Molar Isobaric Expansion Research Articles

Volumetric and viscometric properties of amino acids in aqueous maltitol solutions at T = (293.15–323.15) K

The densities and viscosities of the ternary mixtures of glycine, l-alanine, l-valine, l-threonine and l-arginine in aqueous maltitol solutions were measured at T=(293.15–323.15)K under the atmospheric pressure. The apparent molar volume (Vφ), the limiting partial molar volume (Vφ0) and the limiting partial molar volume of transfer (ΔtrVφ0) were obtained in terms of the measured density, then the viscosity B-coefficient was further calculated by the least-square method. Meanwhile, the partial molar isobaric expansion (E20), the isobaric thermal expansion coefficient (α2), the solvation number (nS), the free energies of activation per mole of solvent (Δμ10≠) and per mole of solute (Δμ20≠) were also calculated. The volumetric and viscometric properties were analyzed and discussed according to the interactions between amino acids and maltitol molecules based on the co-sphere overlap model and the transition state theory.

Densities and Molar Isobaric Thermal Expansions of the Water + Formamide Mixture over the Temperature Range from 274.15 to 333.15 K at Atmospheric Pressure

The density of the {water (1) + formamide (2)} mixture has been measured over the whole composition range at temperatures from 274.15 to 333.15 K at atmospheric pressure using the vibration densimeter. The volumetric parameters of the mixture, such as the excess molar volume, molar isobaric thermal expansions, and apparent and partial molar volumes of water and formamide, as well as their limiting values, have been calculated. It was shown that the mixture formation resulted in the volume decrease at all temperatures, and the largest absolute value of the excess molar volume corresponded to the mixture composition of 2H2O-FA. The limiting partial molar volumes of water and formamide increased with the temperature rise. At a temperature of about 323 K the limiting partial molar volume of water became larger than its own molar volume.

Liquid density, viscosity and spectroscopic studies of binary mixture of tetraethylene glycol + 1,2-ethanediamine for CO2 capture

ABSTRACTThermophysical properties for binary mixture of tetraethylene glycol (T4EG) (1) + 1,2-ethanediamine (EDA) (2), a potential scrubbing solution for the absorption of CO2, are very important as well as lacking in the literatures. This work reports densities and viscosities over the entire concentration range for the binary mixture at T = (293.15-318.15) K under atmospheric pressure. According to the experimental density and viscosity values, the mixtures’ excess molar volume (VmE), absolute viscosity deviation (∆η), excess free energies of activation (∆G*E), apparent molar volumes, partial molar volumes and isobaric thermal expansion coefficient were calculated, respectively. Meanwhile, the VmE, ∆η and ∆G*E values were fitted by a Redlich–Kister equation to obtain coefficients. To further study, the Fourier transform infrared, UV-Vis and fluorescence spectra of T4EG + EDA mixtures with various concentrations were measured, and the intermolecular interaction of T4EG with EDA was also discussed as the formation of –OCH2CH2O–H···N(H2)CH2CH2(H2)N···.

Temperature and concentration dependence of volumetric properties of (tetrahydrofuran + methyl acrylate, or + ethyl acrylate, or + n-butyl acrylate, or + tert-butyl acrylate) binary mixtures

The densities, ρ of binary mixtures of tetrahydrofuran (THF) with methyl acrylate (MA), ethyl acrylate (EA), n-butyl acrylate (n-BA) and tert-butyl acrylate (t-BA) over the entire composition range including those of pure liquids, were measured at temperatures (293.15, 298.15, 303.15, 308.15, 313.15, 318.15)K and atmospheric pressure. From the experimental results, the excess molar volume, VmE, excess molar isobaric expansion, Ep,mE, partial molar volumes, V‾m,1 and V‾m,2, excess partial molar volume, V‾m,1E and V‾m,2E, excess partial molar isobaric expansions, E‾p,m,1E and E‾p,m,2E over the whole composition range; partial molar volumes, V‾m,1° and V‾m,2°, and excess partial molar volumes, V‾m,1°E and V‾m,2°E of the components at infinite dilution have been calculated. The variations of these volumetric properties with composition and temperature are discussed in terms of the molecular interactions prevailing in these mixtures. It is observed that the THF-acrylate interactions in these mixtures follow the order: MA>EA>n-BA>t-BA. The values of VmE were also calculated theoretically by using Prigogine-Flory-Patterson (PFP) theory and the results were found in good agreement with the experimental findings.

