Excess Relative Permittivity Research Articles

Density, speed of sound, refractive index and relative permittivity of methanol, propan-1-ol or pentan-1-ol + benzylamine liquid mixtures. Application of the Kirkwood-Fröhlich model

Densities (ρ), speeds of sound (c), relative permittivities at 1 MHz (εr) and refractive indices at the sodium D-line (nD) at T = (293.15 K to 303.15 K) and p = 0.1 MPa are reported for binary liquid mixtures alkan-1-ol + benzylamine. Methanol, propan-1-ol and pentan-1-ol are the alkan-1-ols studied in this work. The values of the excess molar volume (VmE), excess isentropic compressibility (κSE), excess speed of sound (cE), excess refractive index (nDE), excess relative permittivity (εrE) and its temperature derivative (∂εrE/∂T)p are calculated, and they are adjusted to Redlich-Kister polynomials. The VmE values are negative, indicating a predominance of the solvation between unlike molecules and structural effects. εrE values indicate a positive contribution from the creation of (alkan-1-ol)-benzylamine interactions, and the positive value for the methanol mixture emphasises the importance of solvation. Calculations on excess molar refractions point out to weaker dispersive interactions than in the ideal mixture, which may be explained by the mentioned solvation effects. The Kirkwood-Fröhlich model has been applied to the mixtures, and the Kirkwood correlation factors suggest an important relative weight, especially in the methanol system, of linear-like molecules in the solutions, which is in accordance with the positive contribution of the formed multimers to εrE due to their good effective response to the electric field.

Density, speed of sound, refractive index and relative permittivity of methanol, propan-1-ol or pentan-1-ol + aniline liquid mixtures. Application of the Kirkwood-Fröhlich model

Densities (ρ) and speeds of sound (c) at a temperature T = 298.15 K, relative permittivities at 1 MHz (εr) and refractive indices at the sodium D-line (nD) at T = (293.15 K to 303.15 K), all of them at a pressure p = 0.1 MPa, are reported for binary liquid mixtures alkan-1-ol + aniline. The alkan-1-ols considered are methanol, propan-1-ol and pentan-1-ol. Also, the values of the excess molar volume (VmE), excess isentropic compressibility (κSE), excess speed of sound (cE), excess refractive index (nDE), excess relative permittivity (εrE) and its temperature derivative (∂εrE/∂T)p are calculated and fitted to Redlich-Kister polynomials. The agreement among the reported data and other literature sources is analysed by comparing VmE, nDE, εrE and the deviation of c from mole-fraction linearity (Δc). The positive excess molar internal energies at constant volume (Um, VE) show the dominance of the breaking of interactions between like molecules in the energy balance on mixing, particularly the breaking of strong dipolar interactions between aniline molecules. This contribution is also dominant for the εrE values, as they are negative and decrease with the length of the alkan-1-ol chain. Calculations on the concentration-concentration structure factor are consistent with these statements, revealing homocoordination in the studied systems. The VmE are negative, which together with the positive Um, VE indicate the existence of important structural effects in the studied mixtures. The application of the Kirkwood-Fröhlich model shows that the average relative orientation of neighbouring dipoles is similar in the mixtures methanol + aniline or + pyridine, in spite of the different character of the predominant interactions in the latter mixture (heterocoordination).

