Excess enthalpies of 2-propanol + cyclohexane and 2-propanol + benzene + cyclohexane at 298.15 K

With an isothermal dilution calorimeter excess enthalpies have been determined at 298.15 K for 2-propanol + cyclohexane and 2-propanol + benzene + cyclohexane mixtures. The results are fitted with an associated-solution model. Predicted excess enthalpies for the ternary mixture agree well with the experimental results.     

Excess enthalpies of binary and ternary mixtures of acetonitrile with methanol,ethanol and benzene

Excess molar enthalpies are measured for the binary mixtures methanol—acetonitrile and ethanol—acetonitrile at 25 and 35°C and for the ternary mixtures methanol—acetonitrile—benzene and ethanol—acetonitrile—benzene at 25°C using an isothermal dilution calorimeter. The binary results are well reproduced with an association model which contains four equilibrium constants for the association of alcohol, two equilibrium constants for that of acetonitrile, and two solvation equilibrium constants between alcohol and acetonitrile molecules. The ternary results are compared with those calculated from the model with binary parameters.     

Excess functions of (an alkane + carbon disulphide) at 298.15 K

Vapour pressures, excess enthalpies, and densities for {(1?x)C₆H₁₄ + xCS₂} {(1?x)C₁₀H₂₂ + xCS₂}, {(1?x)C₁₃H₂₈ + xCS₂}, and {(1?x)C₁₆H₃₄ + xCS₂} have been measured at 298.15 K. It was found that H_m^E and V_m^E increase as chain length increases while G_m^E diminishes, becoming negative for hexadecane.     

Excess enthalpies of (methyl propanoate or methyl pentanoate + 1-alkanol) at 298.15 K

The excess molar enthalpies H_m^E of methyl propanoate or methyl pentanoate + 1-butanol, + 1-hexanol, + 1-octanol, and + 1-decanol have been determined experimentally at 298.15 K using a Calvet microcalorimeter. For all these mixtures H_m^E > 0; the values increase with the chain length of the alkanol but decrease as the ester chain lengthens.     

Excess heat capacities of binary mixtures of carbon tetrachloride with n-alkanes at 298.15 K

A Picker flow microcalorimeter was used to determine molar excess heat capacities C_P^E at 298.15 K for mixtures of carbon tetrachloride + n-heptane, n-nonane, and n-decane. The excess heat capacities are negative in all cases. The absolute value |C_P^E| increases with increasing chain length of the alkane. A formal interchange parameter, c_P12, is calculated and its dependence on n-alkane chain length is discussed briefly in terms of molecular orientations.     

Excess heat capacities and excess volumes of binary liquid mixtures of chloroform with cyclic ethers at 298.15 K

Molar excess heat capacities at constant pressure, C^E_p, of binary liquid mixtures chloroform + oxolane, chloroform + 1,3-dioxolane, chloroform + oxane, and chloroform + 1,4-dioxane have been determined at 298.15 K from measurements of volumetric heat capacities in a Picker flow microcalorimeter. A precision of ±0.04 J K^?1 mole^? was achieved by using the stepwise procedure. Experimental molar excess heat capacities are compared with values derived from H^E results at different temperatures. Excess molar volumes, V^E, for the same systems at 298.15 K have been determined by measuring the density of the pure liquids and solutions with a high-precision digital flow densimeter.     

Molar excess enthalpies of ternary mixtures of non-electrolytes

Molar excess enthalpies, H^E_ijk(T₁, x_i, x_j), for methylenebromide (i)+pyridine (j)+β-picoline (k); pyridine (i)+β-picoline (j)+cyclohexane (k); benzene (i)+toluene (j)+1,2-dichloroethane (k); benzene (i)+o-xylene (j)+1,2-dichloroethane (k); and benzene (i)+p-xylene (j)+1,2-dichloroethane (k) mixtures have been measured calorimetrically as a function of temperature and composition. The data have been analysed in terms of the Sanchez and Lacombe theory and using an approach employing the “graph theoretical” concept of connectivity parameters to characterize its pure components. It has been observed that the H^E_ijk (T, x_i, x_j) data calculated from the “graph theoretical” approach using ³ξ values based on δ^v considerations (that take into consideration the valency of individual atoms of the molecular graph constituent components) best reproduces the corresponding experimental H^E_ijk data.     

Molar excess volumes and molar excess enthalpies of methylenebromide + aromatic hydrocarbon mixtures

Molar excess volumes V^e and molar excess enthalpies H^e of binary methylenebromide (i) +benzene. +toluene, and + o^?, + m^? and + p-xylene (j) mixtures have been determined at 298.15 and 308.15 K. The data have been analysed in terms of recent approaches for solutions of nonelectrolytes, and the results suggest that these mixtures are characterised by specific interactions between the components. Self-volume interaction coefficients V_iiV_jj have also been evaluated.     

