Excess Molar Isobaric Heat Capacities Research Articles

Thermophysical and Acoustical Properties of the Binary Mixtures 1,2-Dibromoethane + Heptane within the Temperature Range from 293.15 K to 313.15 K

Densities for binary mixtures 1,2-dibromoethane + heptane have been measured within the temperature range from 293 K to 313 K using a vibrating-tube densimeter. The phase speeds of ultrasound have been measured with a pulse−echo−overlap apparatus. The heat capacities at constant pressure have been measured with a differential scanning calorimeter DSC III (Setaram). From those experimental data, the excess molar volumes, excess isobaric molar heat capacities, excess isochoric molar heat capacities, excess molar isobaric expansions, excess molar isentropic compressions, excess molar isothermal compressions, excess ultrasonic speeds, and excess internal pressures have been calculated.

Heat Capacity, Speed of Ultrasound, and Density for 1,5-Dibromopentane + Heptane within the Temperature Range from 293.15 K to 313.15 K

Densities for binary mixture 1,5-dibromopentane + heptane have been measured within the temperature range from 293 K to 313 K using a vibrating tube densimeter. The phase speeds of ultrasound have been measured with a pulse−echo−overlap apparatus. The heat capacities at constant pressure have been measured with a differential scanning calorimeter DSC III (Setaram). From those experimental data, the excess molar volumes, VE, excess isobaric molar heat capacities, , excess isentropic compressibilities, , excess isothermal compressibilities, , and excess ultrasonic speeds, uE, were calculated.

Isobaric molar heat capacities of the ternary system dimethyl carbonate + p-xylene + n-decane

Isobaric molar heat capacities at atmospheric pressure were determined for the ternary system dimethyl carbonate + p-xylene + n-decane and the corresponding binary mixtures dimethyl carbonate + p-xylene, dimethyl carbonate + n-decane and p-xylene + n-decane over the whole composition range at 288.15, 298.15 and 308.15 K. From these data, excess isobaric molar heat capacities were calculated using the Benson and Kiyohara's criterion. The obtained values for the binary systems were correlated using a Redlich–Kister polynomial, whereas the ternary contribution was fitted by means of the Nagata equation. The data present a gradual crossover from a W-shaped composition dependence, typical in alkyl carbonate + alkane systems, to negative parabolic curves, often found for alkyl carbonate + aromatic hydrocarbon and for aromatic + linear hydrocarbon systems. The results are discussed in terms of the degree of randomness of the mixtures.

Thermodynamic behaviour of the binary systems dimethyl carbonate + n-octane or n-nonane

Isobaric molar heat capacities, densities and speeds of sound were determined for the dimethyl carbonate + n-octane and n-nonane systems at atmospheric pressure covering the whole composition interval and in the temperature range (288.15–308.15 K). From these data, derived properties and excess magnitudes were obtained. A strongly temperature-dependent W-shaped curves against composition were observed for excess isobaric molar heat capacities in both system, showing the other excess magnitudes regular tendencies. From these results, a comparative analysis of the existing differences between the thermodynamic behaviour of the two systems was carried out.

Excess isobaric molar heat capacities and excess molar volumes for ethanol + n-decane and n-undecane systems

Densities between (278.15 and 308.15) K and isobaric heat capacities per unit volume from (280.15 to 308.15) K for ethanol + n-decane and n-undecane systems were determined at atmospheric pressure over the whole composition range. From these data, excess molar volumes and excess isobaric molar heat capacities were calculated by means of the Benson and Kiyohara’s criterion. Results were analyzed in terms of the well-known microscopic effects that take place in alkanol + n-alkane systems. Their dependence with the size of the linear alkane was studied with the help of literature data of short alkyl chain 1-alkanol + long alkyl chain alkane systems.