Dielectric Properties of Binary Solvent Mixtures

Binary solvent mixtures exist as liquids over a wide range of temperatures and pressures. For the rational use of the solvent mixtures it is essential to know their physical properties as functions of their composition and the ambience. The excess functions of physical constants (X(sln)E) can be represented in the polynomial form of the molar fraction (x 2) of the cosolvent by the empirical Redlich-Kister equation.The equation clearly satisfies the condition that X(sln)E is zero at x 2 = 0 and at x 2 = 1. The physical constants of solutions include relative static permittivity, refractive index, viscosity, molar volume, vaper pressure, etc. The relative permittivity reflects the ease with which dielectric polarization proceeds. The relative permittivity is a measure of the solvent’s ability to insulate opposite charges from each other and has a very significant effect on the strength of the interactions between ions especially in dilute solutions. Electrostatic attractions and repulsions between ions are smaller in solvents with higher relative permittivities.We investigated the relative permittivities (ε r(sln)) and excess relative permittivities (ε r(sln)E) of binary mixtures of ethylene carbonate (EC) and a linear carbonate as a function of the composition at 25 ºC. The symbol x 2 denotes the molar fraction of the low-viscosity solvent: 2-fluoroethyl methyl carbonate (2FEMC), ethyl methyl carbonate (EMC), fluoromethyl methyl carbonate (FMMC), or dimethyl carbonate (DMC). EC is a cyclic carbonate, whereas 2FEMC, EMC, FMMC and DMC are linear carbonates. EC and EMC are commonly used as high-polarity and low-viscosity solvents, respectively, for lithium-ion batteries (LIB). Therefore, the relative permittivities of the binary mixtures decrease with an increase in x 2. a 0 is a dominant factor governing ε r(sln)E. a 0 may reflect the difference in the cooperative orientation polarization between the same and different types of dipoles. a 1 and a 2 may represent the difference in the contribution of the two components to the cooperative orientation polarization.The equations of the composition dependence of ε r(sln) and ε r(sln)E fitted experimental data. The ε r(sln) of the EC−2FEMC binary mixture was higher than that of the EC−EMC counterpart. The value of a 0 found in the EC−2FEMC binary solvent system (−49) was less negative than that in the EC−EMC binary solvent system (−51). These findings suggest that the amount of the cooperative orientation polarization of the EC−2FEMC binary mixture is larger than that found for the EC−EMC counterpart. The attraction between EC and 2FEMC molecules can be based on nonconventional weak intermolecular hydrogen bonding (CF−H···O or C−H···F−C). The weak hydrogen-bonding system does not exchange its proton and therefore it is no more a genuine hydrogen bond; it is an electrostatic attraction between positive charge on the hydrogen and negative charge on the organic fluorine or the organic oxygen. The characterization holds also for the EC−FMMC binary solvent system. The value of a 0 found in the EC−FMMC binary solvent system (−32) was also less negative than that in the EC−DMC binary solvent system (−41).The discussion of the composition dependence of ε r(sln) and ε r(sln)E is analogous to a positive deviation from Raoult's law. The positive deviation is characterized by vapor pressures that are higher than those calculated for an ideal solution. The ideal solution would show straight lines in a vapor pressure vs. composition diagram. The escaping tendencies of the components in the solution are accordingly higher than the escaping tendencies in the individual pure liquids. The effect has been ascribed to cohesive forces between unlike components that are smaller than those within the pure liquids, resulting in a trend away from complete miscibility. If the two liquids constituting the mixture are both nonpolar or if both are moderately polar, the positive deviations from ideal behavior are not large. On the other hand, if one component is slightly polar while the other is highly polar, considerable positive deviations may occur.

Studies on the internal structure of the binary mixtures of N,N-dimethylacetamide with 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol and 2-butoxyethanol by means of measuring their densities and relative permittivities at 298.15 K

ABSTRACTThe densities and relative permittivities of binary mixtures of N,N-dimethylacetamide with 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol and 2-butoxyethanol have been measured as a function of composition, at T = 298.15 K. From the experimental data the excess molar volume (VE) from a mole fraction and the excess relative permittivity (εE) from a volume fraction average have been calculated. The results are discussed in terms of intermolecular interactions and structure of studied binary mixtures.

Wavelength-dependent excess permittivity as indicator of kerosene in diesel oil.

Adulteration of diesel oil by kerosene is a serious problem because of air pollution resulting from car exhaust gases. The objective of this study was to develop a relatively simple optical measurement and data analysis method to screen low-adulterated diesel oils. For this purpose, we introduce the utilization of refractive index measurement with a refractometer, scanning of visible-near-infrared transmittance, transmittance data inversion using the singly subtractive Kramers-Kronig relation, and exploitation of so-called wavelength-dependent relative excess permittivity. It is shown for three different diesel oil grades, adulterated with kerosene, that the excess permittivity is a powerful measure for screening fake diesel oils. The excess relative permittivity of such binary mixtures also reveals hidden spectral fingerprints that are neither visible in dispersion data alone nor in spectral transmittance measurements alone. We believe that the excess permittivity data are useful in the case of screening adulteration of diesel oil by kerosene and can further be explored for practical sensing solutions, e.g., in quality inspection of diesel oils in refineries.

