N. Ouerfelli

Viscosity Arrhenius Activation Energy and Derived Partial Molar Properties in 1,4-Dioxane + Water Binary Mixtures from 293.15 to 323.15 K

The knowledge and prediction of physicochemical properties of binary liquid mixtures is of great importance for understanding intermolecular interactions. Viscosities (η) have been investigated by using density (ρ) and kinematic viscosity (ν) measurements for 1,4-dioxane + water (D–W) mixtures over the entire range of mole fractions under atmospheric pressure, at 311.15, 316.15 and 320.15 K, in order to increase the studied temperatures range available from the literature and to improve the investigations. The viscosity Arrhenius activation energy of 1,4-dioxane + water mixtures was calculated from the present experimental viscosity measurements, and those presented in a previous work at only four temperatures, and for three temperatures in the present work, over the entire range of composition in the temperatures range from 293.15 to 323.15 K. Based on the partial molar activation energy from the Arrhenius equation for viscosity, interactions between water and 1,4-dioxane molecules are discussed. Comparison between some reduced Redlich–Kister functions covering the composition domain shows the existence of two distinct behaviors.

A shear viscosity study of cerium (III) nitrate in concentrated aqueous solutions at different temperatures

Kinematic viscosities and densities of in aqueous solutions, from pure water to very concentrated solutions, were determined at different temperatures. Shear viscosity data for this asymmetrical 3:1 electrolyte were calculated. For the low concentrations , the Jones - Dole coefficients A and B were determined for this rare-earth salt by fitting the quadratic behaviour of the square root of the molar concentration with the least-squares method. At concentrations above 1 mol , the logarithm of viscosity can be fitted by a third-order polynomial, where the coefficients exhibit a linear dependence on the reciprocal of the absolute temperature. This phenomenon is due to the strong ion - solvent correlation.

Competition between Redlich–Kister and improved Herráez equations of correlation viscosities in 1,4-dioxane +water binary mixtures at different temperatures

Viscosity deviation Δη has been investigated by using density and kinematic viscosity measurements for dioxane + water mixtures over the entire range of mole fractions at atmospheric pressure and in five temperatures (293.15, 298.15, 302.15, 306.15 and 309.15 K). This system exhibited very large positive values of due to increased hydrogen bounding interactions between unlike molecules in the cluster formation region and to very large differences between the molar volumes of the pure components. The results were fitted with the Redlich–Kister equations and the recently proposed Herráez equation. This last model was improved by fixing the first constant of the corresponding exponential function. Competition between the two models at different parameter numbers is discussed. We note that, in this system, where the viscosity versus molar fraction of dioxane presents a maximum, experimental data are in agreement with the two models when more than three parameters are employed.

A New Equation Relating the Viscosity Arrhenius Temperature and the Activation Energy for Some Newtonian Classical Solvents

In transport phenomena, precise knowledge or estimation of fluids properties is necessary, for mass flow and heat transfer computations. Viscosity is one of the important properties which are affected by pressure and temperature. In the present work, based on statistical techniques for nonlinear regression analysis and correlation tests, we propose a novel equation modeling the relationship between the two parameters of viscosity Arrhenius-type equation, such as the energy () and the preexponential factor (). Then, we introduce a third parameter, the Arrhenius temperature (), to enrich the model and the discussion. Empirical validations using 75 data sets of viscosity of pure solvents studied at different temperature ranges are provided from previous works in the literature and give excellent statistical correlations, thus allowing us to rewrite the Arrhenius equation using a single parameter instead of two. In addition, the suggested model is very beneficial for engineering data since it would permit estimating the missing parameter value, if a well-established estimate of the other parameter is readily available.

The relative reduced Redlich–Kister equations for correlating excess properties of N,N-dimethylacetamide + 2-methoxyethanol binary mixtures at temperatures from 298.15 K to 318.15 K

Knowledge and prediction of physicochemical properties of binary mixtures is of great importance for understanding intermolecular interactions. The literature shows that most such systems exhibit non-linear behaviour. Excess molar volumes, viscosity deviations and isentropic compressibility changes in N,N-dimethylacetamide + 2-methoxyethanol binary mixtures at 298.15, 308.15 and 318.15 K were calculated from experimental density, viscosity and sound velocity data presented in previous work. Here these experimental values were used to test the applicability of the correlative reduced Redlich–Kister equation and the recently proposed Herráez equation as well as their corresponding relative functions. Their correlation ability at different temperatures, and the use of different numbers of parameters, is discussed for the case of limited experimental data. These relative functions are important to reduce the effect of temperature and, consequently, to reveal the effects of different types of interactions. Limiting excess partial molar volume at infinite dilution were deduced from different methods, activation parameters and partial molar Gibbs energy of activation of viscous flow against compositions were investigated. The results of these observations have been interpreted in terms of structural effects of the solvents. In this frame, a correlating equation is recently proposed by Belda and in order to assess the validity of the proposed equation, it has also been applied to the present system for molar volume properties.