Excess molar volumes of (ethyl formate or ethyl acetate + an isomer of hexanol) at 298.15 K

Excess molar volumes V_m^E were determined over the entire composition range at 298.15 K for ethyl formate or ethyl acetate + hexan-1-ol, +2-methylpentan-1-ol, +3-methylpentan-2-ol, +2-methylpentan-3-ol, +3-methylpentan-3-ol, +2-methylpentan-2-ol, +4-methyl-pentan-2-ol, and +hexan-2-ol. Excess volumes were determined from density measurements made with a vibrating-tube densimeter. The V_m^E values were all positive, decreasing with the n value of the ester: C_n?1H_2n?1CO₂C₂H₅.     

Infrared matrix isolation evidence for the formation of (η5-cyclopentadienyl)tricarbonyl-molybdenum and -tungsten radicals in carbon monoxide matrices at 12 K

Infrared spectroscopic evidence including ¹³CO labelling and energy-factored force-field fitting is presented for the first time to show that the radicals (η⁵-C₅H₅)-M(CO)₃^? (M = MO, W) and HCO are produced on photolysis of (η⁵-C₅H₅)M(CO)₃H complexes in CO matrices at 12 K.     

Liquid-liquid extraction: A graphical method for equilibrium stage calculations for quaternary systems

Ruiz Beviá, F., Prats Rico, D. and Marcilla Gomis, A.F., 1984. Liquid-liquid extraction: a graphical method for equilibrium stage calculations for quaternary systems. Fluid Phase Equilibria, 15: 257-265.A very simple graphical method for stage calculations has been developed for quaternary systems. The calculation method is based on the equilibrium representation method proposed by Ruiz and Prats (1983a), and requires only two graphs for solution of the material balances. The method is based completely on experimental data and does not require any simplifying hypotheses.     

Enthalpy of solution of KCl and NaCl in water at 298.15 K

The enthalpies of solution of KCl and NaCl in water at 298.15 K have been measured as a function of molality in a heat-flux calorimeter of the Tian-Calvet type built in our laboratory. The covered range is 0.01 to 0.06 mol·kg^?1 for KCl and 0.01 to 0.11 mol·kg^?1 for NaCl. An accurate electrical calibration has been done. Also, the quantitative influence of each of several experimental factors has been analysed. The experimental results have been compared with the available values from several authors. Finally, the enthalpies of solution at infinite dilution for KCl and NaCl at 298.15 K have been obtained.     

The phase diagram for the binary system K2CrO4CaCrO4

The phase diagram for the binary system K₂CrO₄CaCrO₄ has been determined for CaCrO₄ concentrations up to 60 mole%, using the techniques of differential thermal analysis, X-ray diffraction, and drop calorimetry. Essential features of the phase diagram are: the solid-solid phase transition for pure K₂CrO₄ at 670°C, β-K₂CrO₄ ? α-K₂CrO₄; a eutectoid reaction at 14 mole% CaCrO₄ and 548°C, β-K₂CrO₄ ? α-K₂CrO₄ + K₂CrO₄ · CaCrO₄; a peritectoid event at 50 mole% CaCrO₄ and 640°C, β-K₂CrO₄ + CaCrO₄ ? K₂CrO₄ · CaCrO₄; and a eutectic reaction at 51 mole% CaCrO₄ and 678°C, L ? β-K₂CrO₄ + CaCrO₄. X-ray diffraction studies lead to the determination of the unit cell dimensions for the K₂CrO₄ · CaCrO₄ double salt, a C-centered monoclinic form with a₀ = 7.615(6) Å, b₀ = 22.797(15) Å, c₀ = 9.777(9) Å, β = 115.45(5)°.     

Model selection for complex systems involving polynuclear species

1-hydroxyethylidene-1,1-bisphosphonic acid (HEDP) is a phosphonate chelate with several diagnostic and therapeutic applications. Previous studies have indicated that calcium complex aggregation occurs in the basic range of pH; results from this study indicate that complex aggregation occurs throughout the physiological range of pH as well. Calcium complex formation data were used for PQ analyses and plots of the derivative of Z with respect to total diphosphonate at constant free calcium ion concentration were shown to provide valuable information with regard to model selection. A link-addition stepwise complex formation model was shown to be most appropriate; a robust feature of all aggregate formation models examined is a strong pH dependence of polynuclear complex formation in the pH range 5.5–7.0.     

Vapor—liquid equilibria for the ternary Ethanol—2-butanone—benzene system at 298.15 K

Vapor—liquid equilibrium data for the ternary ethanol—2-butanone—benzene system and its constituent binary systems at 298.15 K are presented. The results are correlated with the Wilson, original and modified UNIQUAC equations and the UNIFAC group contribution method.     

The thermodynamic properties of acetals+heptane mixtures at 298.15 K

Excess enthalpies and excess volumes were determined at 298.15 K for: dimethoxymethane+heptane, diethoxymethane+heptane, 1,1-dimethoxyethane+heptane, 1,1-diethoxyethane+heptane, 2,2-dimethoxypropane+heptane and 1,1-diethoxypropane+heptane.