Non-electrolyte Mixtures Research Articles

Analysis of volumetric properties of liquid mixtures: I. method of binary additive quasi-solvates

The method of binary additive quasi-solvates (BAQS) a new approach for analyzing the physicochemical properties of solutions is proposed. Quasi-solvate Qij is a hypothetical two-particle structure in which one particle i is the ‘solute’ and the other particle j is the ‘solvent’. A set of similar quasi-solvates has the macroscopic property Fij. The solution is an additive mixture of quasi-solvates with weight functions wij. Two models have been developed within the BAQS method: with symmetric weight functions (BAQS/S) and with asymmetric weight functions (BAQS/A). On the example of volumetric properties of non-electrolyte solutions the possibilities of the method are shown. Effective limiting partial molar volumes of components for mixtures of non-electrolytes are determined. The possibility of predicting the properties of multicomponent solutions from data for two-component systems is considered. Applications to other solution properties are shown. Each of the proposed models has its own advantages and limitations. BAQS/S: describes molar volumes of mixtures, especially for aprotonic systems, can be used to predict properties of multicomponent systems, effective on small datasets. Limitations: applicability to other solution properties remains questionable, model parameters differ from those obtained by the independent method, approximation accuracy is inferior to empirical models. BAQS/A: applicable for any solution properties, informative and illustrative. Limitations: very sensitive to the choice of approximating equation, difficult to interpret results, developed only for two-component systems.

Anomalous Concentration Dependence of Surface Tension and Concentration-Concentration Correlation Functions of Binary Non-Electrolyte Solutions.

The concentration dependence of the surface tension of several binary mixtures of non-electrolytes has been measured at 298.15 K. The mixtures have been chosen since they presented a so-called "W-shape" concentration dependence of the excess constant pressure heat capacity and high values of the concentration-concentration correlation function. This behavior was interpreted in terms of the existence of anomalously high concentration fluctuations that resemble those existing in the proximities of critical points. However, no liquid-liquid phase separation has been found in any of these mixtures over a wide temperature range. In this work, we have extended these studies to the liquid-air interfacial properties. The results show that the concentration dependence of the surface tension shows a plateau and the mixing surface tension presents a "W-shape" behavior. To the best of our knowledge, this is the first time that this behavior is reported. The weak anomalies of the surface tension near a liquid-liquid critical point suggest that the results obtained cannot be considered far-from-critical effects. The usual approach of substituting the activity by the concentration in the Gibbs equation for the relative surface concentration has been found to lead to large errors and the mixtures to have a fuzzy and thick liquid/vapor interface.

Why Does Ethaline Apparently Behave as an Ideal Binary Mixture?

Phase diagram mixtures of the salt choline chloride (ChCl) with ethylene glycol (EG) surprisingly seem to behave as ideal binary nonelectrolyte mixtures [Agieienko, V.; Buchner, R. Phys. Chem. Chem. Phys.2022, 24, 5265]. To shed some light on this conundrum, results of broad-band dielectric relaxation spectroscopy (DRS) and quantum-chemical calculations are reported for solutions of ChCl, choline iodide (ChI), and chlorocholine chloride (ClChCl), in EG up to saturation at 298.15 K. The data revealed that all three solutes are only weakly solvated in the sense that on average per equivalent of solute only one EG OH-group is dynamically affected. While contact ion pairs are significant for solute concentrations of ≲1 M, free cation concentrations are rather low. Instead, over the entire concentration range a large fraction of the dipolar cations could not be detected by DRS. We argue that the latter are embedded in large solute aggregates, explaining thus the phase diagram of ChCl + EG and the very low ionicity of all systems.

Use of Thermal Radiation for Remote Identification of Liquids in Closed Dielectric Containers

Remote determination of substances, including liquids, is an urgent problem, the solution of which requires fundamentally new approaches to both methods and measurement techniques. This is due to the fact that standard liquid analysis methods are mainly spectroscopic methods in various frequency ranges from neutron diffractometry to acoustic spectroscopy, which are very difficult or even impossible to apply in remote sensing. Conventional radar methods are usually unacceptable due to the impossibility of covert removal of information using active location and obtaining data on the composition of the irradiated object based on it. Therefore, at present, methods and techniques of passive location are being used more and more, but in order to solve quite specific problems of remote identification of substances, they must be significantly modernized.
 This article discusses a technique and a modernized measuring complex for remote study of liquid electrolytes and non-electrolytes using measurements and subsequent analysis of fluctuations in the temperature difference of the intermediate liquid medium (distilled water) in which the container with the liquid under study is located. To date, there is no clear understanding of how thermally stimulated radiation depends on the composition of a macroscopic body, and also on whether thermal radiation is in equilibrium or non-equilibrium. The investigated object, at a given temperature, emits electromagnetic waves associated with the thermal motion of the molecules and atoms of its constituents. That’s, why thermal radiation is random (fluctuation) process, which means that the average value of the electromagnetic field is equal to zero, but other averaged features, such as quadraticity in the field, may differ from zero. The quadratic characteristics of a thermal electromagnetic field determine its energy, which has a finite value other than zero, which can be measured by an appropriate sensor and characterizes the field source — a macroscopic body heated to a certain temperature. The paper presents the results of studies of mixtures of electrolytes and non-electrolytes of various concentrations. An example of non-equilibrium thermal radiation is given. It is shown that it is possible to distinguish between the studied liquids and methods of combining the components of solutions of given concentrations to obtain the given properties of the entire solution.

