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1.
Coexistence curves of ( T, n), ( T, ϕ), and ( T, Ψ), where n, ϕ, and Ψ are the refractive index, volume fraction and effective volume fraction ψ = ϕ / {ϕ +  [(1   ϕ )ϕc / (1   ϕc )]}, respectively, for ternary microemulsion systems of {water  + n -nonane  +  sodium di(2-ethyl-1-hexyl)sulphosuccinate} have been determined at temperatures within 8.7 K above the critical temperature by measurements of refractive index at constant pressure and a constant molar ratio of water to sodium di(2-ethyl-1-hexyl)sulphosuccinate. The critical exponent β deduced from ( T,n ), ( T, ϕ), and ( T, Ψ) coexistence curves was found consistent with nonmonotonic crossover observed in all aqueous ionic solutions. The values of β deduced from the experimental data in the range of 1 K above Tcwere consistent with the universality class of three-dimensional Ising-like systems. The coexistence curves have been interpreted by a combination of the Wegner expansion and the rectilinear diameter. The present results indicate that the molar mass dependence of critical amplitudes, we proposed recently, is valid for microemulsion systems.  相似文献   

2.
(Vapour + liquid) equilibrium data (water activity, vapour pressure, osmotic coefficient, and activity coefficient) of binary aqueous solutions of 1-hexyl-3-methylimidazolium chloride ([C6mim][Cl]), methyl potassium malonate, and ethyl potassium malonate and ternary {[C6mim][Cl] + methyl potassium malonate} and {[C6mim][Cl] + ethyl potassium malonate} aqueous solutions were obtained through the isopiestic method at T = 298.15 K. These results reveal that the ionic liquid behaves as surfactant-like and aggregates in aqueous solutions at molality about 0.4 mol · kg−1. The constant water activity lines of all the ternary systems investigated show small negative deviations from the linear isopiestic relation (Zdanovskii–Stokes–Robinson rule) derived using the semi-ideal hydration model. The density and speed of sound measurements were carried out on solutions of methyl potassium malonate and ethyl potassium malonate in water and of [C6mim][Cl] in aqueous solutions of 0.25 mol · kg−1 methyl potassium malonate and ethyl potassium malonate at T = (288.15 to 308.15) K at atmospheric pressure. From the experimental density and speed of sound data, the values of the apparent molar volume, apparent molar isentropic compressibility and excess molar volume were evaluated and from which the infinite dilution apparent molar volume and infinite dilution apparent molar isentropic compressibility were calculated at each temperature. Although, there are no clear differences between the values of the apparent molar volume of [C6mim][Cl] in pure water and in methyl potassium malonate or ethyl potassium malonate aqueous solutions, however, the results show a positive transfer isentropic compressibility of [C6mim][Cl] from pure water to the methyl potassium malonate or ethyl potassium malonate aqueous solutions. The results have been interpreted in terms of the solute–water and solute–solute interactions.  相似文献   

3.
Densities of aqueous solutions with molalities up to 6 mol · kg−1 were determined at 5 K temperature intervals, from T = 288.15 K to T = 333.15 K. Densities served to evaluate the apparent molar volumes, V2,ϕ(m, T), the cubic expansion coefficients, α(m, T), and the changes of isobaric heat capacities with respect to pressure, (∂CP/∂P)T,m. They were qualitatively correlated with the changes in the structure of water when glutaric acid is dissolved in it.  相似文献   

4.
The apparent molar volume and apparent molar isentropic compressibility of solutions of sodium di-hydrogen phosphate (NaH2PO4) in (1-propanol + water) mixed-solvent media with alcohol mass fractions of 0.00, 0.05, 0.10, and 0.15 are reported over the range of temperature (283.15 to 303.15) K at 5 K intervals. The results were fitted to a Redlich–Mayer type equation from which the apparent molar volume and apparent molar isentropic compressibility of the solutions at the infinite dilution were also calculated at the working temperature. The results show a positive transfer volume of NaH2PO4 from an aqueous solution to an aqueous 1-propanol solution. The apparent molar isentropic compressibility of NaH2PO4 in aqueous 1-propanol solutions is negative and it increases with increasing the concentration of NaH2PO4, 1-propanol, and temperature. Electrical conductivity and refractive index of the solutions are also studied at T = 298.15 K. The effects of the electrolyte concentration and relative permittivity of the medium on the molar conductivity were also investigated.  相似文献   