Composition Dependence of Physical Constants of Binary Solvent Mixtures

The relative permittivity is a measure of the solvent’s ability to insulate opposite charges from each other and has a very significant effect on the strength of the interactions between ions. We have investigated the relative permittivities, ε r sln, and excess relative permittivities, ε r sln E, of aqueous and nonaqueous mixtures as a function of the composition at 25 ºC. Experimental data were fitted with the Redlich-Kister equation. We found the values of three coefficients (a 0, a 1, and a 2) in the Redlich-Kister equation. We explained the deviation from the ideal solution in terms of the magnitude of the coefficient a 0. a 0 is a dominant factor governing the Redlich-Kister equation. The decrease in a 0 made a plot of ε r sln vs. x 2 close to a straight line, which might correspond to the ideal solution. The cohesive forces between dissimilar components might result in the increased effective dipole moment and, consequently, in the small negative value of a 0. The amount of the cooperative orientation polarization of a water (W)−2,2,2-trifluoroethanol (TFE) binary mixture was larger than that found for a W−ethanol (EtOH) binary mixture. The effective dipole moment of an ethylene carbonate (EC)−dimethyl carbonate (DMC) binary mixture was increased as compared to those found for EC−ethyl methyl carbonate (EMC) and EC−diethyl carbonate (DEC) binary mixtures.

Thermodynamics of amide + amine mixtures. 3. Relative permittivities of N,N-dimethylformamide + N-propylpropan-1-amine, + N-butylbutan-1-amine, + butan-1-amine, or + hexan-1-amine systems at several temperatures

Relative permittivities at 1MHz, εr, and at (293.15–303.15)K, are reported for the binary systems N,N-dimethylformamide (DMF)+N-propylpropan-1-amine (DPA), +N-butylbutan-1-amine (DBA), +butan-1-amine (BA) or +hexan-1-amine (HxA). The values of the excess relative permittivities, εrE, have also been determined for these solutions. The measurements were realized by means of a precision impedance analyser 4294A, to which a 16452A cell connected using a 16048G test lead, all of them from Agilent. The εrE values are large and negative, and diminish when the size of the amine increases along a homologous series, which has been ascribed mainly to the rupture of interactions between like molecules along mixing. Calculations on excess molar orientational polarizabilities support this conclusion, indicating a dominant contribution to εrE from the orientational polarizability of the molecules in the mixture. The analysis of excess relative Kirkwood correlation factors shows that the correlation between dipoles is effectively decreased along the mixing process.

Composition Dependence of Relative Permittivities of Binary Solvent Mixtures

Binary solvent mixtures exist as liquids over a wide range of temperatures and pressures. For the rational use of the solvent mixtures it is essential to know their physical and chemical properties as functions of their composition and the ambience. The excess functions of physical constants (∆X sln E) can be represented in the polynomial form of the molar fraction (x 2) of the cosolvent by the empirical Redlich-Kister equation.The equation clearly satisfies the condition that ∆X sln E is zero at x 2 = 0 and at x 2= 1. The physical constants of solutions include relative static permittivity, refractive index, viscosity, vaper pressure, etc. The relative permittivity reflects the ease with which dielectric polarization proceeds. The relative permittivity is a measure of the solvent’s ability to insulate opposite charges from each other and has a very significant effect on the strength of the interactions between ions especially in dilute solutions. Electrostatic attractions and repulsions between ions are smaller in solvents with higher relative permittivities.We consider a binary solvent mixture containing molecules “1” and “2”. The numbers of the molecules “1” and “2” are N 1 and N 2, respectively. Assuming the tetrahedral quadruplets (ijkl) in a liquid state and the random distribution of the solvent molecules, we have derived the equation of the dependence of relative permittivity (ε r sln) on the composition of a binary solvent mixture. We obtained the coefficients (ai ) of the relative permittivities in the Redlich-Kister equation. a 0 is a dominant factor governing ∆X sln E. a 0 may reflect the difference in the cooperative orientation polarization between the same and different types of dipoles. a 1 and a 2 may represent the difference in the contribution of the two components to the cooperative orientation polarization.We investigated the relative permittivities (ε r sln) and excess relative permittivities (∆ε r sln E) of binary mixtures of ethylene carbonate (EC) and linear carbonate as a function of the composition at 25 ºC. The symbol x 2 denotes the molar fraction of a low-viscosity solvent: 2-fluoroethyl methyl carbonate (2FEMC) or ethyl methyl carbonate (EMC). EC is a cyclic carbonate, whereas 2FEMC and EMC are linear carbonates. EC and EMC are commonly used as high-polarity and low-viscosity solvents, respectively, for lithium-ion batteries.The equations of the composition dependence of ε r sln and ∆ε r sln E fitted experimental data. The ε r sln of the EC−2FEMC binary mixture was higher than that of the EC−EMC counterpart. The value of a 0 found in the EC−2FEMC binary solvent system (−49) was less negative than that in the EC−EMC binary solvent system (−51). These findings suggest that the amount of the cooperative orientation polarization of the EC−2FEMC binary mixture is larger than that found for the EC−EMC counterpart. The attraction between EC and 2FEMC molecules can be based on nonconventional weak intermolecular hydrogen bonding (CF−H···O or C−H···F−C). The weak hydrogen-bonding system does not exchange its proton and therefore it is no more a genuine hydrogen bond; it is an electrostatic attraction between positive charge on the hydrogen and negative charge on the organic fluorine or the organic oxygen.