Standard volumetric characteristics of N-dimethyl-substituted bicyclic bisureas (glycolurils) in water at T = (278.15 to 318.15) K and p ~ 0.1 MPa

Densities of aqueous solutions of achiral cis-dimethylglycoluril (2,8-DMGU) and chiral (in the racemic form) trans-dimethylglycoluril (2,6-DMGU) were measured using a hermetically sealed vibrating-tube densimeter, with an uncertainty of ~1×10−5g∙cm−3, at T=(278.15, 288.15, 298.15, 308.15, and 318.15) K and p=(99.6±0.4) kPa. The solution molality was ranged from (0.037 to 0.396) mol·kg−1 for aqueous 2,6-DMGU and from (0.046 to 0.202) mol·kg−1 for aqueous 2,8-DEGU. The standard (at infinite dilution) molar volumes and isobaric molar expansibilities for the specified N-dimethyl-substituted heterocyclic compounds in water were computed and discussed in comparison with previously derived results for the equimolecular 2,4-dimethylglycoluril (2,4-DMGU) whose isomeric molecules contain simultaneously both the unsubstituted and fully methylated five-membered rings. It was established that the compared glycoluril-derivatives are the prevailingly structure-breaking solutes in water despite of presence of two methyl groups in each of heterocyclic molecules. In other words, the hydrophobic hydration effect is being less pronounced than the hydrophilic hydration or H-bonding effect (via amide and carbonyl groups). The temperature-dependent behavior of packing-related hydration effects was described taking into account the structural (stereochemical) features of a solute molecule.

Temperature and composition dependences of volumetric properties of (water + 1,2-propanediol) binary system

The experimental data on the density of aqueous solutions of 1,2-propanediol over the whole concentration range are performed at different temperatures (278.15, 288.15, 298.15, 308.15, 323.15 and 333.15) K and atmospheric pressure. The density was measured also for the diluted solutions at temperatures from 274.15 to 283.15K with 1K step for examination of 1,2-propanediol influence on the temperature of maximal density (TMD) of water. The apparent molar volume of the mixture components, Vφ,i, the partial molar volumes, Vi, and the partial molar isobaric expansions, Ep,i, were calculated depending on concentration and temperature. The following volumetric parameters were determined for infinite diluted solutions: the partial molar volumes of the mixture components, Vi∞, and the partial molar isobaric expansions, EP,i∞. The results obtained were discussed in terms of solute-solvent and solute-solute interactions. The literature data on the above volume properties of (water+1,2-propanediol) mixture were reviewed. The character of disturbing influence of 1,2-propanediol on the structure of water was established using different approaches to analysis of the volumetric properties. It was shown that the criteria of hydrophobicity examined resulted in contradictory conclusions. Therefore those criteria are to be considered simultaneously for drawing reasonable conclusions.

Some thermophysical properties of methanol and aqueous methanol mixtures at sub- and supercritical conditions

Expressions for the composition dependence of the critical constants of mixtures or water and methanol are presented as are expressions of the vapor pressure, the molar enthalpy of vaporization, and the molar volume of methanol along its saturation curve. The internal pressure of saturated methanol is compared with it cohesive energy density, reflecting the diminishing strength of its intermolecular hydrogen bonding as the temperature is increased. Thermophysical properties (molar volumes, isobaric expansibilities, isothermal compressibilities, and internal pressures) of mixtures of methanol and water at subcritical temperatures at saturation and at the fixed pressures of 7 and 20MPa have been calculated and are presented in a table. The self- and mutual association of water and methanol in their mixtures at sub-critical temperatures is examined.

Volume properties of liquid mixture of {water (1) + ethylenediamine (2)} over the temperature range from 274.15 to 333.15 K at atmospheric pressure

The density of {water (1)+ethylenediamine (2)} binary mixture was measured over the whole concentration range at temperatures from 274.15 to 333.15K and at atmospheric pressure. The experimental values were used to calculate a whole number of the mixture parameters such as the excess molar volumes, molar isobaric expansions, apparent and partial molar volumes, partial molar isobaric expansions, limiting partial molar volumes and limiting partial molar isobaric expansions both of water and ethylenediamine. The extremal dependence of the partial molar volumes of the mixture components was observed; the mixture excess molar volumes were negative at all temperatures and depended weakly on temperature. The concentration dependences of the partial molar volumes of the mixture components were very similar to the dependences for aqueous mixtures of the nonelectrolytes with hydrophobic properties. The mixture molar isobaric expansion increased with ethylenediamine concentration over the whole concentration range. The concentration dependences of partial molar isobaric expansions of both water and ethylenediamine were rather complex and correlated with the mixture melting diagram.

