Viscosity,refractive index,and surface tension of multicomponent systems: Mathematical representation and estimation from data for binary systems

An equation previously developed for estimation of the excess thermodynamic properties of multicomponent systems from binary mixing data has been applied to other physical properties through extrathermodynamic properties such as the excess Gibbs free energy of activation for viscous flow, molar refractivity, and exess surface free energy. This equation provides reasonably accurate predictions for viscosity, refractive index and surface tension of ternary and quaternary systems, given the properties of the various binary combinations of the components. The equation also serves quite well as a point-of-departure for mathematical representation of experimental data, in that all of the data considered could be represented within experimental uncertainty with the aid of no more than one adjustable parameter for each multicomponent system.     

Thermodynamic excess properties of ternary alcohol-hydrocarbon systems. Simplified method for predicting enthalpies from binary data

Two general equations for estimation of excess enthalpies of ternary systems consisting of an alcohol and two hydrocarbons from observed excess properties of the various binary combinations have been developed. The first expression is based on the Kretschmer-Wiebe association model and takes the form $$\Delta \overline H _{ABC}^{ex} = h_A x_A K_A (\phi _{A1} - \phi _{A1}^o ) + Q_{ABC}$$ where $$\begin{gathered} Q_{ABC} = (x_A + x_B )(\phi _A + \phi _B )(\Delta \overline H _{AB}^{ex} )_{phys}^ \bullet + (x_A + x_C )(\phi _A + \phi _C )(\Delta \overline H _{AC}^{ex} )_{phys}^ \bullet \hfill \\ + (x_B + x_C )(\phi _B + \phi _C )(\Delta \overline H _{BC}^{ex} )_{phys}^ \bullet \hfill \\ \end{gathered}$$ \((\Delta \overline H _{ij}^{ex} )_{phys}^ \bullet\) represents the physical interactions in each of the individual binary systems, and the term involving φ _A1 ^o represents the chemical contributions (caused by self-association) to the excess enthalpies of mixing. The second predictive expression is based on the Mecke-Kempter association model and is given by $$\Delta \overline H _{ABC}^{ex} = - h_A x_A [In(1 + K_A \phi _A )/K_A \phi _A - In(1 + K_A )/K_A ] + Q_{ABC}$$ where the first term (contained within brackets) represetns the chemical contributions to the enthalpies of mixing. The predictions of both expressions are compared with experimental data for the excess enthalpies of six ternary systems.     

The prediction of vapor-liquid equilibrium data from heat of mixing data for three non-ideal binary systems

The method of Hanks et al. was used with the heat of mixing data of McFall et al. for 1,3-butadiene + propylene, 1-butene + methyl tert.-butyl ether, and carbon disulfide + methanol to predict the vapor-liquid equilibrium behavior for these systems. The method involves curve-fitting an excess enthalpy model derived from an excess Gibbs energy model by means of the Gibbs-Helmholtz equation to the heat of mixing data, determining the adjustable parameters from this fit, and using the original excess Gibbs function equation to predict the vapor-liquid equilibrium behavior. The predicted vapor-liquid equilibrium values were compared with experimental values and good agreement was found.     

The use of the NRTLmKW model for predicting VLE data of binary systems from the excess enthalpy data

A new local composition model NRTLmKW has been used for correlation of 15 binary excess enthalpy data. The data, binary systems formed by hydrocarbons and alkanols, have been selected to give a wide representation of various kinds molecular interactions in solution. Further the model, basing on the results of the correlation, has been used for prediction of excess enthalpy and VLE (vapour-liquid equilibria) in these systems. The obtained results have been discussed from the point of view of intermolecular interactions and some recommendations have been made on the use of the NRTLmKW model for such calculation.     

Thermodynamics of binary mixtures: excess volumes of mixing of some binary 1,2-dichloroethane mixtures

The excess volumes, V^E, of some binary 1,2-dichloroethane mixtures have been determined at 30°C. The data have been examined for Cell model theory of Prigogine and Flory's theory. Both theories have been found to fail to fit the results with useful accuracy.     