Excess molar heat capacities for (1-butanol + 1,3-butanediol) at temperatures from (285 to 353) K

The molar isobaric heat capacities for the binary mixtures (1-butanol + 1,3-butanediol) were determined in the temperature range from (285 to 353) K from measurements of isobaric specific heat capacity in a differential scanning calorimeter. The composition dependencies of the excess molar isobaric heat capacities obtained from the experimental results were fitted by the Redlich–Kister polynomials. Below the temperature 318.15 K, the excesses are positive and between the temperatures (323.15 and 348.15) K the excess curves are s-shaped. At the temperature 353.15 K, the excess is negative. In addition, the molar isochoric heat capacities at the temperature 298.15 K were estimated.

Thermodynamic Properties of Dodecane + 1-Butanol and + 2-Butanol Systems

Densities and speeds of sound in the temperature interval (278.15 to 318.15) K and heat capacities per unit volume from (283.15 to 318.15) K were determined for the dodecane + 1-butanol and + 2-butanol systems. Measurements were made over the whole composition range and at atmospheric pressure. From these data, excess molar volumes, excess isentropic compressibilities, and excess isobaric molar heat capacities were calculated. Results were critically compared with literature data of systems containing these butanol isomers. Differences between both systems were ascribed to the different association ability of the two alcohols.

Thermodynamics of Mixtures Involving Some Linear or Cyclic Ketones and Cyclic Ethers. 4. Systems Containing 1,3-Dioxolane

Densities, ρ, refractive indices, n, and volumetric heat capacities, Cp/V, have been measured at 298.15 K over the whole concentration range for the binary mixtures {1,3-dioxolane + 2-pentanone, + 2-heptanone, or + cyclopentanone}. From the experimental data, excess molar volumes, VE, excess molar refractions, RE, and excess molar isobaric heat capacities, , were calculated. Deviations of refractive index from ideality were determined by using a deviation function defined on a volume fraction basis, Δnφ. Excess molar enthalpies HE have been measured at the same temperature for the systems {1,3-dioxolane + 2-pentanone, + 2-heptanone, + cyclopentanone, or + cyclohexanone}. The results are discussed in terms of destruction of quadrupolar and dipolar order, setting up of unlike-pair interactions, degrees of free volume, and influence of the size and shape of the ketone. Moreover, data obtained in this work and earlier parts of the series are comprehensively examined.

Thermodynamics of Mixtures Involving Some Linear or Cyclic Ketones and Cyclic Ethers. 3. Systems Containing 1,4-Dioxane

Densities ρ, refractive indices n, and volumetric heat capacities Cp/V have been measured at 298.15 K over the whole concentration range for the binary mixtures {1,4-dioxane + 2-pentanone, + 2-heptanone, or + cyclopentanone}. From the experimental data, excess molar volumes VE, excess molar refractions RE, and excess molar isobaric heat capacities were calculated. Deviations of the refractive index from ideality were determined by using a deviation function defined on a volume fraction basis, Δnφ. Excess molar enthalpies HE have been measured at the same temperature for the systems {1,4-dioxane + 2-pentanone, + 2-heptanone, + cyclopentanone, or + cyclohexanone}. The discussion of these quantities is made in terms of destruction of quadrupolar order in 1,4-dioxane, setting-up of unlike-pair interactions, degrees of free volume, and influence of the size and shape of the ketone. Moreover, the results are compared with those obtained in part 2 of this series for a homologous set of systems containing tetrahydropyran.

Thermodynamic Excess Properties of the 1-Alkylamine + Alkane and di-n-Alkylamine + Alkane Systems in Terms of an Associated Mixture Model with Equation of State Contribution

AbstractThe model proposed by Treszczanowicz and Benson (1985) is applied for the description and interpretation of excess enthalpyHE, excess volumeVEand excess molar isobaric heat capacityCEpof the binary systems formed by 1-alkylamines and dialkyl-amines withn-alkanes. In the model, the self-association contribution is described by an athermal associated mixture model with the continuous mode of association of the Mecke–Kempter type and the equation of state contribution described by the Flory theory. The three self-association parameters: enthalpy, entropy and volume are valid over the whole homologous series of 1-alkylamines and dialkylamines. The equation of state interaction parameters are correlated for both series of mixtures with the structure of the component molecules by using the Kehiaian–Guggenheim group contribution method. The model predicts reasonably wellHEas well asVEfor both these classes of mixtures.