Does Pressure Break Mirror-Image Symmetry? A Perspective and New Insights.

This paper is aimed at dissecting and discussing the effect of high pressure on chirogenesis, thus unveiling the role of this universal force in astrochemical and primeval Darwinian scenarios. The first part of this contribution revisits the current status and recent experiments, most dealing with crystalline racemates, for which generation of metastable conglomeratic phases would eventually afford spontaneous resolution and hence enantioenriched mixtures. We then provide an in-depth thermodynamic analysis, based on previous studies of non-electrolyte solutions and dense mixtures accounting for the existence of positive excess volume upon mixing, to simulate the mirror symmetry breaking, the evolution of entropy production and dissipation due to enantiomer conversion. Results clearly suggest that mirror symmetry breaking under high pressure may be a genuine phenomenon and that enantioenrichment from initial scalemic mixtures may also take place.

The Structural Characteristics and Viscosity of Liquids within a Hole Model

Experimental X-ray or electron-diffraction research of liquid allows to reliably assess the size of a lattice seat and holes in quasi-crystalline structures. According to the results of such research, lattice constants for a series of certain n-paraffins were calculated. The author used a hole model of liquids to obtain expressions which were later used to calculate enthalpies of activation of viscous current of n-alkanes and their mixtures. It allowed to connect the experimental work on definition of temperature dependency of liquids viscosity to the calculation of structure properties of liquid mixtures of non-electrolytes. Partly, such calculation was done while solving a problem of the composition of a surface layer of n-alkanes mixtures.

Thermophysical Properties and Phase Behavior of Fluids for Application in Carbon Capture and Storage Processes.

Phase behavior and thermophysical properties of mixtures of carbon dioxide with various other substances are very important for the design and operation of carbon capture and storage (CCS) processes. The available empirical data are reviewed, together with some models for the calculation of these properties. The systems considered in detail are, first, mixtures of carbon dioxide, water, and salts; second, carbon dioxide-rich nonelectrolyte mixtures; and third, mixtures of carbon dioxide with water and amines. The empirical data and the plethora of available models permit the estimation of key fluid properties required in the design and operation of CCS processes. The engineering community would benefit from the further development, and delivery in convenient form, of a small number of these models sufficient to encompass the component slate and operating conditions of CCS processes.

ChemInform Abstract: Physical, Chemical and Structural Effects as Important Factors for the Determination of Thermodynamic and Transport Properties and the Modelling of Non‐Electrolyte Solutions

AbstractReview: 63 refs.

Dynamics of osmosis in a porous medium.

We derive from kinetic theory, fluid mechanics and thermodynamics the minimal continuum-level equations governing the flow of a binary, non-electrolytic mixture in an isotropic porous medium with osmotic effects. For dilute mixtures, these equations are linear and in this limit provide a theoretical basis for the widely used semi-empirical relations of Kedem & Katchalsky (Kedem & Katchalsky 1958 Biochim. Biophys. Acta 27, 229–246 (doi:10.1016/0006-3002(58)90330-5), which have hitherto been validated experimentally but not theoretically. The above linearity between the fluxes and the driving forces breaks down for concentrated or non-ideal mixtures, for which our equations go beyond the Kedem–Katchalsky formulation. We show that the heretofore empirical solute permeability coefficient reflects the momentum transfer between the solute molecules that are rejected at a pore entrance and the solvent molecules entering the pore space; it can be related to the inefficiency of a Maxwellian demi-demon.

Structure and properties of acetone solvates in binary mixtures with some nonpolar solvents

Variations of short-range molecular interactions in acetone-nonpolar solvent systems have been evaluated, and the nature of these variations has been determined in terms of a new continual parameter-free approach to modeling the structure and properties of binary liquid nonelectrolyte mixtures. The results have been obtained by comparing the experimental heats of mixing of acetone with nonpolar solvents with the calculated changes in the energy of solvation in analogous model systems. The theoretical and experimental data suggest formation of azeotrope and demonstrate the effect role of short-range intra- and intermolecular interactions on the azeotrope parameters. No symmetry has been found in the differences between the compositions of solvation shells of acetone molecules and nonpolar counterparts as compared to the solvation shell compositions typical of mixtures formed by only polar or only nonpolar solvents.