Densities and derived thermodynamic properties for the (n-heptane + n-octane), (n-heptane + ethanol) and (n-octane + ethanol) systems at high pressures

This work reports densities for the pure n-heptane, n-octane and ethanol at temperatures from (288.15 to 413.15)K and at pressures up to 60MPa. The same properties were determined for the binary mixtures n-heptane + n-octane, n-heptane + ethanol and n-octane + ethanol over the temperature range (293.15–373.15)K and at pressures ranging from (0.1 to 40)MPa. Highly precise densimeter DMA HP was used for density measurements. Experimental values of densities were fitted by the modified Tammann–Tait equation. Additionally, derived volumetric properties, e.g. excess molar volumes, isothermal compressibilities and isobaric thermal expansion coefficients were calculated. The effect of pressure and temperature on the measured and derived properties was discussed.

Solution Behavior of p-Coumaric, Caffeic and Ferulic Acids in Methanol as Determined from Volumetric Properties: Attempts to Explore a Correlation with Antioxidant Activities

Apparent molar volumes (Vϕ) and isentropic compressions (KS,ϕ) of three antioxidant compounds, p-coumaric, caffeic and ferulic acids, were determined from accurately measured densities and speeds of sound in methanol at (283.15, 288.15, 293.15, 298.15, 303.15 and 308.15) K. Infinite dilution values of Vϕ and KS,ϕ were obtained, as \( V_{\phi }^{\circ } \) and \( K_{S,\phi }^{\circ } \), by an extrapolation procedure. Apparent molar isobaric expansions at infinite dilution (Eϕo) were also evaluated for the same systems. The variation of \( V_{\phi }^{\circ } \) with temperature is discussed in terms of strength of interactions between the antioxidant compounds and methanol. \( V_{\phi }^{\circ } \) values for the three antioxidant compounds in water at 298.15 K were estimated from group contributions assuming the validity of an additivity rule and are compared with experimentally obtained values in methanol at 298.15 K. Possible correlations between the antioxidant activity of p-coumaric, caffeic and ferulic acids and their volumetric properties, \( V_{\phi }^{\circ } \) and \( K_{S,\phi }^{\circ } \), are discussed.

Thermodynamic study of N-acetyl glycine in aqueous tetraethylammonium iodide solutions in the temperature interval (288.15 to 308.15) K: Volumetric and acoustic study

Knowledge of thermodynamic properties of substituted amino acids in aqueous medium can provide valuable information regarding the stabilisation mechanism of proteins. In this study, we report the density and ultrasonic speeds of N-acetyl glycine in (0.03, 0.05, 0.1, 0.15 and 0.2)mol⋅kg−1 aqueous solutions of tetraethylammonium iodide (TEAI) at temperatures (288.15, 293.15, 298.15, 303.15 and 308.15)K and at pressures 101kPa. From these results, the apparent molar volume and acoustical parameters, coefficient of isentropic compression, molal hydration number and apparent molar isentropic compression have been evaluated. The partial molar volume, partial molar isentropic compression, and their corresponding transfer functions were calculated. These results were used to interpret the type of interactions occurring in the ternary mixtures using the co-sphere overlap model. The pair and triplet interaction coefficients have been calculated from both the properties. The concentration and temperature dependence of (solute+solute) and (solute+solvent) interactions in the present study was also discussed. The partial molar volumes were used to obtain the partial molar isobaric expansibilities for N-acetyl glycine to examine the temperature dependence of such interactions. The structure-making/breaking ability of N-acetyl glycine has also been discussed in terms of the sign of ∂CP,∅0∂PT.

Volumetric behavior of the ternary system (methyl tert-butyl ether + methylbenzene + butan-1-ol) and its binary sub-system (methyl tert-butyl ether + butan-1-ol) within the temperature range (298.15 to 328.15) K

Values of the density and speed of sound were measured for the ternary system (methyl tert-butyl ether+methylbenzene+butan-1-ol) within the temperature range (298.15 to 328.15)K at atmospheric pressure by a vibrating-tube densimeter DSA 5000. Two binary sub-systems were studied and published previously while the binary sub-system (methyl tert-butyl ether+butan-1-ol) is a new study in this work. Excess molar volume, adiabatic compressibility, and isobaric thermal expansivity were calculated from the experimental values of density and speed of sound. The excess quantities were correlated using the Redlich–Kister equation. The experimental excess molar volumes were analyzed by means of both the Extended Real Associated Solution (ERAS) model and the Peng–Robinson equation of state. The novelty of this work is the qualitative prediction of ternary excess molar volumes for the system containing auto-associative compound and two compounds that can hetero-associate. The combination of the ERAS model and Peng–Robinson equation of state could help to qualitatively estimate the real behavior of the studied systems because the experimental results lie between these two predictions.