5.
The apparent molar volumes and isentropic compressibility of glycine, l-alanine and l-serine in water and in aqueous solutions of (0.500 and 1.00) mol · kg?1 di-ammonium hydrogen citrate {(NH4)2HCit} and those of (NH4)2HCit in water have been obtained over the (288.15 to 313.15) K temperature range at 5 K intervals at atmospheric pressure from measurements of density and ultrasonic velocity. The apparent molar volume and isentropic compressibility values at infinite dilution of the investigated amino acids have been obtained and their variations with temperature and their transfer properties from water to aqueous solutions of (NH4)2HCit have also been obtained. The results have been interpreted in terms of the hydration of the amino acids. In the second part of this work, water activity measurements by the isopiestic method have been carried out on the aqueous solutions of {glycine + (NH4)2HCit}, {alanine + (NH4)2HCit}, and {serine + (NH4)2HCit} at T = 298.15 K at atmospheric pressure. From these measurements, values of vapour pressure, osmotic coefficient, activity coefficient and Gibbs free energy were obtained. The effect of the type of amino acids on the (vapour + liquid) equilibrium of the systems investigated has been studied. The experimental water activities have been correlated successfully with the segment-based local composition Wilson model. Furthermore, the thermodynamic behaviour of the ternary solutions investigated has been studied by using the semi-ideal hydration model and the linear concentration relations have been tested by comparing with the isopiestic measurements for the studied systems at T = 298.15 K.  相似文献   

6.
Experimental results of density (ρ), speed of sound (u), and refractive index (nD) have been obtained for aqueous solutions of ethylene glycol monomethyl ether (EGMME), ethylene glycol monoethyl ether (EGMEE), diethylene glycol monomethyl ether (DEGMME), and diethylene glycol monoethyl ether (DEGMEE) over the entire concentration range at T = 298.15 K. From these measurements, the derived parameters, apparent molar volume of solute (?V), excess molar volume (VE), isentropic compressibility of solution (βS), apparent molar isentropic compressibility of solute (?KS), deviation in isentropic compressibility (ΔβS), molar refraction [R]1,2 and deviation in refractive index of solution (ΔnD) have been calculated. The Redlich–Kister equation has been fitted to the calculated values of VE, ΔβS and ΔnD for the solution. The results obtained are interpreted in terms of hydrogen bonding and various interactions among solute and solvent molecules.  相似文献   

7.
The densities of tetra-n-butylammonium bromide in 1-propanol, 1-butanol, acetone at (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 323.15) K and sound velocities at 298.15 K have been measured. From these data apparent molar volumes VΦ at (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 323.15) K and the apparent molar isenotropic compressibility KS,Φ, at T = 298.15 K of tetrabutylammonium bromide in nonaqueous solvents have been determined. The apparent molar volumes and the apparent molar isenotropic compressibilities were fitted to the Redlich, Rosenfeld, and Mayer equation as well as to the Pitzer equation yielding infinite dilution data, which were compared to the similar quantities for tetrabutylphosphonium bromide. Moreover, the acoustical parameters such as intermolecular free length (Lf), relative association (RA), Rao’s molar sound function (Rm), and salvation number (Sn) were calculated using the experimental data of density and sound velocity at T = 298.15 K for ammonium and phosphonium bromides. The obtained data suggest the penetration of the acetone molecule within the intraionic free space of the tetrabutyl-ammonium and phosphonium cations.  相似文献   

8.
The (p, ρ, T) properties and apparent molar volumes Vϕ of CaCl2 in methanol at T = (298.15 to 398.15) K, at pressures up to 40 MPa are reported, and apparent molar volumes have been evaluated. The experimental (p, ρ, T) values were described by an equation of state. The experiments were carried out at m = (0.10819, 0.28529, 0.65879 and 2.39344) mol · kg−1 of calcium chloride.  相似文献   

