] by means of a vibrating-tube densimeter at atmospheric pressure and the temperature 298.15 K. The excess molar volumes, V_m^E, were calculated from the densities and correlated using the Redlich–Kister equation to estimate the coefficients and standard errors. The experimental and calculated quantities are used to discuss the mixing behavior of the components. The results show the third component, toluene and methylcyclohexane, influences the interaction between benzene and cyclohexane.     

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.     

Thermodynamics of molecular interactions in binary mixtures of non-electrolytes. Molar excess volumes

Molar excess volumes, V^E, for pyridine (A) + α-picoline (B), + β-picoline (B) and + γ-picoline (B) and benzene (A) + toluene (B), + o-xylene (B) and + p-xylene (B) and carbon tetrachloride (A) + n-heptane (B) have been measured dilatometrically as a function of temperature and composition and have been utilized to study B—B and B—B—B interactions in the presence of A via the Mayer—McMillan approach. A model has also been presented to account for these B—B and B—B—B interactions. The V^E data at 308.15 K have also been analysed in terms of the “graph theoretical” approach which describes the V^E data well for all these mixtures at 308.15 K. The “graph theoretical” approach has further been extended to successfully evaluate V^E data for a mixture at any temperature, T₂, when the V^E data at T₁ are known.     

Excess molar volumes at 298.15 K of binary liquid organic mixtures containing n-alkanones and linear ethers: Application of Flory’s theory

Excess molar volumes, V_m^E, at 298.15 K and atmospheric pressure over the entire composition range for binary mixtures of 2-butanone with di-n-butyl ether and 2-pentanone and 3-pentanone with di-n-butyl ether and 2,5-dioxahexane, 2-heptanone and 4-heptanone with di-n-butyl ether, 2,5-dioxahexane and 3,6,9-trioxaundecane are reported from densities measured with a vibrating-tube densimeter. All the excess volumes present strong contractions when compared to those of n-alkanone+n-alkane systems.Molar excess enthalpies H_m^E and V_m^E of the considered mixtures vary similarly. This may be attributed to interactional effects which prevail over structural effects.Flory’s theory has been applied to the systems under study. As expected, results for H_m^E are better when the difference in polarity of the components of the mixture decreases. V_m^E is often poorly represented.     

Excess Molar Volumes of Binary Mixtures of Propyl Ethanoate with some n-Alkanes at 298.15 K and 308.15 K

Abstract

Excess molar volumes v^E have been measured for the binary liquid mixtures of propyl ethanoate with five n-alkanes (n-hexane, n-heptane, n-octane, n-nonane and n-decane) at 298.15 and 308.15 K, using an Anton Paar densimeter. All the mixtures studied present positive v^E values that increase with the length of the chain of the alkane and with the temperature. The experimental results are compared with the predictions of the Nitta—Chao model.     

Excess enthalpies and excess volumes of 1-nitropropane +, and 2-nitro-propane +, each of several non-polar liquids

Excess molar enthalpies H_m^E and excess molar volumes V_m^E have been measured for xC₃H₇NO₂ + (1 ? x)c-C₆H₁₂ at 298.15 and 318.15 K; +(1 ? x)CCl₄ at 298.15 and 318.15 K; +(1 ? x)C₆H₆ at 298.15 and 318.15 K; +(1 ? x)C₆H₁₄ (V_m^E only) at 298.15 K; +(1 ? x)p-C₆H₄(CH₃)₂ at 298.15 K; and for xCH₃CH(NO₂)CH₃ + (1 ? x)c-C₆H₁₂ at 298.15 and 318.15 K; +(1 ? x)CCl₄ at 298.15 and 318.15 K; +(1 ? x)C₆H₆ at 298.15 K; +(1 ? x)C₆H₁₄ at 298.15 K; +(1 ? x)(CH₃)₂CHCH(CH₃)₂ for H_m^E at 318.15 K and for V_m^E at 298.15 K; and +(1 ? x)C₁₆H₃₄ at 298.15 K. The H_m^E′s were determined with an isothermal dilution calorimeter and the V_m^E′s with a continuous-dilution dilatometer. Particular attention was paid to the region dilute in nitroalkane. In general H_m^E is large and positive for (a nitropropane + an alkane), less positive for (a nitropropane + tetrachloromethane), and small for (a nitropropane + benzene) and for (a nitropropane + 1,4-dimethylbenzene). The mixture with hexadecane shows phase separation. V_m^E is large and positive for (1-nitropropane + cyclohexane), less positive for (1-nitropropane + hexane), and S-shaped for (1-nitropropane + tetrachloromethane) with negative values in the 1-nitropropane-rich region. For (1-nitropropane + benzene) and for (1-nitropropane + 1,4-dimethylbenzene) V_m^E is negative. For mixtures with 2-nitropropane the results are similar except that for benzene V_m^E is S-shaped with positive values in the 2-nitropropane-rich region.