Standard molar volumes and expansibilities of 1,3-alkyl-N-substituted achiral glycolurils in water at T = (278.15 to 318.15) K and p = 0.1 MPa: A comparative analysis

Densities of aqueous solutions of achiral 1,3-dimethylglycoluril (1,3-DMGU) and 1,3-diethylglycoluril (1,3-DEGU) were measured using a hermetically sealed vibrating-tube densimeter, with an uncertainty of 1·10−5g·cm−3, at T=(278.15, 288.15, 298.15, 308.15, and 318.15)K and p=(99.6±0.8)kPa. The solute molality was ranged from (0.06 to 0.39) and from (0.01 to 0.07)mol·kg−1 for the aqueous 1,3-DMGU and 1,3-DEGU, respectively. The standard (at infinite dilution) molar volumes and isobaric expansibilities for the 1,3-dialkyl-N-substituted glycolurils compared in water were calculated and discussed in comparison with the previously derived molar enthalpies and heat capacities of their dissolution (hydration). The temperature-dependent behavior of packing-related hydration effects was described taking into account the structural features of a solute molecule.

Density and Volumetric Properties of Aqueous Solutions of Trimethylamine N-Oxide in the Temperature Range from (278.15 to 323.15) K and at Pressures up to 100 MPa

Densities of aqueous solutions of trimethylamine N-oxide (TMAO) were measured over the concentration range (0.0875 to 4.3251) mol·kg–1 at temperatures (278.15, 288.15, 298.15, 308.15, and 323.15) K and pressures (0.101, 10, 25, 50, 75, and 100) MPa. Volumetric properties such as apparent molar volume of TMAO, Vϕ,2, molar isothermal compression, KT,m, molar isobaric expansion, EP,m, and internal pressure, Pint, of its aqueous solutions were calculated depending on concentration, temperature, and pressure. The volumetric partial properties of TMAO at infinite dilution in water (V2∞, KT,2∞, and EP,2∞) were also determined. The results were discussed from the standpoint of solute–solute and solute–solvent interactions.

Physico-Chemical Studies of Glycine, L-Alanine, L-Phenylalanine and Glycylglycine in Aqueous Triton X-100 at Different Temperatures

Abstract The densities, ρ and viscosities, η of glycine (Gly), L-alanine (Ala), L-phenylalanine (Phe) and glycylglycine (Gly-Gly) in aqueous Triton X-100 (TX-100) solutions have been measured as a function of amino acid/peptide concentration at 298.15, 303.15, 308.15 and 313.15 K. The experimental data have been utilized to evaluate various thermodynamic parameters, viz., apparent molar volumes, V 2, partial molar volumes at infinite dilution, V 0 2, partial molar isobaric expansibilities, ϕ 0 2, partial molar volumes of transfer, Δ tr V 0 2 and A and B-coefficients of viscosity, respectively. The hydration numbers have also been calculated. The results have been discussed in terms of interactions taking place in the present systems. The structure-making/-breaking ability of the solute (amino acid/peptide) in the presence of surfactant, Triton X-100 has also been considered.

Volumetric properties of binary liquid-phase mixture of (water + glycerol) at temperatures of (278.15 to 323.15) K and pressures of (0.1 to 100) MPa

The coefficients of compressibility, k=ΔV/Vo, of liquid binary mixture of {water (1)+glycerol (2)} were measured over the whole composition range at pressures from (0.1 to 100)MPa and temperatures from (278.15 to 323.15)K. Excess molar volumes of the mixture, VmE, partial molar volumes of the mixture components, V¯i, as well as their limiting values, molar isothermal compression KT,m, molar isobaric expansion EP,m, molar isochoric elasticity (isochoric coefficient of thermal pressure) βm were calculated. It was revealed that with glycerol molar fraction increasing the coefficients of compressibility, k, decreased to x2≈0.3÷0.4 (where x2 was glycerol molar fraction), and further changed insignificantly. It was shown that all isobars of excess molar volumes were negative and their absolute values, VmE, decreased on temperature and pressure rising. No extremes were observed on concentration dependences of partial molar volumes of glycerol in the mixture at its low concentrations. Under the state parameters studied limiting partial volumes of water and glycerol decrease with pressure rising but increase with temperature growth. Dependences of molar isothermal compression and molar isochoric elasticity on glycerol molar fraction passed extremes, and similar dependences of molar isobaric expansion had the temperature inversion regions.