9.
The densities at T = (293.15, 298.15, 303.15, 308.15, 310.15, and 313.15) K and sound velocities at T = (298.15 and 310.15) K have been measured for pentaerythritol in pure water and in (1, 5, and 10) wt% aqueous solutions of sodium and magnesium chloride. From these data apparent molar volumes, VΦ, and the apparent molar isenotropic compressibilities, KS,Φ, of the polyol have been determined. The limiting apparent molar quantities and corresponding transfer parameters were also obtained and discussed in terms of various solute–solvent and solute–cosolute interactions.  相似文献   

10.
In the present communication, we report the fundamental thermodynamic properties like volumetric and compressibility of very important bioactive compounds, viz. quinine hydrochloride, guanidine hydrochloride and quinic acid (0.01 to 0.1) mol · kg−1 in water at temperatures T = (278.15, 288.15 and 298.15) K. The experimental values of density (ρ) of aqueous solutions and speed of sound (u) in aqueous solutions of the above compounds within the concentration range (0.01 to 0.1) mol · kg−1 have been obtained. The apparent molar volumes (Vϕ), and apparent molar isentropic compressibilities (κϕ) of quinine hydrochloride, guanidine hydrochloride and quinic acid in water have been computed at three different temperatures. Speed of sound values have also been used to calculate the hydration number (nH) of the solute. The temperature dependence of the apparent molar volume has been used to calculate the thermal expansion coefficient (α1), apparent molar expansivity (Eϕ0) and Hepler’s constant 2Vϕ0/T2. The derived parameters have been used to interpret the results in terms of (solute + solute)/(ion + ion), (solute + solvent) interactions, structure making and structure breaking tendencies of solutes in water.  相似文献   

11.
The (p, ρ, T) properties and apparent molar volumes Vϕ of LiNO3 in methanol at T = (298.15 to 398.15) K and pressures up to p = 40 MPa are reported. An empirical correlation for the apparent molar volumes of lithium nitrate in methanol with pressure, temperature and molality has been derived. For the solutions the experiments were carried out at molalities m = (0.15512, 0.29425, 0.53931, 0.89045, 1.80347, and 3.61398) mol · kg−1 of lithium nitrate.  相似文献   

12.
Apparent molar volumes Vϕ and apparent molar heat capacities Cp,ϕ were determined at the pressure 0.35 MPa for aqueous solutions of magnesium nitrate Mg(NO3)2 at molalities m = (0.02 to 1.0) mol · kg−1, strontium nitrate Sr(NO3)2 at m = (0.05 to 3.0) mol · kg−1, and manganese nitrate Mn(NO3)2 at m = (0.01 to 0.5) mol · kg−1. Our Vϕ values were calculated from solution densities obtained at T = (278.15 to 368.15) K using a vibrating-tube densimeter, and our Cp,ϕ values were calculated from solution heat capacities obtained at T = (278.15 to 393.15) K using a twin fixed-cell, differential, temperature-scanning calorimeter. Empirical functions of m and T were fitted to our results, and standard state partial molar volumes and heat capacities were obtained over the ranges of T investigated.  相似文献   

13.
We have measured the densities of aqueous solutions of l-methionine, l-methionine plus equimolal HCl, and l-methionine plus equimolal NaOH at temperatures 278.15  T/K  368.15, at molalities 0.0125  m/mol · kg−1  1.0 as solubilities allowed, and at p = 0.35 MPa using a vibrating tube densimeter. We have also measured the heat capacities of these solutions at 278.15  T/K  393.15 and at the same m and p using a twin fixed-cell differential temperature-scanning calorimeter. We used the densities to calculate apparent molar volumes Vϕ and the heat capacities to calculate apparent molar heat capacities Cp,ϕ for these solutions. We used our results and values from the literature for Vϕ(T, m) and Cp,ϕ(T, m) for HCl(aq), NaOH(aq), and NaCl(aq) and the molar heat capacity change ΔrCp,m(T, m) for ionization of water to calculate parameters for ΔrCp,m(T, m) for the two proton dissociations from protonated aqueous cationic l-methionine. We integrated these results in an iterative algorithm using Young’s Rule to account for the effects of speciation and chemical relaxation on Vϕ(T, m) and Cp,ϕ(T, m). This procedure yielded parameters for Vϕ(T, m) and Cp,ϕ(T, m) for methioninium chloride {H2Met+Cl(aq)} and for sodium methioninate {Na+Met(aq)} which successfully modeled our observed results. Values are given for ΔrCp,m, ΔrHm, pQa, ΔrSm, and ΔrVm for the first and second proton dissociations from protonated aqueous l-methionine as functions of T and m.  相似文献   

