Properties Of Liquid Mixtures Research Articles

Studies on the importance of nature of substituent on the thermodynamic and transport properties of liquid mixtures at various temperatures

Values of the density (ρ), speed of sound (u), and viscosity (η) are reported for binary mixtures of 3-chloroaniline with substituted benzene derivatives viz., chlorobenzene, bromobenzene and nitrobenzene over the entire composition range of mole fraction at T=(303.15–318.15)K and at atmospheric pressure 0.1MPa. The excess properties such as excess molar volume, excess isentropic compressibility and deviation in viscosity were calculated from the density, speed of sound and viscosity. Excess properties were correlated by the Redlich–Kister equation. The partial molar volumes, partial molar isentropic compressibility, excess partial molar volume and excess partial molar isentropic compressibility were calculated for all the binary systems throughout the composition range and also at infinite dilution. The VE results were analyzed in the light of the Prigogine–Flory–Patterson theory. Analysis of each of the three contributions viz. interactional, free volume and P∗ to VE show that the interactional contribution is positive for all systems, the free volume effect is negative for all the mixtures and the P∗ contribution is negative for all the mixtures except nitrobenzene which shows a positive internal pressure. The variations of these parameters with composition and temperature are discussed in terms of intermolecular interactions prevailing in these mixtures.

To Polarize or Not to Polarize? Charge-on-Spring versus KBFF Models for Water and Methanol Bulk and Vapor-Liquid Interfacial Mixtures.

Simulations of water and methanol mixtures using polarizable force fields (FFs) for methanol (COS/M and CPC) and water (COS/G2) were performed and compared to experiment and also to a nonpolarizable methanol (KBFF) model with SPC/E water in an effort to quantify the importance of explicit electronic polarization effects in bulk liquid mixtures and vapor-liquid interfaces. The bulk liquid mixture properties studied included the center of mass radial distribution functions, Kirkwood-Buff integrals (KBIs), volumetric properties, isothermal compressibility, enthalpy of mixing, dielectric constant, and diffusion coefficients. The vapor-liquid interface properties investigated included the relative surface probability distributions, surface tension, excess surface adsorption, preferred surface molecule orientations, and the surface dipole. None of the three FFs tested here was clearly superior for all of the properties examined. All the force fields typically reproduced the correct trends with composition for both the bulk and interfacial system properties; the differences between the force fields were primarily quantitative. The overall results suggest that the polarizable FFs are not, at the present stage of development, inherently better able to reproduce the studied bulk and interfacial properties-despite the added degree of explicit transferability that is, by definition, built into the polarizable models. Indeed, the specific parametrization of the FF appears to be just as important as the class of FF.

FT-IR Spectroscopic study of excess thermodynamic properties of liquid mixtures containing N-methylformamide with 2-alkoxyethanols at various temperatures

Densities, speeds of sound and viscosities were measured for the binary mixtures N-methylformamide (NMF) with 2-alkoxyethanols (2-methoxyethanol (ME), 2-ethoxyethanol (EE) and 2-butoxyethanol (BE)) at T=(303.15 to 318.15) K. These experimental data have been used to calculate excess volume (VE), excess isentropic compressibility (κsE), deviation in viscosity (∆η) and excess Gibbs free energy of activation of viscous flow (G⁎E). The excess partial molar volumes, V̅m,1E and V̅m,2E and excess partial molar volumes V̅m,1°E, and V̅m,2°E at infinite dilution have also been calculated. The variations of these properties with composition of binary mixtures suggest loss of dipolar association, difference in size and shape of the component molecules, dipole–dipole interaction and hydrogen bonding between unlike molecules. The excess parameters have been fitted to the Redlich–Kister equation and the results were analyzed in terms of acid–base interactions, hydrogen bond, and dipole–dipole interaction between unlike molecules. Further, the FTIR spectra have been recorded at 298.15K and found to be useful for understanding the presence of hydrogen bonding between oxygen atom of carbonyl group of N-methylformamide and hydrogen atom of the –OH group of 2-alkoxyethanols molecules in the present liquid mixtures. A good agreement is obtained between excess quantities and spectroscopic data.