Topological and thermodynamic investigations of binary mixtures: Molar excess volumes, molar excess enthalpies and isentropic compressibility changes of mixing

Molar excess volumes, V^E, molar excess enthalpies, H^E, and speeds of sound, u, of o-toluidine (i) + cyclohexane or n-hexane or n-heptane (j) binary mixtures have been determined over entire range of composition at 308.15 K. Speeds of sound data have been utilized to predict isentropic compressibility changes of mixing, of (i + j) mixtures. The observed V^E, H^E and data have been analyzed in terms of Graph theory. The analysis of V^E data by Graph theory reveals that o-toluidine exists as an associated molecular entity and (i + j) mixtures contain 1:1 molecular complex. It has been observed that V^E, H^E and values calculated by Graph theory compare well with their corresponding experimental values. The observed data have also been analyzed in term of Flory theory.     

Qualitative analysis of excess dielectric properties of binary mixtures, ternary mixtures and mixing dynamics measurement using surface plasmon resonance

The analysis of the excess dielectric properties for various binary mixtures and a ternary mixture is demonstrated using a surface plasmon resonance (SPR) sensor. Strong deviations from ideality are seen using SPR to monitor deviations in the dielectric properties following mixing. Binary mixtures with similar refractive index were measured: hexanes/isopropanol, n-heptanes/propanol, 1-acetoxy-2-methoxyethane/2-methoxyethanol, butanol/dipropylamine, hexanes/ethylacetate, and ethylacetate/isopropanol binary mixtures. The ternary mixture was composed of 60 different proportions of hexanes, isopropanol, and ethylacetate. Using SPR, mixing dynamics is easily accessible. The mixing of hexanes and isopropanol in static solution was monitored.     

The prediction of isobaric phase equilibria for non-ideal multicomponent mixtures from heat of mixing data

A method for predicting isobaric binary and ternary vapor—liquid equilibrium data using only isothermal binary heat of mixing data and pure component vapor pressure data is presented. Three binary and two ternary hydrocarbon liquid mixtures were studied. The method consists of evaluating the parameters of the NRTL equation from isothermal heat of mixing data for the constituent binary pairs. These parameters are then used in the multicomponent NRTL equation to compute isobaric vapor—liquid equilibrium data for the ternary mixture. No ternary or higher order interaction terms are needed in the ternary calculations because of the nature of the NRTL equation. NRTL parameters derived from heat of mixing data at one temperature can be used to predict vapor—liquid equilibrium data at other temperatures up to the boiling temperature of the liquid mixture.For the systems studied this method predicted the composition of the vapor phase with a standard deviation ranging from 1–8% for the binary systems and from 4–12% for the ternary systems.     

The estimation of the thermodynamic properties of ternary alloys from binary data using the shortest distance composition path

A new composition path, X_i-X_j=constant, is suggested for the semi-empirical calculation of the thermodynamic properties of ternary ‘substitutional’ solutions from binary data, when the binary systems show deviations from the regular solution model. A comparison is made between the results obtained for integral and partial properties using this composition path and those calculated employing other composition paths suggested in literature. It appears that the best estimate of the ternary properties is obtained when binary data at compositions closest to the ternary composition are used.     

Interpretation of flow data for multicomponent polymeric systems

A model based on the altered free volume state concept has been proposed here to predict the melt flow index values of multicomponent systems as a function of the amount of the dispersed phase. The predictions of the model have been compared with experimental results reported in the literature on a diverse range of multicomponent polymeric systems. The agreement between the model predictions and the experimentally determined values is good.     

Retention in liquid chromatography with multicomponent mobile phases: Relationship with binary systems

Summary Using the concept of an effective concentration a method is proposed for predicting retention in liquid chromatography with multicomponent mobile phases based on experiments with corresponding binary ones. The method is verified for normal and reversed-phase systems with ternary mobile phases and agrees closely with experimental data.     

Effect of NaCl on the excess enthalpies of binary liquid systems

The excess molar enthalpies h^E₁₊₂₃ of ethanol+(water+NaCl), benzylalcohol+(water+NaCl), and cyclohexane+(methanol+NaCl) were measured at 298.15 K, those of methanol+(water+NaCl) at 298.15 and 323.15 K. An LKB flow microcalorimeter was used and a special flow-mix cell was developed with regard to the corrosive electrolyte solutions. Knowing the integral enthalpy of solution and the solution enthalpy at infinite dilution for a salt (3) in a solvent (2), the molar excess enthalpy h^E₁₂₃ can be calculated.     