14.
The speed of sound and density measurements in water, methanol, and benzene solutions for the solutes PEG-400, PEG-1000, and PEG-4000 at T = 298.15 K (0.05 to 0.5 mol · kg−1) are reported. The data obtained are used to calculate thermodynamic parameters such as adiabatic (isentropic) compressibility of solutions (βad), apparent molar volume (ϕV) and apparent molar compressibility (ϕK) for solute molecules in all the solvent media. The limiting partial molar volume (ϕV) and limiting partial molar compressibility (ϕK) of solute molecules are used to estimate volume of transfer and compressibility of transfer for PEG molecules from methanol to aqueous and benzene to aqueous media. The high observed negative (ϕK) values in methanol are interpreted in terms of breakdown of one-dimensional H-bonded structure of methanolic molecules. The (ϕK) values observed in water although negative but of small magnitude as compared to salts in water. Attempt is made to estimate hydration number for these molecules in aqueous solutions by applying Shiio’s method and it is observed that PEG-4000 is hydrated most. These results are discussed in terms of solute–solvent and hydrophobic interactions and effects due to conformational characteristic of high molecular weight glycol molecules.  相似文献   

15.
We have measured the densities of aqueous solutions of alanine, alanine plus equimolal HCl, and alanine plus equimolal NaOH at temperatures 278.15  T/K  368.15, at molalities 0.0075  m/mol · kg−1  1.0, and at the pressure p = 0.35 MPa using a vibrating tube densimeter. We have also measured the heat capacities of these solutions at 278.15  T/K  393.15 and at the same m and p using a twin fixed-cell differential temperature-scanning calorimeter. We used the densities to calculate apparent molar volumes Vϕ and the heat capacities to calculate apparent molar heat capacities Cp,ϕ for these solutions. We used our results and values from the literature for Vϕ(T, m) and Cp,ϕ(T, m) for HCl(aq), NaOH(aq), and NaCl(aq) and the molar heat capacity change ΔrCp,m(T, m) for ionization of water to calculate parameters for ΔrCp,m(T, m) for the two proton dissociations from protonated aqueous cationic alanine. We integrated these results in an iterative algorithm using Young’s Rule to account for the effects of speciation and chemical relaxation on Vϕ(T, m) and Cp,ϕ(T, m). This procedure yielded parameters for Vϕ(T, m) and Cp,ϕ(T, m) for alaninium chloride {H2Ala+Cl(aq)} and for sodium alaninate {Na+Ala(aq)} which successfully modeled our observed results. Values are given for ΔrCp,m, ΔrHm, pQa, ΔrSm, and ΔrVm for the first and second proton dissociations from protonated aqueous alanine as functions of T and m.  相似文献   

16.
We have measured the densities of aqueous solutions of serine, serine plus equimolal HCl, and serine plus equimolal NaOH at temperatures 278.15  T/K  368.15, molalities 0.01  m/mol · kg−1  1.0, and at the pressure p = 0.35 MPa, using a vibrating tube densimeter. We have also measured the heat capacities of these solutions at 278.15  T/K  393.15 and at the same m and p using a fixed-cell differential temperature-scanning calorimeter. We used the densities to calculate apparent molar volumes Vϕ and the heat capacities to calculate apparent molar heat capacities Cp,ϕ for these solutions. We used our results and values from the literature for Vϕ(T,m) and Cp,ϕ(T,m) for HCl(aq), NaOH(aq), and NaCl(aq) and the molar heat capacity change ΔrCp,m(T,m) for ionization of water to calculate ΔrCp,m(T,m) for proton dissociations from protonated aqueous cationic serine and from the zwitterionic form. We integrated these results in an iterative algorithm using Young’s rule to account for the effects of speciation and chemical relaxation on the observed Vϕ(T,m) and Cp,ϕ(T,m) of the solutions. This procedure yielded parameters for Vϕ(T,m) and Cp,ϕ(T,m) for serinium chloride {H2Ser+Cl(aq)} and for sodium serinate {Na+Gly(aq)} which successfully modeled our observed results. We have then calculated ΔrCp,m, ΔrHm, ΔrVm and pQa for the first and second proton dissociations from protonated aqueous serine as functions of T and m.  相似文献   