P024 燃焼生成微粒子を混合した液体の熱物性に関する研究(メカボケーション学生研究発表セッション)

P024 燃焼生成微粒子を混合した液体の熱物性に関する研究(メカボケーション学生研究発表セッション)

Understanding positive and negative deviations in polarity of ionic liquid mixtures by pseudo-solvent approach.

Physico-chemical properties of liquid mixtures in general display large deviations from linear behaviour, arising out of complex specific and non-specific intermolecular interactions. The polarity of liquid mixtures displaying large positive and negative deviations can be minimized and linear mixing can be achieved in liquids using a pseudo-solvent methodology. The work described herein is designed to investigate the influence of different physical parameters on the linear pseudo-solvent composition in ionic liquid mixtures. For this purpose, we have determined the deviations from linearity, ΔE values (defined as given by ) for binary mixtures of a variety of ionic liquids, including two molecular solvents, DMSO and formamide. Firstly, the investigations were carried out in three 1-butyl-3-methylimidazolium cation based aprotic ionic liquids and the roles of anionic structure and hydrogen bond acceptor basicities (β values) of the ionic liquids were determined. The influence of the cationic structure, i.e., the hydrogen bond donor acidity (α values) and non-associative nature of the ionic liquids, was determined using C2-methylated analogs, 1-butyl-2,3-dimethylimidazolium cation based ionic liquids. The role of the protic nature of ionic liquids was studied in two protic ionic liquids, viz., 1-methylimidazolium formate and 1-methylimidazolium acetate. The effects of the temperature, pseudo-solvent structure and solvatochromic probe structure on the ΔE values were also explored.

Phase transition and chemical decomposition of liquid carbon dioxide and nitrogen mixture under extreme conditions**Project supported by the National Natural Science Foundation of China (Grant Nos. 11374217, 11135012, and 11375262) and the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics (Grant No. 11176020).

Thermodynamic and chemical properties of liquid carbon dioxide and nitrogen (CO2–N2) mixture under the conditions of extremely high densities and temperatures are studied by using quantum molecular dynamic (QMD) simulations based on density functional theory including dispersion corrections (DFT-D). We present equilibrium properties of liquid mixture for 112 separate density and temperature points, by selecting densities ranging from ρ = 1.80 g/cm3 to 3.40 g/cm3 and temperatures from T = 500 K to 8000 K. In the range of our study, the liquid CO2–N2 mixture undergoes a continuous transition from molecular to atomic fluid state and liquid polymerization inferred from pair correlation functions (PCFs) and the distribution of various molecular components. The insulator–metal transition is demonstrated by means of the electronic density of states (DOS).

Preferential Solvation in Binary and Ternary Mixtures.

Preferential solvation has become a useful tool to help characterize and understand the properties of liquid mixtures. Here, we provide a new quantitative measure of preferential solvation in binary and ternary mixtures that uses Kirkwood-Buff integrals as input, but differs from traditional measures. The advantages of the new measure are highlighted and compared with established literature approaches. Molecular dynamics simulations are performed to further investigate the nature of binary mixtures, as described by the new and existing measures of preferential solvation. It is shown that the new measure of preferential solvation is rigorous, has a simple physical interpretation, can be easily related to the underlying thermodynamic properties of the mixture, and naturally leads to zero values for ideal mixtures.

