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Four binary mixtures with potential for stabilizing energetic materials have been investigated. The phase diagrams of N-(2-methoxyethyl)-p-nitroaniline + diphenylamine, N-(2-methoxyethyl)-p-nitroaniline + N-(2-acetoxyethyl)-p-nitroaniline, N-(2-methoxyethyl)-p-nitroaniline + 2-nitrodiphenylamine, and N-(2-methoxyethyl)-p-nitroaniline + 1,3-diethyl-1,3-diphenylurea have been determined by differential scanning calorimetry. All systems display a simple eutectic behavior. Consistency tests have been applied to inspect the quality of the SLE data, showing very satisfactory quality factors. The SLE data have also been correlated by Wilson and NRTL models. The employed equations calculated the equilibrium temperatures with a root mean square deviations varying from 1.37 to 2.29 K. These models have been applied to compute the excess thermodynamic functions as well, giving highly comparable values for a further qualitative and quantitative analysis. The results show a positive deviation from ideality for all the investigated systems due to the dominant effect of the self-association molecules. The XRD studies revealed the existence of weak interactions between the components in the formed eutectics and suggested that they are mechanical systems. • The four investigated mixtures are simple eutectic. • The quality of the SLE data has been checked by consistency tests. • The Wilson and NRTL models correlate accurately the SLE data. • Excess thermodynamic functions allow highlighting the nature and the intensity of the existing interactions. • XRD results showed that the eutectics are mechanical systems. [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 ability to extract thermodynamic properties of mixtures from molecular geometry and interactions is one of the major advantages of atomistic simulations, but, at the same time, can be a great challenge, especially for statistical properties such as the Gibbs energy of mixing (Δ mix G ). This challenge becomes even greater in the case of mixtures of complicated molecules or macromolecules. Kirkwood-Buff theory offers a promising avenue for estimating Δ mix G from atomistic simulation of binary mixtures. In this work we perform molecular dynamics simulations of both ideal and real binary Lennard-Jones mixtures at various mole fractions. We estimate the Kirkwood-Buff integrals by two different methods and identify the most efficient one. Then we validate our methodology by comparing several thermodynamic properties of the ideal mixtures against the theoretical expressions of thermodynamics. Finally, we calculate the mixing thermodynamic properties for the real mixtures, namely the enthalpy, Gibbs energy, volume, and entropy of mixing, as well as their excess parts relative to an ideal solution. We compare our results against the predictions of the well-known modified Benedict-Webb-Rubin equation of state for Lennard-Jones systems and find good agreement. [ABSTRACT FROM AUTHOR]

To explore the type of interaction and its behavior with temperature in the binary mixture (dimethyl carbonate + benzyl benzoate), the density ( ρ ) and speed of sound ( u ) are measured for the whole mole fraction range at various temperatures T = (308.15, 313.15 and 318.15) K and at atmospheric pressure. Sign with magnitude of computed excess molar volume ( V m E ) was examined and detailed analysis elucidated not only prevalence of strong molecular interactions between molecules in study but also its variation with temperature. Further, strong interactions are well supported by partial and their excess partial molar volume ( V ¯ m , V ¯ m E , V ¯ m E , ∞ ). Furthermore, relative association ( R A ), Lennard-Jones repulsive power ( n ), excess isentropic compressibility ( κ s E ), partial and their excess partial molar isentropic compressibility( K ¯ m , K ¯ m E ), excess values of isobaric thermal expansion coefficient ( α P E ), isentropic compressibility ( κ s E ), isothermal compressibility ( k T E ), intermolecular free length ( L f E ), acoustic impedance ( Z E ), surface tension ( σ S E ), ultrasonic speed ( u E ) were evaluated and confirmed the conclusions made for V m E . By Redlich-Kister equation, coefficients with standard deviations are computed to excess parameters. V m E is correlated by Prigogine–Flory–Patterson (PFP) and Topology theories at 308.15 K. Extended Langmuir model is examined for influence of the bulk mole fraction on surface tension. At T = 308.15 K, different derivatives of thermodynamic potentials, densities through Soave-Redlich-Kwong (SRK)/Peng-Robinson (PR) cubic equation of states, excess chemical potential and theoretical speeds using semi-empirical equations are evaluated. Using Hartmann–Balizar and Ballou non-linear equations, cohesive energy ( ΔA ), van der Wall's constants ( a , b ), distance of closest approach ( d ) are estimated through Sehgal's equations at all temperatures. [ABSTRACT FROM AUTHOR]

