The Thermodynamic Properties of Mixtures of Small, Nonpolar Molecules

Estimation of Ultrasonic Velocity, Density, Internal Pressure, and Thermophysical Parameters of Ionic Liquid Mixtures: Application of Flory's Statistical Theory

Flory's statistical theory (FST) has been employed to estimate the ultrasonic velocity, density, internal pressure, and several important thermophysical parameters such as the energy of vaporization, the heat of vaporization, cohesive energy density, polarity index, and solubility for eight binary mixtures of ionic liquids and water within the temperature range of 288.15 to 308.15 K. The ionic liquids chosen for this investigation are [BMim][dca], [BMim][TfO], [BMpy][TfO], [BMpyr][dca], [BMpyr][TfO], [EEPy][ESO4], [HMim][dca], and [MPy][MSO4]. The predicted values of ultrasonic velocity and density show good agreement with the data reported in the literature. It endorses the applicability of FST to these binary mixtures. A comparative analysis of the internal pressure values (Pi) determined by using FST and the standard thermodynamic approach is also presented. The results obtained for Pi using both approaches show good agreement. Besides, for the mixtures under study, the correlation between ultrasonic velocity, density, and surface tension has also been examined. The variation of thermophysical parameters with concentration and temperature changes has been utilized to explore the nature and strength of the solute-solvent interactions prevalent in these mixtures. It is pointed out that A-A-type interactions dominate over A-B-type interactions in water-rich regions of the mixtures.

Measurement and Modelling of Excess Molar Volume and Excess Enthalpy of n-tridecane or n-tetradecanewithdecalin By Application of PFP Theory.. [DOI: 10.21203/rs.3.rs-3175305/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

The experimental measurement of density and enthalpy of mixture for two binary liquid mixtures of n-tridecane or n-tetradecane with decalin was reported in this paper. The measurements were conducted at a temperature range of 293.15 to 323.15K and at 303.15K using calorimeter C80. The mixtures were analyzed at various proportions, including the entire composition range and infinitely diluted. The excess molar volume (VE) and excess molar enthalpy (HE) of mixtures were calculated and fitted using the Redlich-Kister equation. The paper observed the expansion phenomenon for the VE at all temperatures, including over the entire composition range and infinitely diluted. Additionally, the HE exhibited endothermic behavior at the studied temperature range and composition range. The Prigogine-Flory-Patterson (PFP) theory was utilized to predict both thermodynamic properties, namely the VE and HE. The results obtained using the PFP theory were compared with those obtained using the Treszczanowicz and Benson association (TB) model for VE and with the NRTL, Wilson, and Flory models for HE. The PFP model, which employed a single fitted parameter to describe VE, demonstrated satisfactory performance in predicting VE. Conversely, the Treszczanowicz and Benson association (TB) model yielded relatively poor results in fitting VE. However, the NRTL, Wilson, PFP, and Flory models exhibited good performance in predicting HE.

Entropy determination for mixtures in the adiabatic grand-isobaric ensemble

The entropy change that occurs upon mixing two fluids has remained an intriguing topic since the dawn of statistical mechanics. In this work, we generalize the grand-isobaric ensemble to mixtures and develop a Monte Carlo algorithm for the rapid determination of entropy in these systems. A key advantage of adiabatic ensembles is the direct connection they provide with entropy. Here, we show how the entropy of a binary mixture A–B can be readily obtained in the adiabatic grand-isobaric ( μA, μB, P, R) ensemble, in which μA and μB denote the chemical potential of components A and B, respectively, P is the pressure, and R is the heat (Ray) function, that corresponds to the total energy of the system. This, in turn, allows for the evaluation of the entropy of mixing and the Gibbs free energy of mixing. We also demonstrate that our approach performs very well both on systems modeled with simple potentials and with complex many-body force fields. Finally, this approach provides a direct route to the determination of the thermodynamic properties of mixing and allows for the efficient detection of departures from ideal behavior in mixtures.

Novel Binary Mixtures of Alkanolamine Based Deep Eutectic Solvents with Water—Thermodynamic Calculation and Correlation of Crucial Physicochemical Properties

This paper demonstrates the assessment of physicochemical and thermodynamic properties of aqueous solutions of novel deep eutectic solvent (DES) built of tetrabutylammonium chloride and 3-amino-1-propanol or tetrabutylammonium bromide and 3-amino-1-propanol or 2-(methylamino)ethanol or 2-(butylamino)ethanol. Densities, speeds of sound, refractive indices, and viscosities for both pure and aqueous mixtures of DES were investigated over the entire range of compositions at atmospheric pressure and T = (293.15 ‒ 313.15) K. It was concluded that the experimental data were successfully fitted using the Jouyban–Acree model with respect to the concentration. Obtained results showed that this mathematical equation is an accurate correlation for the prediction of aqueous DES properties. Key physicochemical properties of the mixtures—such as excess molar volumes, excess isentropic compressibilities, deviations in viscosity, and deviations in refractive indices—were calculated and correlated by the Redlich–Kister equation with temperature-dependent parameters. The non-ideal behavior of the studied systems were also evaluated by using the Prigogine−Flory−Patterson theory and the results were interpreted in terms of interactions between the mixture components.

Binary mixtures of semicrystalline polymers with low-molecular-mass compounds: thermal behaviour and phase structure

The results of phase equilibrium studies in mixtures of semicrystalline polymers with low-molecular-mass compounds are summarized and analyzed. A new classification of phase diagrams for such mixtures is proposed. Alternative points of view on the phase composition of semicrystalline polymers are presented. The phase structure evolution during the thermally induced phase separation of mixtures is monitored and the morphology of the forming capillary porous bodies as precursors of polymeric membranes is described. The general regularities concerning the influence of the nature of mixture components, polymer molecular mass, temperature scanning rate and other factors on the topology of phase diagrams are considered. Experimental methods used to construct the phase diagrams of mixtures and to study features of their phase structure are compared.

The bibliography includes 203 references.

Prediction of Internal Pressure of Binary Liquid Mixtures Using Flory's Statistical Theory

Internal pressures of a number of binary liquid mixtures of varying natures of component liquids have been predicted using Flory's statistical theory. The predicted values have been compared with the experimentally calculated ones. Good approximation has been observed.

Application of Flory's Statistical Theory for the Estimation of Internal Pressure of the Liquid Mixtures

Flory's Statistical Theory has been employed for the evaluation of internal pressure of liquid mixtures at varying conditions. The method used for the evaluation does not use any empirical relation, unlike the approaches of previous workers. The computed values have been compared against the values obtained from thermodynamic relation taken as an experimental method. To the best of our knowledge, the present approach has not been employed previously by any worker. The excellent agreements between the computed and experimental values prove the applicability of this approach for the evaluation of internal pressure in liquid mixtures.

Prediction of density of liquid mixtures using Flory's statistical theory†

Density of various binary and multicomponent liquid mixtures have been calculated with the help of Flory's statistical theory at different temperatures. Computed values of densities have been compared with the experimental values. Excellent agreement has been found.