Densities, Excess Molar Volumes, and Thermal Expansion Coefficients of Aqueous Aminoethylethanolamine Solutions at Temperatures from 283.15 to 343.15K.

The densities of aqueous mixtures of aminoethylethanolamine (CAS #000111-41-1) were measured over the entire compositional range at temperatures of 283.15–343.15 K. The results of these measurements were used to calculate excess molar volumes and isobaric thermal expansion coefficients, and partial molar and apparent molar volumes and excess isobaric thermal expansion coefficients were subsequently derived. The excess molar volumes were correlated as a function of the mole fraction using the Redlich–Kister equation. Temperature dependences of the Redlich–Kister coefficients are also presented. The partial molar volumes at infinite dilution of AEEA in water were determined using two different methods. In addition, the solution density was correlated using a Joubian–Acree model. Aqueous solutions of AEEA exhibit similar properties to the aqueous solutions of other alkanolamines (like monoethanolamine) used in acid gas sweetening.

The Effect of Pressure and Temperature on the Second-Order Derivatives of the Free Energy Functions for Lower Alkanediols

The second-order derivatives of the free energy functions, i.e., isochoric molar heat capacities, isentropic and isothermal molar compressibility, and isobaric and isentropic molar thermal expansion, were calculated in the temperature range from (293.15 to 318.15) K and at pressures up to 100 MPa for 1,2- and 1,3-propanediol; 1,2-, 1,3, and 1,4-butanediol; and 2-methyl-2,4-pentanediol. The data for calculations were obtained by means of the acoustic method. The pressure and temperature dependencies for the above mentioned properties are analyzed and discussed together with the literature data on isobaric molar heat capacities. The observed marked difference between isobaric and isentropic thermal expansion is analyzed as well. The differences in behavior of linear 1,2-diols and $$\upalpha ,\upomega $$ -diols as well as a diol with a branched carbon chain are emphasized. The isentropic and isothermal molar compressibilities are used to evaluate the dimensionality and relative rigidity of H-associates.

Characterization of the volumetric properties of betaine in aqueous solutions: Compositional, pressure, and temperature dependence

Densities, ρ, at atmospheric pressure and coefficients of compressibility, k, at p = (10, 25, 50, 75, 100) MPa were measured for aqueous solutions of N,N,N-trimethylglycine (betaine) at T = (278.15, 288.15, 298.15, 308.15 323.15) K. The experimental data have been used to calculate the following volumetric parameters: the apparent molar volume of betaine, Vϕ,2, the molar isothermal compression, KT,m, and the molar isobaric expansion, EP,m, of solutions at all pressures and temperatures studied. Some parameters for infinite dilute solution of betaine in water were also obtained such as limiting partial molar volumes, V2∞, limiting partial molar isothermal compressions, KT,2∞, and limiting partial molar isobaric expansions, EP,2∞. The variation of all these parameters with composition, temperature, and pressure were discussed from the viewpoint of intermolecular interactions in the system.

Bulk properties of a liquid phase mixture {ethylene glycol+tert-butanol} in the temperature range 278.15–348.15 K and pressures of 0.1–100 MPa. II. Molar isothermal compressibility, molar isobaric expansibility, thermal pressure coefficient, and internal pressure

Based on the experimental data, the molar isothermal compressibilities, molar isobaric expansibilities, thermal pressure coefficients, internal pressures of a liquid phase mixture {ethylene glycol (1) + tert-butanol (2)} are calculated for a wide spectrum of compositions in the range of pressures of 0.1–100 MPa and temperatures of 278.15–323.15 K. Shown that the dependences of molar isothermal compressibilities KT, m, molar isobaric expansibilities EP, m, and isochoric thermal pressure coefficients β on the mole fraction of tert-butanol in the mixture are characterized by the absence of extrema typical of aqueous systems. The manifestation of negative partial expansibility and negative partial expansibility of ethylene glycol in the mixture is found. The thermal pressure coefficients decrease with an increase in the mole fraction of tert-butanol at all pressures and temperatures. A rise in the pressure increases the thermal pressure coefficient, while a rise in the temperature decreases its value due to a decrease of free space in the mixture. An increase in the concentration of tert-butanol leads to an increase in the negative temperature coefficient of internal pressure ΔPint/ΔT, which indicates a weakening of intermolecular interaction at these compositions.