In this work, the sophisticated thermodynamic techniques: thermodynamic and thermophysical properties of binary mixtures of 1-ethyl-3-methylimidazolium [C 2 mim][MeSO 4 ] with various organic solvents were determined at different temperatures and under ambient pressure. Experimental densities and speed of sound of binary systems of IL with 1-alcohols: 1-heptanol, 1-octanol or 1-nonanol were measured at temperature range from (25 to 35) 0 C. The excess molar volumes ( V E ) and excess isentropic compressibilities ( κ s E ) were derived using the experimental data. The positive to negative V E values were observed for the systems [C 2 mim][MeSO 4 ] with 1-heptanol or 1-octanol whereas the only positive V E values for the 1-nonanol system. Negative κ s E values obtained for the systems [C 2 mim][MeSO 4 ] with 1-heptanol or 1-octanol except higher composition of 1-octanol and positive κ s E values for the 1-nonanol system at all temperatures. A discussion was carried out in terms of interactions and structure factors in these binary mixtures based on results obtained. [ABSTRACT FROM AUTHOR]

The densities, ρ and speeds of sound, u of the binary mixtures of 2-pyrrolidone with 1,2-propanediol and 1,3-propanediol, including those of pure liquids, have been measured over the entire range of composition at temperatures, (303.15–323.15) K and atmospheric pressure. Using the experimental data, excess molar volumes, V m E , excess isentropic compressibility, κ s E , excess speeds of sound, u E and excess molar isentropic compressibility, K s,m E were calculated. The partial molar volumes, V ¯ m, 1 and V ¯ m, 2 , partial molar isentropic compressibilities, K ¯ s,m, 1 and K ¯ s,m, 2 , excess partial molar volumes, V ¯ m, 1 E and V ¯ m, 2 E and excess partial molar isentropic compressibilities, K ¯ s,m, 1 E and K ¯ s,m, 2 E over whole composition range; partial molar volumes, V ¯ m, 1 ° and V ¯ m, 2 ° , partial molar isentropic compressibilities, K ¯ s,m, 1 ° and K ¯ s,m, 2 ° , excess partial molar volumes, V ¯ m, 1 ° E and V ¯ m, 2 ° E and excess partial molar isentropic compressibilities, K ¯ s,m, 1 ° E and K ¯ s,m, 2 ° E of the components at infinite dilution have also been calculated. The results have been discussed in terms of intermolecular interactions prevailing in these mixtures. The results indicated that the interactions in these systems follow the order: 1,2-propanediol > 1,3-propanediol. The speeds of sound of these mixtures have been analysed by using scaled particle theory and the results are compared with experimental findings. [ABSTRACT FROM AUTHOR]

The molecular interactions in the binary mixtures of benzylalcohol (BnOH) with ethylacetate (EA), n-propylacetate (PA) and n-butylacetate (BA) have been analyzed using the experimental densities ( ρ ) and speeds of sound ( u ) over the whole range of composition at T = (298.15, 303.15, 308.15 and 313.15) K under atmospheric pressure. From the measured density and speed of sound data, the excess volumes ( V E ), excess isentropic compressibilities ( κ s E ), excess partial molar volumes ( V i ¯ E ) and excess partial molar volumes at infinite dilution ( V ¯ i E , ∞ ) for the said binary mixtures have been computed. The studied excess thermodynamic properties for the binary mixtures were found to be negative over the entire range of composition and at all the specified temperatures. The results have been interpreted in terms of formation of the intermolecular hydrogen bonds between component molecules, interstitial accommodation and structural factors ensuing in the binary mixtures. Further, Redlich-Kister and Hwang equations were fitted to the excess functions in order to derive the fitting parameters. Moreover, the experimental speed of sound data was correlated with two theoretical models namely free length theory (FLT) and collision factor theory (CFT). In addition, the experimental excess volumes ( V E ) have been used to test the applicability of the Prigogine–Flory–Patterson (PFP) theory to the studied binary mixtures. Likewise, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectra for these binary systems have been recorded at equimolar composition to elucidate the intermolecular hydrogen bonding between component molecules. A good correlation is observed between excess thermodynamic parameters and ATR-FTIR studies. [ABSTRACT FROM AUTHOR]