The reduced Redlich–Kister excess molar Gibbs energy of activation of viscous flow and derived properties in 1,4-dioxane + water binary mixtures from 293.15 to 309.15 K

The excess molar volume, viscosity deviation and excess Gibbs free energy of activation of viscous flow have been investigated from the density and shear viscosity measurements of water–dioxane mixtures over the entire range of mole fractions from 293.15 to 309.15 K. The results were fitted by the Redlich–Kister equation. Partial molar volume and Gibbs energy at infinite dilution were deduced from four methods, activation parameters and partial molar Gibbs energy of activation of viscous flow against compositions were investigated. The water–dioxane interactions have principally an H-bound character and there are two principal types’ structures limited by 0.08 mole fraction in dioxane. The reduced Redlich–Kister excess properties provide an indication of the intermolecular interactions and for dioxane–water cluster formation as suggested in the literature.

Treatment of Herráez equation correlating viscosity in binary liquid mixtures exhibiting strictly monotonous distribution

Recently, Herráez et al. proposed a new correlation equation, which introduces a correcting polynomial as an exponential-acting upon the molar fraction of one of mixture components. This equation is found to be widely applicable with more reasonable accuracy in systems exhibiting monotonous distribution than those presenting an extremum. In previous works, we have found that the first adjustable parameter of this equation is a universal exponent (0.5 or 1) for dioxane–water and isobutyric acid–water mixtures characterising the presence of solute–solute or solute–solvent interaction at very high dilution. In this work, we have tested this equation in 48 systems, and we have noted that several data on binary mixtures exhibiting monotonous variation are well represented by the two sides of this equation. We have mathematically justified the four distinct values of the universal exponent classifying the nature of each solute–solvent couple in dilute region.

Validity of the correlation–Belda equation for some physical and chemical properties in isobutyric acid + water mixtures near and far away from critical temperature

Knowledge and prediction of physicochemical properties of binary mixtures is of great importance for understanding intermolecular interactions. The literature shows that most of such systems exhibit non-linear behaviour. In this frame, a correlating equation with two parameters is recently proposed by Belda and tested with success for about of 50 binary systems for density, viscosity, surface tension and refractive index. In order to assess the validity of the proposed equation, the latter has been applied to isobutyric acid + water mixtures (at 300.15 or 301.15 and 308.15 K) for seven physicochemical properties. These mixtures exhibit strong correlations and interactions, especially near the critical composition and temperature. Experimental results are compared with those fitted with the proposed equation in the light of the corresponding correcting factor. On the whole, the Belda equation seems to offer satisfactory results for some properties even near critical temperature when interaction and correlation length between molecules increases.

Viscosity Arrhenius activation energy and derived partial molar properties in of N,N-dimethylacetamide + 2-ethoxyethanol binary mixtures at temperatures from 298.15 K to 318.15 K.

Calculation of excess properties in N,N-dimethylacetamide + 2-ethoxyethanol binary mixtures at (298.15, 308.15 and 318.15) K from experimental density, viscosity and sound velocity values were presented in previous work. Applications of these experimental values to test different correlation equations as well as their corresponding relative functions were also reported. Considering the quasi-equality between the Arrhenius activation energy Ea and the enthalpy of activation of viscous flow ∆H*, here we can define partial molar activation energy Ea1 and Ea2 for N,N-dimethylacetamide and 2-ethoxyethanol, respectively, along with their individual contribution separately. Correlation between the two Arrhenius parameters of viscosity in all the domains of composition shows the existence of two main distinct behaviours separated by a stabilised structure in a short range of mole fraction in N,N-dimethylacetamide from 0.14 to 0.45. We add that correlation reveals interesting Arrhenius temperature, which is closely related to the vaporisation temperature in the liquid vapour equilibrium.

Investigations of the reduced Redlich–Kister equations for correlating excess properties of N,N-dimethylacetamide + 2-ethoxyethanol binary mixtures at temperatures from 298.15 K to 318.15 K

Excess molar volumes, viscosity deviations and isentropic compressibility changes in N,N-dimethylacetamide + 2-ethoxyethanol binary mixtures at (298.15 K, 308.15 K and 318.15 K) were calculated from experimental density, viscosity and sound velocity data presented in previous work. Here these experimental values were used to test the applicability of the correlative reduced Redlich–Kister equation and the Herraez equation as well as their corresponding relative functions. These relative functions are important to reduce the effect of temperature and, consequently, to reveal the effects of different types of interactions. Limiting excess partial molar volume were deduced from different methods, activation parameters and partial molar Gibbs energy of activation of viscous flow against compositions were investigated. The results of these observations have been interpreted in terms of structural effects of the solvents. The correlating equation recently proposed by Belda, has also been applied to the present system in order to assess the validity of this equation.