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The experimental values of densities () and speeds of sound (u) of the binary mixtures of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate [Bmim][BF4] with cyclic amides 2-Pyrrolidinone(2-PY) and N-Vinyl-2-pyrrolidone (NVP) have been used to calculate the internal pressures (i), free volumes (Vf), excess internal pressures (Ei ), excessfree volumes (Ef V), excess free energy (E G), excess enthalpy (E H) and excess entropy (E TS) covering the entirecomposition range expressed by mole fractions of ionic liquid at temperatures (298.15-323.15 K). The results have been interpreted in terms of intermolecular interactions between the component molecules in the mixture. The variations of these excess properties with composition indicate that the interactions between [Bmim][BF4] and cyclic amides in these mixtures follows the order: NVP > 2-PY. [ABSTRACT FROM AUTHOR]

A full complement of standard state thermodynamic properties (ΔfG298.1o, ΔaGT.io, S298.1o and CPo has been determined for a magnesian chamosite [Fe-Chl(W)] and a ferroan clinochlore [Mg-Chl] investigated by calorimetry and low-temperature hydrothermal experiments; this makes these two samples the only natural chlorites whose complete set of thermochemical properties have been reported. ΔfG298.1o for Mg-Chl and Fe-Chl (W) have been determined to be -8161.76 ± 32.50 and -7278.97 ± 21.50 kJ/mol, respectively. Ternary molecular chlorite solid solution modeling approaches have been developed for Al-rich and Si-rich chlorites; unlike available atomic site-mixing chlorite solid-solution models, a molecular model obviates the need for the adoption of a putative structural chemistry. The calculated excess entropy of mixing in the ternary system exhibits a curvilinear dependence on composition and at 25 °C, Gssex vary from about -72 to 413 kJ/mol implying a significant deviation from ideality. The effect of di-trioctahedral substitutions was evaluated by modeling the solid solutions in the quaternary amesite-chamosite-clinochlore-sudoite system for aluminous chlorites; excess functions (Sex, Gex) calculated for these quaternary and ternary solid solutions are marginally different, inherently validating the ternary model. The molecular solid solution model further unmasks significant deficiencies in the available database of standard state thermodynamic properties of chlorites. Finally, pursuant to the recent recognition that green rusts probably play significant roles in the cycling of iron through sedimentary sequences, the neoformation of authigenic iron chlorites from green rusts has been examined; green rusts will readily transform to berthierine and Fe-chlorites except under oxidizing conditions atypical of aquatic environments and ferrugineous sediments. [ABSTRACT FROM AUTHOR]

The density and the viscosity data have been used to determine the thermodynamic activation parameters, free energies (ΔG‡), enthalpies (ΔH‡) and entropies (ΔS‡), for viscous flow of the systems; water (W) + ethylenediamine (ED), W + trimethylenediamine (TMD) and W + N,N-dimethyltrimethylenediamine (DMTMD) in the temperature range of 303.15-323.15 K over the composition range of 0 ≤ X2 ≤ 0.45, where X2 is the mole fraction of diamines. On addition of diamines to water, ΔG‡, ΔH‡ and ΔS‡ values increase sharply, pass through a maximum and then decline. The heights of maximum in the ΔG‡ versus X2 curve vary as, W + DMTMD > W + TMD > W + ED. For all systems, the excess properties, ΔG‡E, ΔH‡E and ΔS‡E are positive. The observed increase in thermodynamic values may be due to combined effect of hydrophobic hydration of diamines and water-diamine interaction as a result of hydrophilic effect. [ABSTRACT FROM AUTHOR]

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]