Effect of water content on physicochemical properties and electrochemical behavior of ionic liquids containing choline chloride, ethylene glycol and hydrated nickel chloride

We investigated the effect of water addition on some physicochemical properties of liquid mixtures containing choline chloride, ethylene glycol, nickel chloride and extra water in the molar ratio of 1:2:1:x (i.e. ethaline+NiCl2+xH2O) where x was equal to 6, 9, 12 or 18. The influence of water upon density, viscosity, conductivity, and surface tension of ionic liquids is established for temperatures between 25 and 80°C. An increase in the water content leads to decreasing density, viscosity and surface tension and to increasing conductivity. All these results are rationalized in terms of hole theory. The conductivity and viscosity of the liquid mixtures are controlled by the ionic mobility and the availability of voids of suitable dimensions. With increasing water content the average hole sizes increases which makes ionic motion considerably easier. There is a strong linear correlation between activation energies for conductivity and viscosity. Cyclic voltammograms recorded on Ni substrate in ionic liquids under consideration show that the electrochemical process of metal deposition is irreversible. An increase in water content in ethaline+NiCl2+xH2O mixtures leads to the deceleration of Ni electrodeposition reaction.

Ultrasonic and 31P NMR investigations of an acidic nuclear extractant with some monosubstituted benzenes

The ultrasonic velocity, density and viscosity of an acidic nuclear extractant namely di(2-ethylhexyl) phosphoric acid (D2EHPA) and its binary mixtures with three monosubstituted benzenes, viz., nitrobenzene, chlorobenzene and toluene were determined at temperature T=303.15K and at pressure p=0.1MPa. The experimental values were utilised to compute relaxation time, excess molar volume, excess Gibbs energy of activation of viscous flow, deviations in intermolecular free length, acoustic impedance, ultrasonic velocity and viscosity. The excess/deviation functions were fitted to fourth order Redlich–Kister type polynomial equation to estimate binary coefficients and standard errors between experimental and calculated data. The nature of these functions was utilised to speculate the nature of molecular interaction between component molecules of all studied binary mixtures. Furthermore, 31P NMR spectra of pure D2EHPA and its binary mixtures with the monosubstituted benzenes were used to assess molecular interactions between components of liquid mixtures at microscopic level and to corroborate with the results obtained from bulk properties of liquid mixtures.

FT-IR spectroscopic study of excess thermodynamic properties of liquid mixtures containing benzylalcohol with alkoxyalkanols

Densities (ρ) of pure liquids and their mixtures have been measured at T=298.15K to T=318.15K and 0.1MPa pressure over the entire composition range for the binary mixtures of benzylalcohol (BA) with 2-Methoxyethanol (ME), 2-Ethoxyethanol (EE), 2-Butoxyethanol (BE) by using Rudolph Research Analytical digital densitometer (DDH-2911 model). Further, the speed of sound (u) for the above said mixtures was also measured at T=298.15K and T=308.15K. Values of the experimental density were used to calculate the excess volumes (VE), in turn were compared with Redlich–Kister and Hwang equations. Isentropic compressibility (κS) and excess isentropic compressibility (κSE) were evaluated from experimental speed of sound and density data. Moreover, the experimental speed of sound was analysed in terms of theoretical models, namely Schaaff’s collision factor theory (CFT) and Jacobson’s free length theory (FLT). The experimental results are discussed in terms of intermolecular interactions between component molecules of binary mixtures and also FT-IR Spectroscopic studies.

Experimental triplet and quadruplet fluctuation densities and spatial distribution function integrals for pure liquids.

Fluctuation solution theory has provided an alternative view of many liquid mixture properties in terms of particle number fluctuations. The particle number fluctuations can also be related to integrals of the corresponding two body distribution functions between molecular pairs in order to provide a more physical picture of solution behavior and molecule affinities. Here, we extend this type of approach to provide expressions for higher order triplet and quadruplet fluctuations, and thereby integrals over the corresponding distribution functions, all of which can be obtained from available experimental thermodynamic data. The fluctuations and integrals are then determined using the International Association for the Properties of Water and Steam Formulation 1995 (IAPWS-95) equation of state for the liquid phase of pure water. The results indicate small, but significant, deviations from a Gaussian distribution for the molecules in this system. The pressure and temperature dependence of the fluctuations and integrals, as well as the limiting behavior as one approaches both the triple point and the critical point, are also examined.