The theory of non-electrolyte solutions: an historical review

Starting with the work of van der Waals in 1873, a historical review is given of theories of non-electrolyte mixtures that are based on a well-defined Hamiltonian, and thus can be tested against molecular simulation, as well as experiment. Most of the first 100 years covered here were devoted to attempts to find a successful theory of simple mixtures, culminating in the van der Waals 1-fluid theory of conformal solutions, and perturbation theories based on a hard-sphere reference fluid. The last 40 years has seen the more rapid development of theories for fluids of more complex molecules, including strongly polar liquids, chain molecules and liquids in which molecular association is important. 1 Based on a Molecular Physics Lecture, ‘The Theory of Non-Electrolyte Solutions: A Recent History’, delivered at Imperial College London, 25 September 2009.

The activity of individual ions. A conceptual discussion of the relation between the theory and the experimentally measured values

The difference between the definition of the chemical potential in mathematical terms and its evaluation from experimental data is emphasized. A detailed analysis of the treatments used for mixtures of non electrolytes is used as a guide for the understanding of the treatment required for electrolyte systems. In both cases, the activity coefficients are calculated from data obtained in isothermal closed systems. The perfect analogy between these two cases is demonstrated. Also in both cases, the conditions required for the interpretation of the chemical potential as partial molar property cannot be satisfied experimentally in the measurements. The solution to this apparent impasse is based on a clear distinction between the mathematical and the physical worlds of thermodynamics. Answers are given to the main arguments against the measurement of individual ionic activities.

On the measurement of the real values of individual ionic activities: A chemical engineering perspective

This work demonstrates the perfect analogy between the standard method for determining activities in non-electrolyte mixtures and the method used for the determination of ionic activities in electrolyte solutions. For the case of electrolyte solutions, the general procedure of solving three equations with three unknowns is discussed and the reasons why this procedure failed to work for the case of KCl solutions are recapitulated. A modified iteration procedure implemented in this work gives convergence of the solution after three iterations. The crucial difference between eliminating the junction potential, by combination of independent equations, and the use of a proper estimate of its value is emphasized. A new model-free calibration procedure is proposed and sample calculations of K + and Cl − activities in KCl aqueous solutions are presented. Values of K + and Cl − activities in KCl aqueous solutions obtained by this new procedure and by a variety of other methods and researchers are compared.

New model describing adsorption from liquid binary mixtures of nonelectrolytes with limited and unlimited miscibility of components

Using the thermodynamic idea of complementary systems, and based on fundamental concepts of the theory of volume filling of micropores, we derived a new universal model describing adsorption from solutions with limited and unlimited miscibility of components. The model takes into account the differences in collision diameters of adsorbed molecules as well as the competitive nature of adsorption from solutions. The applicability of this new approach is tested against experimental data.

Prediction of the freezing point of multicomponent liquid refrigerant solutions

The freezing point is one of the most critical properties required to complete the mathematical formulation related to the transport phenomena involved in the immersion chilling and freezing (ICF) of foods. Unfortunately, data for ternary and higher order systems are scarce. The aim of this work was to verify the validity of an excess Gibbs energy model for predicting the freezing point of multicomponent mixtures of electrolytes and non-electrolytes, considering the processing conditions used in immersion chilling and freezing of foods. The extended UNIQUAC model was used. Data obtained from literature corresponding to freezing points of the ternary systems: NaCl–KCl–H2O, NaCl–CaCl2–H2O, NaCl–MgCl2–H2O and NaCl–EtOH–H2O, were compared with predicted values. The model accuracy was satisfactory, the highest absolute deviation being smaller than 1.71°C for the 378 data compared.

The Semi-ideal Solution Theory. 3. Extension to Viscosity of Multicomponent Aqueous Solutions

Viscosities were measured for the ternary aqueous systems NaCl–mannitol(C6H14O6)–H2O, NaBr–mannitol–H2O, KCl–mannitol–H2O, KCl–glycine(NH2CH2COOH)–H2O, KCl–CdCl2–H2O, and their binary subsystems NaCl–H2O, KCl–H2O, NaBr–H2O, CdCl2–H2O, mannitol–H2O, and glycine–H2O at 298.15 K. A powerful new approach is presented for theoretical modeling of the viscosity of multicomponent solutions in terms of the properties of their binary solutions. In this modeling, the semi-ideal solution theory was used to associate the solvation structure formed by each ion and its first solvation shell in a binary solution with the solvation structure of the same ion and its first solvation shell in multicomponent solutions. Then, the novel mechanism proposed by Omta et al. (Science, 301:347–349, 2003) for the effect of a single electrolyte on the viscosity of water was extended to describe the influence of solute mixtures on the viscosity of water, including electrolyte mixtures, nonelectrolyte mixtures, and mixtures of electrolytes with nonelectrolytes. The established simple equation was verified by comparison with measured viscosities and viscosities reported in literature. The agreements are very impressive. This formulation provides a powerful new approach for modeling this transport property in solutions. It can stimulate further research in establishing a dynamical analogue to that formulated for the thermodynamics of multicomponent solutions. It is also very important for the study of hydration of ions.