Thermodynamics of associated solutions: New expressions for the excess Gibbs free energy and excess enthalpy of mixing of alcohol-solvent systems

This article presents new equations based on a continuous linear association model used by Kretschmer and Wiebe. The new equations are used to reduce experimental vapor-liquid equilibrium and excess enthalpy of mixing data for solutions of alcohols and active solvents. The new equations give an excellent representation of the experimental results and are able to predict equilibrium data for ternary alcohol-solvent systems with good accuracy.     

Phase equilibria and excess properties for binary systems in reactive distillation processes Part I. Methyl acetate synthesis

Isothermal vapor–liquid equilibrium (VLE) and excess enthalpy (H^E) data were measured for binary systems required for the design of reactive distillation processes for the methyl acetate production. The isothermal P–x data were measured with the help of a computer-operated static apparatus. A commercial isothermal flow calorimeter was used for the determination of the heats of mixing. Temperature-dependent interaction parameters for the UNIQUAC model were fitted simultaneously to the experimental data from this work and other authors.     

Thermochemical data of barium peroxide from thermogravimetric measurements

Decomposition temperatures of barium peroxide in equilibrium with the oxygen pressure in the gas phase have been determined by thermogravimetric measurements at temperatures from 670 to 843. Enthalpies and entropies of the reaction BaO₂= =BaO+0.5O₂ and of the formation of BaO₂ have been calculated.

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Zusammenfassung Zersetzungstemperaturen von mit dem Sauerstoffdruck in der Gasphase in Gleichgewicht stehendem Bariumperoxyd wurden thermogravimetrisch im Temperaturbereich von 670 bis zu 843 ermittelt. Enthalpie- und Entropiewerte der Reaktion BaO₂= =BaO+0.5 O₂ und der Bildung von BaO₂ wurden errechnet.

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Résumé On a déterminé les températures de décomposition du peroxyde de baryum en équilibre avec la pression d'oxygène de la phase gazeuse, par mesures thermogravimétriques entre 670 et 843. On a calculé les enthalpies et les entropies correspondant à la réaction BaO₂=BaO+0.5 O₂ et à la formation de BaO₂.

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, , , 670 843. BaO₂= + +0.5 O₂ BaO₂.

     

Prediction of vapor-liquid equilibrium from excess enthalpy data for binary ether +n-alkane or cyclohexane mixtures

Vapor liquid equilibrium (VLE) is successfully predicted from excess enthalpy H^E data for binary ether + n-alkane or cyclohexane mixtures. Parameters for the continuous linear association model (CLAM) and for the UNIQUAC Model for the excess Gibbs energy G^E were determined from H^E data measured at a low temperature (ambient temperature). These parameters are used to predict VLE data at low and high temperatures. The dependence of the accuracy of predictions on the set of H^E data chosen to evaluate the parameters and on the model for G^E are discussed.     

Azeotropic line determination from the caloric data on binary stratifying systems

The experimental isochoric heat capacity values of stratifying n-hexane-water mixtures of the compositions 0.120, 0.166, 0.200, and 0.256 H₂O mole fractions were obtained using a high-temperature adiabatic calorimeter over the density ranges 244.74–498.25, 121.06–438.21, 252.02–500.00, and 208.11–398.88 kg/m³, respectively. The C _{V, x} heat capacities were tabulated for the mixture with 0.120 H₂O mole fractions. Liquid-liquid and liquid-gas phase equilibrium curves were plotted. The suggestion was made that the intersection point between these curves characterized the state of an azeotrope. The azeotropic line with the critical point at its end was constructed.     

An analytic model for the excess properties of binary liquid mixtures

A model has been devised to analyse excess property data for binary liquid mixtures. The model embodies the concept of the segmentation of the total composition range into three distinct regions. Results are given for the analyses of Δ$\text{V}$, Δ$\text{H}$ and Δν for the acetonitrile-water and dimethylsulfoxide-water systems.     

Thermodynamics of weak interactions: excess enthalpies and excess Gibbs free energies of mixing

Excess enthalpies of chloroform + n-hexane, bromoform + n-hexane, bromoform + pyridine and bromoform + benzene and excess Gibbs free energies of mixing for bromoform + pyridine, chloroform + pyridine, bromoform + n-hexane, chloroform + n-hexane and bromoform + benzene have been determined at 308.15 K and the same factors have been examined for Barker's theory to understand the magnitude and nature of various interactions between the components of these mixtures.