Deviation of polarity from linearity in liquid mixtures containing an ionic liquid.

The physico-chemical properties of liquid mixtures, in general, exhibit deviations from linear behaviour with respect to their composition, arising out of different types of cross-intermolecular interactions (both specific and non-specific). These specific and non-specific interactions can however be monitored to obtain the linear mixing in liquid mixtures using the pseudo-solvent methodology in such a manner that the interactions causing deviations from linearity are cancelled out and mixtures display linear behaviour.

A review of molecular interactions in organic binary mixtures

The intention of this review article is to review the knowledge about interactions in organic binary liquid mixtures. Molecular interactions in organic binary liquid mixtures are interesting due to their extensive use in many fields of solution chemistry. The thermodynamics of component molecules present in various systems interacting are particularly interesting because they display fantastic results. Studies of different organic liquid mixtures represent the different modes of interactions prevailing in the component molecules. The number of parameters required describing the properties of a given class of mixtures increases sharply with the number of segment types involved. In recent years, the theoretical and experimental investigations of interactions between unlike molecules have been conveniently carried out using excess thermodynamic functions. The properties of liquid mixtures depend on the forces between molecules and on the nature and volume of these molecules, and change with the composition of the mixtures. This change, in turn, is reflected in the thermodynamic properties of the mixtures. The influence of significant contributions of a chemical, physical and geometrical nature that change excess thermodynamic properties is considered and explained in detail.

Thermodynamic Properties of Liquid Mixtures Deduced from Ultrasonic Speed and Viscosity

Excess molar isentropic compressibilities KS, m E and the deviation u of the speeds of sound u from those in the ideal mixtures u, from speeds of sound values are reported. Measurements have been carried out in order to assess the effects of increasing the alkyl chain length of alkane. Further, we have calculated the ideal and excess internal pressures for the binary mixtures 2-butanol + alknae and some other parameters like heat of vaporization, cohesive energy density, solubility parameter, free volume which have been calculated from the internal pressure are also reported. Various physicochemical parameters like intermolecular free length, acoustic impedance, molecular association, relative association, available volume for the pure components as well as for the binary mixtures have also been calculated along with some of their excess counterparts. Results have been discussed in terms of intermolecular interactions.

Volume properties of liquid mixture of water + glycerol over the temperature range from 278.15 to 348.15 K at atmospheric pressure

Densities of {water (1)+glycerol (2)} binary mixture have been measured with vibrational densimeter over the whole concentration range within the temperature interval 278.15–348.15K. Excess molar volumes and molar isobaric expansions of the mixture, apparent and partial molar volumes, as well partial molar isobaric expansions of water and glycerol in the mixture, limiting partial molar volumes and limiting partial molar isobaric expansions of water and glycerol have been calculated. It was shown that the mixture densities increased on the glycerol molar fraction rising at every temperature studied, and at low glycerol concentrations this increase was more pronounced. Magnitudes of excess molar volumes of the mixture were negative at all temperatures. But the deviation from ideality decreased with temperature growth. Molar isobaric expansions of the mixture increased almost linearly when glycerol concentration went up. Concentration dependences of partial molar isobaric expansions of water and glycerol were characterized by extremes occurrence.

Studies of thermodynamic, thermophysical and partial molar properties of liquid mixtures of diethylenetriamine with alcohols at 293.15 to 313.15 K

This paper presents densities, ρ speeds of sound, u and viscosities η of the binary liquid mixtures containing diethylenetriamine with 1-hexanol, 1-octanol and 1-decanol at 293.15, 298.15, 303.15, 308.15 and 313.15K. From density and speed of sound data, excess molar volumes, VmE and deviations in isentropic compressibility, ∆κS and speed of sound, ∆u have been evaluated. Viscosity data were used to compute deviations in viscosity and excess Gibbs energy of activation of viscous flow, ΔG⁎E at 298.15, 303.15 and 308.15K. A Redlich–Kister type equation was applied to fit the excess molar volumes and deviations in isentropic compressibility, speed of sound and viscosity data. The viscosity data have been correlated with the equations of Grunberg–Nissan, Tamura–Kurata, Heric–Brewer and of Hind et al. Furthermore, apparent molar volume, V¯φ,i and partial molar volume, V¯φ,i0 of amine in cosolvent alcohol in terms of mole fraction concentration unit have been calculated.