Influence of the geometric factor on the volume properties of triple mixtures

For model mixtures it is established that the concentration behavior of the molar volume that obeys the additive rule with respect to mole fraction is explained by the difference in geometric structures of pure liquids constituting mixture. It is revealed that the geometric factor (the difference in volumes of molecules and packing densities of the initial liquids constituting mixture) brings significant contribution to the excess molar volume of water mixtures of nonelectrolytes. Within the framework of the suggested approach, a maximum contribution of this factor to the relative excess volume of triple mixtures is estimated.

Preface

Abstract The 20th International Conference on Chemical Thermodynamics (ICCT 2008) was held in Warsaw, Poland, 3-8 August 2008. It was organized jointly by the Institute of Physical Chemistry of the Polish Academy of Science, both Faculties of Chemistry of the Warsaw University of Technology and the Warsaw University, the Polish Chemical Society, and under the auspices of the International Association of Chemical Thermodynamics (IACT). This conference was significant in a line of traditional meetings gathering biennially chemical thermodynamists from all over the world. Almost 300 participants from 39 countries presented 153 oral presentations and 174 posters, among the former ones 12 plenary and 27 invited lectures were given by distinguished researchers. The culminating event was the Rossini lecture given by Prof. Jürgen Gmehling from the University of Oldenburg in Germany, entitled "Present status and potential of group contribution methods for process development". Prof. Gmehling was awarded the prestigious Frederick D. Rossini Award, which has been given biennially to contemporary chemical thermodynamics for an outstanding contribution. Five 2008 IACT Junior Awards were awarded to young scientists for notable achievements presented during the conference in the form of an oral communication. The conference program was grouped into the following symposia: - Molecular simulations of fluid and statistical thermodynamics - Phase equilibria, supercritical fluids, and separation techniques - Electrolyte solutions and non-electrolyte mixtures including reactive chemical systems - Thermodynamics and properties in the biological, medical, pharmaceutical, agricultural, and food sectors - Nanosystems, nanodevices, and advanced materials - Thermochemistry, calorimetry, and molecular energetics - Ionic liquids - Surface and colloid chemistry - Industrial thermodynamics and databases - Thermodynamics frontiers and education - Modulated and oscillation temperature techniques - Environmental thermodynamics This issue of Pure and Applied Chemistry presents 16 papers selected from the plenary and invited lectures delivered at ICCT 2008 with an emphasis on industrial thermodynamics and thermochemistry. We hope that this selection will provide insight into the scientific program of the conference. The 21st International Conference on Chemical Thermodynamics will be held in Tsukuba, Japan, 1-6 August 2010. Tadeusz Hofman Conference Editor

Solid-liquid equilibria of binary systems containing n-tetracosane with naphthalene or dibenzofuran

A differential scanning calorimeter (DSC) was used to determine binary solid-liquid equilibria (SLE) for dibenzofuran+n-C24 and naphthalene+n-C24 mixtures. Results obtained with this technique were compared with those predicted by two modified UNIFAC (Universal Functional group Acitivity Coefficients) versions. This model is employed with the idea to extensively investigate the validity of UNIFAC (Larsen and Gmehling versions). The corresponding activity coefficients were calculated and applied to the prediction of non-electrolyte mixtures real behavior. Reasons of prediction without success in the case of using original interaction parameters, were analysed and discussed. Interesting representation of solubility diagrams was obtained using partly readjusted UNIFAC interaction parameters. The two systems selected can be used for contributing to develop the data base using group contribution methods. For practical purposes, SLE are of interest in chemical process design, especially when process conditions must be specified to prevent precipitation of a solid.

Prediction of heat capacity, density and freezing point of liquid refrigerant solutions using an excess Gibbs energy model

Immersion chilling and freezing (ICF) of foods use aqueous solutions at low temperature that are considered secondary refrigerants. These solutions contain solutes such as NaCl, CaCl 2, KCl, ethanol, glucose, etc. The ICF processes have several advantages over the conventional food chilling and freezing methods. The aim of this work was to study the behavior of an excess Gibbs energy model for predicting thermodynamic properties of mixtures of electrolytes and non-electrolytes, considering the physical conditions used in immersion chilling and freezing of foods. The extended UNIQUAC model was used. Data obtained from literature for heat capacity, density and freezing point for binary aqueous solutions of NaCl, CaCl 2, KCl and ethanol were compared with predicted values. Additional parameters for the density estimation were included into the model. In general, the model accuracy was satisfactory.