Thermodynamic behavior of aqueous solutions of two ionic liquids (ILs), [EMIM][SCN] and [EMIM][DCA], was thoroughly characterized. Vapor–liquid equilibria (water activity), mixing enthalpy, density, and viscosity were systematically measured in the entire composition range and/or specifically in the highly dilute IL region, as a function of temperature in the range from (288.15 to 318.15) K. Pertinent information available in the literature was gathered and critically examined. Data on system energetics, measured in this work and selected from the literature, were simultaneously correlated with an NRTL-type model. Despite complicated courses of excess energetic functions, their compact, thermodynamically consistent and adequate representation was achieved and the model description was proved to provide reasonable extrapolations. Excess volumes (positive) and viscosity deviations (negative) as functions of composition and temperature were correlated with Padé approximants with T -dependent parameters yielding adequate representation of data even for the M-shaped curves encountered for the excess volume of (water + [EMIM][SCN]). The aqueous solutions of [EMIM][SCN] and [EMIM][DCA] were found to exhibit a closely similar energetic behavior. Both systems display large negative excess Gibbs energy and S-shaped excess enthalpy and excess heat capacity which are positive in the IL dilute region and change to negative and close-to-zero, respectively, as the IL content increases. The inferred excess entropy is markedly positive, reflecting vast disorganization of nano-scale structures upon mixing the ILs with water. A detailed inspection of the energetic functions of the two systems revealed consistently more positive values for [EMIM][SCN] indicating that [DCA] − is slightly more hydrophilic anion than [SCN] − . Comparison to [EMIM][tricyanomethanide] studied previously showed that [DCA] − and [SCN] − are considerably more hydrophilic than [TCM] − . [ABSTRACT FROM AUTHOR]

The properties of fluoride in wet phosphoric acid processes were of interest us to understand the processes and roles that fluorosilicic acid plays in phosphoric acid solutions. The literature data indicate that some deficiencies exist in the thermodynamic properties of hexafluorosilicic acid aqueous solutions. In this investigation, the water activity and osmotic coefficients of H 2 SiF 6(aq) were determined in the temperature range from T = 298.15 to 353.15 K. The measurements of the water activity were performed at molalities from 0.10 to 3.00 mol kg −1 of H 2 SiF 6(aq) using the hygrometric method. The modelling approach based on the Pitzer model was developed to determine the thermodynamic properties. From these measurements, the ion interaction parameters in binary solution were evaluated at different temperatures ranging from 298.15 K to 353.15 K and were used to predict the solute activity coefficients. The development of a model for solution behaviour was also employed to determine the excess molal Gibbs energy, enthalpy, entropy and heat capacity of the H 2 SiF 6 aqueous solution within the temperature range from 298.15 K to 353.15 K. [ABSTRACT FROM AUTHOR]

Abstract: The coefficient of compressibility, k =ΔV/V o , of {water (1)+ethylene glycol (2)} binary mixture was measured at pressures from 0.1 to 100MPa and temperatures from 278.15 to 323.15K over the whole concentration range. At all state parameters the following characteristics were calculated: excess molar volumes of the mixture, ; changes of excess molar Gibbs energy, ; changes of excess molar entropy, ; changes of excess molar enthalpy, ; mixing enthalpy, , of water with ethylene glycol at high pressure, and partial molar volumes of the components. It was shown that the coefficients of compressibility, k, sharply decreased over the concentration interval x 2 =0–0.2, where x 2 was ethylene glycol mole fraction, and further changed insignificantly. It was revealed that excess molar volumes were negative at all temperatures studied and went down with pressure increasing. The dependence of partial molar volumes of the mixture components on ethylene glycol mole fraction passes extreme at all isobars. Limiting partial molar volumes of water and ethylene glycol decrease with pressure growth. The mixture compression leads to its ordering due to new hydrogen bonds formation. [Copyright &y& Elsevier]