Thermodynamics of Mixtures Involving Some Linear or Cyclic Ketones and Cyclic Ethers. 2. Systems Containing Tetrahydropyran

Densities ρ, refractive indices n, and volumetric heat capacities Cp/V have been measured at 298.15 K over the whole concentration range for the binary mixtures {tetrahydropyran + 2-pentanone, + 2-heptanone, or + cyclopentanone}. From the experimental data, excess molar volumes VE, excess molar refractions RE, and excess molar isobaric heat capacities were calculated. Deviations of refractive index from ideality were determined by using a deviation function defined on a volume fraction basis, Δnφ. Excess molar enthalpies HE have been measured at the same temperature for the systems {tetrahydropyran + 2-pentanone, + 2-heptanone, + cyclopentanone, or + cyclohexanone}. The discussion of these quantities entails a comparison with the results obtained in part 1 of this series for a homologous set of systems containing tetrahydrofuran.

Thermophysical Properties of the Binary Mixtures Diethyl Carbonate + (n-Dodecane or n-Tetradecane) at Several Temperatures

The density and the speed of sound at (288.15, 293.15, 298.15, and 308.15) K and the isobaric molar heat capacity at (288.15, 298.15, and 308.15) K of binary mixtures of diethyl carbonate with n-dodecane or n-tetradecane were measured at atmospheric pressure, over the entire composition range. These results are used to calculate molar volumes, isentropic and isothermal compressibilities, isobaric thermal expansivities, and isobaric and isochoric molar heat capacities as well as the corresponding excess quantities. Positive values and a parabolic composition dependence were found for all excess quantities except for the excess molar heat capacities, which take negative values and are W-shaped. Excess molar volumes increase with both alkyl chain length of the n-alkane and temperature. Excess isobaric molar heat capacities decrease as the size of the n-alkane increases and exhibit different temperature dependences with mole fraction. All other properties, with the exception of the excess isochoric molar heat...

Thermodynamic properties of binary mixtures { x(2-alkoxyethanol)+(1− x) n-octane}: densities at 298.15 and 303.15 K and speeds of sound at 298.15 K

Densities and speeds of sound of the mixtures { x(2-ethoxyethanol), or x(2-propoxyethanol), or x(2-isopropoxyethanol), or x(2-butoxyethanol), or x(2-isobutoxyethanol)+(1− x)( n-octane)} were measured at 298.15 K, densities were also measured at 303.15 K. Excess molar volumes, excess isentropic and isothermal compressibilities, excess isochoric heat capacities and excess isobaric thermal expansivities were calculated therefrom. The excess molar volumes are positive and rather large. The excess isobaric thermal expansivities are positive and large as usual for polar mixtures but the excess isothermal and isentropic compressibilities are small. Derived excess molar isobaric heat capacities are in good agreement with the predicted values obtained with UNIFAC and DISQUAC group contribution models.

Excess molar volumes and excess molar heat capacities of (dimethyl carbonate, or diethyl carbonate +n-heptane) at several temperatures

Excess molar volumes were determined over the whole composition range for (dimethyl carbonate, or diethyl carbonate+n -heptane) at the temperatures (278.15, 288.15, 298.15, and 308.15) K, and at atmospheric pressure with a vibrating-tube densimeter. In addition, a differential scanning calorimeter was used to obtain excess isobaric molar heat capacities for the same mixtures at the temperatures (288.15, 298.15, and 308.15) K, and at atmospheric pressure. The infuence of the upper critical solution temperature on the measured properties is also discussed.