Separating the contributions of the volume change upon mixing, permittivity contrast and molecular interactions in the excess relative permittivity of liquid mixtures.

The excess relative permittivity of binary systems is separated into three parts. The excess molar volume is the basis for estimating the volume-change contribution. It is proposed to evaluate the electrical permittivity of liquid mixtures, which is solely due to the composition and the relative permittivities of pure components, named permittivity contrast contribution, using the classic local field approach in the case of point-dipoles contained in Lorentz's spherical cavities embedded in the corresponding ideal mixture. The effect of molecular interactions is simply estimated by the difference required to make up experimental excess relative permittivities. This analysis has been applied to 16 binary aqueous organic and organic-organic systems and the estimated values for the contribution of molecular interactions provide interesting insights into the molecular arrangement of these liquid mixtures and the suitability of solvents for determining solute dipole moments.

Relative permittivity, density, viscosity, refractive index and ultrasonic velocity of binary mixture of ethylene glycol monophenyl ether and 1-hexanol at different temperatures

Relative permittivity (ε), refractive index (nD), density (ρ), viscosity (η), and ultrasonic velocity (u) of liquid mixtures of ethylene glycol monophenyl ether and 1-hexanol as a function of mole fraction of 1-hexanol have been measured at three different temperatures (303.15, 313.15 and 323.15K). Various acoustical parameters viz., adiabatic compressibility (β), acoustic impedance (Z), free length (Lf), internal pressure (πi), and free volume (Vf) were evaluated from the experimental data. Excess dielectric, excess physico-chemical and excess acoustic parameters were calculated and fitted to the Redlich–Kister relation. The excess viscosity (ηE), excess relative permittivity (εE) and excess adiabatic compressibility (βE) showed negative deviation from ideality over the entire range of concentration of 1-hexanol. Various excess parameters were qualitatively analyzed to gain some insight to the intermolecular interactions in the liquid mixture.

Static permittivities of n-propanol mixtures with ethanol, isomers of propanol, and butanol at temperature (288.15–308.15) K

The relative static permittivities of six binary systems of n-propanol with ethanol, i-propanol, isomeric butanols are reported as a function of composition at temperatures 288.15 K; 293.15 K; 298.15 K; 303.15 K and 308.15 K. From the experimental results, the excess relative permittivity, ε r E , the permittivity temperature coefficient, ( ∂lnε r / ∂T ), and their excess values at the 298.15 K were calculated. The excess parameters have been fitted to the Redlich–Kister polynomial equation. The results on dielectric measurements were used in the analysis of the hydrogen bond intermolecular interactions occurring between the constituents of alcohol mixture, their dependence on the number of carbon atoms, and the position of the hydroxyl group in the structure of molecules (the type of alcohols). ► Values ε r of mixtures of n-propanol with six alcohols (C1–C4) have been determined. ► Values ε r E , ∂ l n ε r / ∂ T and ∂ l n ε r / ∂ T E at the 298.15 K have been calculated. ► The excess parameters have been fitted to the Redlich–Kister polynomial equation. ► Intermolecular interactions were analyzed.

The permittivity of thermodynamically ideal liquid mixtures and the excess relative permittivity of binary dielectrics

The ideal relative permittivity of liquid mixtures is demonstrated to be a volume-fraction-weighted average of the pure-component relative permittivities. This generalised-thermodynamics result is used to define the molar electric dipole, permittivity, dielectric polarization and electric susceptibility of thermodynamically ideal liquid mixtures and the corresponding excess properties. A hyperbolic approach is developed to the analysis of averaging formulae that are frequently used to predict the effective permittivity of composite materials. Some of these formulae are shown to be segments of rectangular hyperbolae with fixed asymptote values, whereas others can be understood in terms of rectangular hyperbolae with composition-dependent asymptote values. Relative permittivities of binary mixtures between tetraglyme and hexane, cyclohexane or benzene covering the complete composition range are reported at various temperatures. These data are used to outline a novel method for analysing the excess relative permittivity of liquid mixtures.

