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Densities (ρ), speeds of sound ( u), and isentropic compressibilities ( k S) of binary mixtures of dimethyl sulfoxide (DMSO) with water, methanol, ethanol, 1-propanol, 2-propanol, acetone and cyclohexanone have been measured over the entire composition range at 293.15 and 313.15 K. The excess molar volumes ( V E), the deviations in speed of sound ( u E) and the deviations in isentropic compressibility ( k S E) have been determined. The V E, u E and k S E values were fitted by the Redlich-Kister polynomial equation and the A k coefficients as well as the standard deviations ( d) between the calculated and experimental values have been derived. The results obtained are discussed from the viewpoint of the existence of interactions between the components of the binary mixtures. [ABSTRACT FROM AUTHOR]

Surface tensions ( σ) and densities ( ρ) of 4-methyl-2-pentanone/ethyl benzoate binary mixtures have been measured over the entire composition range at 278.15, 288.15, 298.15, and 308.15 K. Values of the excess surface tensions ( σE) and excess molar volumes ( VE) have been calculated. The σE and VE values were fitted by to the Redlich–Kister polynomial equation and the A k coefficients have been derived. The standard deviations between the calculated and the experimental excess properties have also been derived. The surface tension values have been further used to calculate the surface entropies ( SS) and surface enthalpies ( HS) per unit surface area. The lyophobicity ( β) and the surface mole fractions ( x1S) of the surfactant 4-methyl-2-pentanone have been derived using the extended Langmuir model. The obtained results are discussed from the viewpoint of the existence of specific interactions between unlike molecules in the bulk region and the surface. [ABSTRACT FROM AUTHOR]

Isothermal vapour-liquid equilibrium data at 333·15 K and excess molar volumes of mixing at 298·15K for the binary mixtures of ethylenediamine with isomeric butanols were measured over the entire mole fraction range. The values of molar excess free energy, G , and excess volumes, V , are negative for all the four systems, indicating strong specific interactions between two unlike molecules. The branching of the alkyl chain of alcohol also affects the excess properties considerably. [ABSTRACT FROM AUTHOR]

The effect of change in alkyl chain and the branching of the alkyl chain of alcohol on the interactions with amine has been studied. For this purpose, the three excess properties, viz., free energy of mixing, enthalpy of mixing and volume change on mixing have been studied. The vapour liquid equilibrium of n-butylamine 1-propanol,-1-butanol,-2-propanol,-2-butanol systems were studied at 55°C The four systems show negative deviation from Raoult's Law. The heats of mixing of n-butylamine with 2-propanol and 2-butanol determined at 25°C show that both the systems are strongly exothermic because of amine-alcohol complex formation. The volume change on mixing of the four earlier mentioned systems were determined at 25°C, and is found to be negative for all the four systems, with the maxima at 0·5 mol fraction. Increase in the alkyl chain length of alcohol does not change the excess properties while the branching of the alkyl chain considerably affects all the excess properties. [ABSTRACT FROM AUTHOR]

Differential scanning calorimetry (DSC) is used to investigate the thermal properties of N-(2-ethanol)-p-nitroaniline + N-(2-acetoxyethyl)-p-nitroaniline, and their binary systems. The experimental results demonstrate that the studied binary system presents a simple eutectic behavior and the corresponding mole fraction (xeu) of N-(2-ethanol)-p-nitroaniline at the eutectic point is 0.5486, whereas the temperature (Teu) is found to be equal to 363.6 K. The quality of the solid-liquid equilibria (SLE) data has been checked by thermodynamic consistency tests, presenting good quality factor. The SLE data have been correlated by means of Wilson, NRTL, and UNIQUAC equations. The three models describe satisfactorily the phase diagram as the root-mean-square deviations for the equilibrium temperatures vary from 1.25 K to 2.07 K. Nevertheless, the Wilson model provides the best correlation results. The three equations have also been used to compute excess thermodynamic functions viz. excess Gibbs energy, enthalpy and entropy. The obtained results revealed a sensitive positive deviation to ideality thus demonstrating the nature of the interactions between the compounds forming the mixture. Microstructural studies have been carried out by FTIR, XRD and optical microscopy showing weak molecular interactions for the eutectic mixture. [ABSTRACT FROM AUTHOR]