Abstract: Surface force measurements conducted with thiolated gold surfaces showed previously that hydrophobic interaction entails a decrease in excess film entropy, suggesting that hydrophobic force originates from changes in the structure of the medium (water) confined between hydrophobic surfaces [1]. As a follow-up work, surface force measurements have been conducted in the present work using an atomic force microscope (AFM) with silica surfaces coated with octadecyltrichlorosilane (OTS) at temperatures in the range of 10–40°C. A thermodynamic analysis of the results show that both the excess film entropy (ΔS f) and excess film enthalpy (ΔH f) decrease with decreasing thickness of the water films between the hydrophobic surfaces. It has been found also that |ΔH f|>|TΔS f|, which represents a necessary condition for the excess free energy change (ΔG f) to be negative and hence the hydrophobic interaction be attractive. Thus, the results obtained with both the thiolated and silylated surfaces show that hydrophobic forces originate from the structural changes in the medium. It is believed that the water molecules in the thin liquid films (TLFs) of water form clusters as a means to reduce the free energy when they cannot form H-bonds to neighboring hydrophobic surfaces. [Copyright &y& Elsevier]

Abstract: Densities and speed of sound were measured for six binaries and three ternary liquid systems. Excess acoustical and its allied properties like excess internal pressure, excess thermal pressure coefficient, excess pseudo-Gruneisen parameter, excess speed of sound and excess ultrasonic impendence, were evaluated with the help of perspective of two liquid models i.e. Prigogine–Flory–Patterson (PFP) and Bertrand–Acree–Bruchfield (BAB) at 298.15 K over a wide range of composition. The results so obtained from two liquid models are very much comparable and are in good agreement. A molecular interaction study has also been made successfully in the light of these excess acoustical properties. [Copyright &y& Elsevier]

Abstract: The high-pressure phase diagram and excess thermodynamic properties of the binary mixture of carbon dioxide and water are examined using the statistical associating fluid theory for potentials of variable range (SAFT-VR). The carbon dioxide molecule is modelled with two tangentially bonded spherical segments, while the water molecule is modelled as spherical with four associating sites to represent the hydrogen bonding. Dispersion interactions are modelled using square-well potentials. The optimised intermolecular parameters are taken from the works of Galindo and Blas [F.J. Blas, A. Galindo, Fluid Phase Equilib. 194–197 (2002) 501–509; A. Galindo, F.J. Blas, J. Phys. Chem. B 106 (2002) 4503–4515] and Clark et al. [G.N.I. Clark, A.J. Haslam, A. Galindo, G. Jackson, Mol. Phys. 104 (2006) 3561–3581] for carbon dioxide and water, respectively. The mixture exhibits type III phase behaviour in the classification of Scott and van Konynenburg, with the gas–liquid critical line continuously changing into a liquid–liquid line at high pressures. In this work one unlike intermolecular interaction parameter is fitted to give the best possible representation of the minimum temperature of the gas–liquid critical line of the mixture, and is then used in a transferable manner to study other thermodynamic conditions and properties. The phase diagrams predicted by the SAFT-VR approach are found to be in very good agreement with the experimental data at low and high pressures and temperatures. In addition, a good qualitative description of the excess molar volume and excess enthalpy and different temperatures and pressures is obtained. [Copyright &y& Elsevier]