17.
The densities of tetraphenylphosphonium bromide, sodium tetraphenylborate, lithium perchlorate, sodium perchlorate and lithium bromide in γ-butyrolactone at (288.15, 293.15, 298.15, 303.15, 308.15 and 313.15) K and speed of sound at 298.15 K have been measured. From these data apparent molar volumes VΦ at (288.15, 293.15, 298.15, 303.15, 308.15 and 313.15) K and the apparent molar isentropic compressibility KS,Φ, at T = 298.15 K of the salts have been determined. The apparent molar volumes and the apparent molar isentropic compressibilities were fitted to the Redlich, Rosenfeld and Mayer equation as well as to the Pitzer and Masson equations yielding infinite dilution data. The obtained limiting values have been used to estimate the ionic data of the standard partial molar volume and the standard partial isentropic compressibility in γ-butyrolactone solutions.  相似文献   

18.
Density and ultrasound speed were measured accurately for diglycine + water, triglycine + water, diglycine + water-polyethylene glycol 400 (PEG400) and triglycine + water-PEG400 solutions at T = (293.15, 298.15, 303.15 and 308.15) K. The results were used in evaluating thermodynamic properties as apparent molar volumes (VØ) and apparent molar isentropic compressions (K) of diglycine and triglycine in water and in PEG400 solutions. Infinite dilution values of these parameters, VoØ, and Ko, were obtained from their plots as a function of molality by extrapolation and have been utilized in obtaining transfer volumes and transfer compressions at infinite dilution. All transfer volumes and transfer compressions were found to increase with increasing molality of PEG400. Apparent molar isobaric expansions were derived from the temperature dependence of VØ values at infinite dilution and at finite concentrations. All the results were interpreted in terms of solute (diglycine or triglycine) and co-solute (PEG400) and solvent (H2O) interactions.  相似文献   

19.
Density, sound velocity, and viscosity of 1-ethyl-3-methylimidazolium bromide, [Emim][Br], in aqueous solutions of tri-potassium phosphate with salt weight fractions (ws = 0.00, 0.10, 0.15, and 0.20) have been measured as a function of concentration of [Emim][Br] at atmospheric pressure and T = (298.15, 303.15, 308.15, 313.15, and 318.15) K. The apparent molar volume, isentropic compressibility, apparent isentropic compressibility, and relative viscosity values have been evaluated from the experimental data. The partial molar volume and isentropic compressibility at infinite dilution, and viscosity B-coefficient obtained from these data have been used to calculate the corresponding transfer parameters for the studied IL from water to the aqueous tri-potassium phosphate solutions. Also, an empirical equation was satisfactorily used to correlate the experimental viscosity data.  相似文献   

20.
We have measured the densities of aqueous solutions of glycine, glycine plus equimolal HCl, and glycine plus equimolal NaOH at temperatures 278.15  T/K  368.15, molalities 0.01  m/mol · kg−1  1.0, and at p = 0.35 MPa, using a vibrating tube densimeter. We have also measured the heat capacities of these solutions at 278.15  T/K  393.15 and at the same m and p using a fixed-cell differential scanning calorimeter. We used the densities to calculate apparent molar volumes Vϕ and the heat capacities to calculate apparent molar heat capacities Cp,ϕ for these solutions. We used our results and values of Vϕ(T, m) and Cp,ϕ(T, m) for HCl(aq), NaOH(aq), NaCl(aq) from the literature to calculate parameters for ΔrCp,m(T, m) for the first and second proton dissociations from protonated aqueous cationic glycine. We then integrated this value of ΔrCp,m(T, m) in an iterative algorithm, using Young’s Rule to account for the effects of speciation and chemical relaxation on the observed Vϕ and Cp,ϕ of the solutions. This procedure yielded parameters for Vϕ(T, m) and Cp,ϕ(T, m) for glycinium chloride {H2Gly+Cl(aq)} and sodium glycinate {Na+Gly(aq)} which successfully modeled our observed results. We have then calculated values of ΔrCp,m, ΔrHm, ΔrVm, and pQa for the first and second proton dissociations from protonated aqueous glycine as functions of T and m.  相似文献   

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