Excess volumes and excess heat capacities of nitromethane+(1-propanol or 2-propanol)

Densities and heat capacities of binary mixtures containing nitromethane+(1-propanol or 2-propanol) were determined at the temperatures (288.15, 293.15, 298.15, and 308.15) K and atmospheric pressure, over the whole composition range. Excess molar volumes and excess molar isobaric heat capacities were calculated from the results thus obtained. The effect of specific interactions on the excess properties, and the dependence on the position of the OH group in the alkanol, are analysed.

Heat Capacities, Excess Enthalpies, and Volumes of Mixtures Containing Cyclic Ethers. 3. Binary Systems {Tetrahydrofuran, Tetrahydropyran, 1,4-Dioxane, or 1,3-Dioxolane + Cyclohexane or Toluene}

Excess molar volumes for {1,4-dioxane or 1,3-dioxolane + cyclohexane} and excess molar enthalpies and isobaric excess molar heat capacities for the binary mixtures {tetrahydrofuran, tetrahydropyran, 1,4-dioxane, or 1,3-dioxolane + cyclohexane or toluene} at the temperature 298.15 K have been determined as a function of mole fraction. The magnitude of these experimental quantities is discussed in terms of the nature and type of intermolecular interactions in binary mixtures. When available, the results have been compared with literature values.

Excess molar volumes and excess molar heat capacities of (2, 5, 8, 11-tetraoxadodecane + C4H8O2ester isomers) at several temperatures

Excess molar volumes of (2, 5, 8, 11-tetraoxadodecane + propyl formate or methyl propanoate) at the temperatures (278.15, 288.15, 298.15, and 308.15) K and atmospheric pressure were obtained from density measurements with a vibrating-tube densimeter. Excess molar isobaric heat capacities of (2, 5, 8, 11-tetraoxadodecane + propyl formate) at the temperatures (288.15, 298.15, and 308.15) K and atmospheric pressure were determined with a differential scanning calorimeter. The results are compared with literature values of binary mixtures containing C4H8O2ester isomers.

Excess Molar Volumes and Excess Molar Heat Capacities of Mixtures Containing (Mono and Poly)ethers + Ethyl Acetate

Excess molar volumes were obtained from density measurements for binary mixtures of ethyl acetate [CH3COOCH2CH3] with glymes [CH3O(CH2CH2O)nCH3, n = 1, 2, 3, and 4] and dibutyl ether [(CH3CH2CH2CH2)2O] at (278.15, 288.15, 298.15, and 308.15) K and atmospheric pressure using a Kyoto Electronics DA-210 vibrating-tube densimeter. In addition, excess molar isobaric heat capacities were determined for ethyl acetate with glymes (n = 2, 4) and dibutyl ether at 298.15 K using a micro DSC II differential scanning calorimeter.

Thermodynamic properties of polyoxyethyleneglycol dimethyl ether+ n-alkane mixtures

Excess molar volumes V m E at 278.15, 288.15, 298.15 and 308.15 K and atmospheric pressure were obtained from density measurements with a vibrating-tube densimeter for the mixtures CH 3O(CH 2CH 2O) m CH 3 ( m=2, diglyme; m=3, triglyme; m=4, tetraglyme)+ n-dodecane. These results allowed us to calculate isobaric thermal expansivities α at 298.15 K. We also report excess molar isobaric heat capacities C p E at atmospheric pressure measured with a micro DSC II differential scanning calorimeter for the systems triglyme+ n-heptane at 288.15, 298.15 and 308.15 K and triglyme+ n-dodecane at 283.15, 288.15, 298.15 and 308.15 K.

Excess thermodynamic properties of mixtures of cyclohexanone and benzene at 298.15 and 308.15 K and the effect of excess expansion factor

Excess molar isobaric heat capacity, density and speed of sound of a cyclohexanone and benzene mixture were measured at 298.15 and 308.15 K. From densities, excess volumes were calculated at two temperatures and the excess expansion factor of the mixture was estimated. The excess expansion factor was negative and large, and affected the estimation of isothermal compressibility and isochoric heat capacity from density, speed of sound, isobaric heat capacity and expansion factor.