The thermodynamic link between excess ultrasound speed, excess molar volume and excess molar isentropic compression of liquid mixtures

A thermodynamic relationship among excess ultrasound speed, excess molar volume and excess molar isentropic compression of liquid mixtures is revisited. The consequences of this relationship, which stems from the Newton–Laplace equation, are discussed. The constraints for possible values taken by Balankina's relative excess properties, that is, ratios between excess and ideal quantities, are further developed. It is demonstrated that, besides the requirement for, if two of these properties attain extreme values at a common exact composition, then the remaining one also takes an extreme value at that composition, further constraints apply to the signs of their rate of change with composition. Using accurate literature data for a binary liquid mixture possessing small positive relative excess molar volumes over the entire composition range, coupled with large positive relative excess ultrasound speeds and large negative relative excess molar isentropic compressions, it is shown that the thermodynamic equations under scrutiny are numerically verified. It is concluded that present theoretical developments can confidently be used for testing the thermodynamic consistency of experimentally determined excess properties of liquid mixtures.

Dimerization model to represent compressibility of alcohol–alkane mixtures

A model assuming that equilibrium reaction of formation of non-compressible dimers dominates in and governs the acoustic properties of liquid mixtures of alcohols in inert hydrocarbon solvents was developed. It was found to describe satisfactorily the observed compressibility dependences on composition of the title systems, in particular those containing long-chained components. This attempt allows to estimate the dimerization equilibrium constants from the compressibility data.

Kirkwood-Buff Analysis of Liquid Mixtures in an Open Boundary Simulation.

Using the adaptive resolution (AdResS) molecular dynamics scheme, we present a new approach to calculate the thermodynamic properties of liquid mixtures in an open boundary simulation. As a test case, we simulate methanol-water mixtures. We show that Kirkwood-Buff integrals (KBI), which directly connect global thermodynamic properties to microscopic molecular distributions, can be efficiently calculated over a wide range of methanol mole fractions by choosing only a very small (∼3% of total simulation domain) open boundary explicit (all atom) region and a surrounding coarse-grained reservoir that takes care of correct particle fluctuations.

Volumetric, Viscometric, and Ultrasonic Properties of Liquid Mixtures of Cyclohexane with Alkanols at Different Temperatures

The densities (ρ), viscosities (η), and ultrasonic speeds (u) of pure cyclohexane, 1-butanol, 2- butanol, and those of their binary mixtures, with cyclohexane as common component, covering the whole composition range have been measured at 293.15, 298.15, 303.15, 308.15, 313.15, and 318.15 K. From the experimental data the excess molar volume (VE), deviations in isentropic compressibility (Δks), deviations in viscosity (Δη), deviations in ultrasonic speed (Δu), deviations in acoustic impedance (ΔZ), deviations in internal pressure (ΔPi), excess Gibbs free energy of activation (ΔG*E), entropies (ΔS*), and enthalpies (ΔH*) of activation of viscous flow have been determined. The sign and magnitude of these parameters were found to be sensitive towards interactions prevailing in the studied systems. Partial molar volumes (V0 φ,2) and partial molar compressibilities (K0 φ,2) of 1-butanol and 2-butanol in cyclohexane have also been evaluated. Moreover, VE values were theoretically predicted by using Flory’s statistical theory. The variations of derived parameters mentioned above with composition offer a convenient method to study the nature and extent of interactions between the component molecules of the liquid mixtures, not easily obtained by other means