Studies on Thermodynamic Dissociation Constants of 2,2’-Bipyridine, or 1,10-Phenanthroline in Acetone + Water Mixtures and Gibbs Energy of Transfer of the Hydrogen Ion from Water to Acetone + Water Mixtures

Abstract The thermodyamic dissociation constants for isoelectric reaction of the type LH+ ⇔ L + H+ (where L = 2,2’-bipyridine or 1,10-phenanthroline) have been determined pH-metrically at 298 K in acetone + water mixtures (0-90% of acetone). The pK-values were found to pass through a minimum at about 64-74 Wt% of acetone and then increase. The data are utilized to calculate the Gibbs energies of transfer of the H+ ion from water to acetone + water mixtures from which inferences have been made regarding structural variations and solvent basicity of aquo-organic mixtures. Attempts have been made to understand the basicity and structural properties of acetone + water mixtures from a comparative study of ΔG0 t(H+) profiles, excess relative permittivity εE r(X) and excess Gibbs energy profiles. Acetone has been found to structure forming over the whole composition range and structure formation is maximum in the region 60-70 Wt% of acetone.

Some Physicochemical Properties of Acetonitryle-Methanol Binary Liquid Mixtures

Density and refractive indices for mixtures of acetonitryle with methanol were measured over the whole composition range at 298.15 K, as well as the relative permittivities at 288.15 K, 298.15 K and 308.15 K. From these data the excess molar volumes, apparent and partial molar volumes of acetonitryle and methanol, the excess relative permittivity, the temperature coefficients of relative permittivity and Kirkwood's correlation factor for investigated mixtures were calculated. The 1H-NMR spectra of these liquid binary mixtures, were recorded at 298 K and the spectral parameters, ΔΔ(ACN-MeOH) were calculated. These structural parameters as functions of concentration suggest the formation of the structures such as clathrate and the most stable complexes of the 2 ACN • MeOH and ACN • 3MeOH types.

Dimethylsulfoxide - N,N-Dimethylformamide Binary Mixtures and Their Physicochemical Properties

Density and refractive indices for mixtures of dimethylsulfoxide (DMSO) with N.N-dimethylformamide were measured over the whole composition range at 298.15 K, as well as the relative permittivities at 288.15 K, 293.15 K, 298,15 K, 303,15 K and 308.15K. From these data the excess molar volumes, apparent and partial molar volumes of DMSO and DMF, the excess relative permittivity, the temperature coefficients of relative permittivity and Kirkwood's correlation factor for investigated mixtures were calculated. The 1H-NMR spectra of these liquid binary mixtures, were recorded at 298 K and the spectral parameters, Δδ(DMSO - DMF) were calculated. These structural parameters as functions of concentration suggest the formation of the most stable “complexes” of the 2 DMSO•DMF and DMSO•DMF types.

A Non-Linear Correlation Model for the Relative Permittivity of Ternary Amphiprotic (Solvent) Mixtures

Relative permittivities (є) were determined for ternary ethane-1,2-diol (component 1)/2- methoxyethanol (component 2)/water (component 3) mixtures at five temperatures ranging from 5 to 25°C and over the mole fraction composition range 0 ≤ Xi ≤ 1. The data have been fitted to a model equation that could be useful for predictive є calculations. From the measured є values, the excess relative permittivity єE has been evaluated in order to test for three-component adducts. The values of єE have been found to be negative for all the ternary mixtures under all the experimental conditions, which suggests a strong interaction network through hydrogen bonding, although evidence for a discrete three-component adduct was not forthcoming.

Use of the balanced-cell technique to determine properties of single yeast cells

The dielectrophoretic force on single yeast cells in water has been measured by the method of balancing it against the force of gravity. The force expression for the electrode geometry of parallel wires is derived and related to the electrical properties of the cell and its surroundings through the parameter K, the excess relative permittivity. A detailed analysis is given of the two alternate experimental approaches that can be taken using the balance technique. Experimental values of K are determined for various conditions and compared with those predicted from a theoretical model of a yeast cell.