Abstract: Densities (ρ), speeds of sound (u), isentropic compressibilities (k s), refractive indices (n D), and surface tensions (σ) of binary mixtures of methyl salicylate (MSL) with 1-pentanol (PEN) have been measured over the entire composition range at the temperatures of 278.15K, 288.15K, and 303.15K. The excess molar volumes (V E), excess surface tensions (σ E), deviations in speed of sound (Δu), deviations in isentropic compressibility (Δk s), and deviations in molar refraction (ΔR) have been calculated. The excess thermodynamic properties V E, σ E, Δu, Δk s, and ΔR were fitted to 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 surface tension (σ) values have been further used for the calculation of the surface entropy (S S) and the surface enthalpy (H S) per unit surface area. The lyophobicity (β) and the surface mole fraction of the surfactant component PEN have been also derived using the extended Langmuir model. The results provide information on the molecular interactions between the unlike molecules that take place at the surface and the bulk. [Copyright &y& Elsevier]

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]

Abstract: Densities (ρ), surface tensions (σ), and absolute viscosities (η) of binary mixtures of N,N-dimethylformamide (DMF) with toluene have been measured over the entire composition range at the temperatures (278.15, 283.15, and 293.15)K. The excess molar volumes (V E), the excess surface tensions (σ E), the deviations in viscosity (Δη), and the excess free energies of activation of the viscous flow (ΔG ∗E) have been calculated. The excess thermodynamic properties V E, σ E, Δη, and ΔG ∗E were fitted to the Redlich–Kister polynomial equation, and the A k coefficients as well as the standard deviations between the calculated and experimental values have been derived. The surface tension values have been further used to calculate the surface entropy (S S) and surface enthalpy (H S) per unit surface area. The lyophobicity (β) and the surface mole fraction of the surfactant toluene have been also derived using the extended Langmuir model. The results obtained are discussed from the viewpoint of the existence of interactions between the components in the bulk and the surface. [Copyright &y& Elsevier]

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]

Infinite dilution activity coefficients and gas-to-liquid partition coefficients are herein reported for more than 45 organic solutes of varying polarity and hydrogen-bonding character dissolved within the ether-grafted ionic liquids 1-ethyl-3-(2-methoxyethyl)imidazolium bis(trifluoromethylsulfonyl)imide and N -(2-methoxyethyl)pyridinium bis(trifluoromethylsulfonyl)imide. Experimental values were determined in 10 K intervals from 323.15 to 373.15 K using the method of inverse gas chromatography. Measured infinite dilution activity coefficients were then used to determine the partial molar excess Gibbs free energies, enthalpies, and entropies associated with the dissolution of these model solutes into these two short-chain glycol-grafted ionic liquids. Finally, based on the measured infinite dilution activity coefficient data, Abraham model correlations have been established for solute transfer into these ionic liquids, including the calculation of cation-specific equation coefficients. The derived Abraham model correlations were found to back-calculate the observed partition coefficients to within 0.09 to 0.13 log units. • Infinite dilution activity coefficients determined for organic solutes dissolved in 2 ILs • Gas-to-IL partition coefficients determined for organic solutes dissolved in 2 ILs • Excess thermodynamic properties reported for organic solutes dissolved in 2 ILs • Abraham model correlations derived for describing solute transfer into 2 ILs [ABSTRACT FROM AUTHOR]

Infinite dilution activity coefficients and gas-to-liquid partition coefficients are reported for >40 organic solvents dissolved in (2-methoxyethyl) triethylphosphonium bis(trifluoromethylsulfonyl)imide, (2-methoxyethyl)tributylphosphonium bis(trifluoromethylsulfonyl)imide, and (2-methoxyethyl)triethylammonium bis(trifluoromethylsulfonyl)imide in the temperature range from 323.15 K to 373.15 K. Experimental values were determined using the method of inverse gas chromatography. Measured infinite dilution activity coefficients are used to calculate the partial molar excess Gibbs free energy, enthalpy and entropy associated with dissolution of the organic solutes into the three ionic liquid solvents. Abraham model correlations for solute transfer into each ionic liquid solvent have also been determined from the measured infinite dilution activity coefficient data. • Infinite dilution activity coefficients measured for solutes in three new glycol-functionalized ionic liquids. • Gas-to-liquid partition coefficients determined for solutes in these glycol-functionalized ionic liquids. • Abraham model correlations reported for solute transfer into these glycol-functionalized ionic liquids. [ABSTRACT FROM AUTHOR]