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Complexes of the divalent metal ions, Ca2+ and Zn2+ with the bio-relevant α-amino acids, l-cysteine and glycine were investigated by means of the potentiometric technique. The dissociation constants of the bio-ligands were determined and used for determining the stability constants of their binary and ternary complexes formed in aqueous solutions at 25 ± 0.1 °C and constant ionic strength of 0.20 mol·dm−3 NaNO3. The acid–base properties of glycine were investigated at different ionic strengths, ranging from 0.01 to 0.30 mol·dm−3 NaNO3 at 25.0 ± 0.1 °C. The concentration distribution of the different glycine species formed in solution due to variation of pH was evaluated and discussed. The formation of the different 1:1 and 1:2 binary complexes and 1:1:1 ternary complexes were inferred from the potentiometric pH-metric titration curves. The ternary complex formation occurred in a stepwise manner with l-cysteine acting as the primary ligand. The stability constants of these binary and ternary complex systems were evaluated. The ∆log10K values, percentage of relative stabilization (%R.S.) and log10X for the ternary complexes were evaluated and are discussed. [ABSTRACT FROM AUTHOR]

Densities of the ternary system dimethyl carbonate + butyl methacrylate + allyl methacrylate and its binary subsystem butyl methacrylate + allyl methacrylate have been measured in the whole composition range, at 293.15 K and atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess molar volumes of the binary system are positive and were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. Several models were used to correlate ternary behavior from the excess molar volume data of their constituent binaries and found to fit the data equally well. The best fit was based on a direct approach, without information on the component binary systems. [ABSTRACT FROM AUTHOR]

We studied the intermolecular interactions in ternary glycerol (Gly)-sample (S)-HO systems at 25 °C. By measuring the excess partial molar enthalpy of Gly, $H_{\mathrm{Gly}}^{\mathrm{E}}$, we evaluated the Gly-Gly enthalpic interaction, $H_{\mathrm{Gly}\mbox{--}\mathrm{Gly}}^{\mathrm{E}}$, in the presence of various samples (S). For S, tert-butanol (TBA), 1-propanol (1P), urea (UR), NaF, NaCl, NaBr, NaI, and NaSCN were used. It was found that hydrophobes (TBA and 1P) reduce the values of $H_{\mathrm{Gly}\mbox{--}\mathrm{Gly}}^{\mathrm{E}}$ considerably, but a hydrophile (UR) had very little effect on $H_{\mathrm{Gly}\mbox{--}\mathrm{Gly}}^{\mathrm{E}}$. The results with Na salts indicated that there have very little effect on $H_{\mathrm{Gly}\mbox{--}\mathrm{Gly}}^{\mathrm{E}}$. This contrasts with our earlier studies on 1P-S-HO in that Na, F and Cl are found as hydration centers from the induced changes on $H_{\mathrm{IP}\mbox{--}\mathrm{IP}}^{\mathrm{E}}$ in the presence of S, while Br, I, and SCN are found to act as hydrophiles. In comparison with the Hofmeister ranking of these ions, the kosmotropes are hydration centers and the more kosmotropic the higher the hydration number, consistent with the original Hofmeister's concept of 'HO withdrawing power.' Br, I and SCN, on the other hand, acted as hydrophiles and the more chaotropic they are the more hydrophilic. These observations hint that whatever effect each individual ion has on HO, it is sensitive only to hydrophobes (such as 1P) but not to hydrophiles (such as Gly). This may have an important bearing towards understanding the Hofmeister series, since biopolymers are amphiphilic and their surfaces are covered by hydrophobic as well as hydrophilic parts. [ABSTRACT FROM AUTHOR]

An association model is presented to describe vapor–liquid equilibria,liquid–liquid equilibria, and excess enthalpies of binary and ternary liquid solutionscontaining alcohols, aniline, and/or acetonitrile using the concepts of linearself-association of associated components and of solvation between unlike molecules.Calculated results also show that the model works well in representing thethermodynamic properties for alcohol + aniline, alcohol + acetonitrile, andalcohol + alcohol mixtures. [ABSTRACT FROM AUTHOR]

A modified form of the UNIQUAC model is presented to accurately reproducebinary phase equilibria and ternary and quaternary liquid-liquid equilibria ofaqueous and organic solutions. The model gives a good representation in thereproduction of binary coexistence curves over a wide temperature range usingtemperature-dependent parameters and of binary vapor-liquid equilibria usingtwo binary energy parameters, and in the correlation of ternary and quaternaryliquid-liquid equilibria using ternary and quaternary parameters, in addition tobinary parameters. The quaternary calculated results are compared with thoseobtained from the modified Wilson and extended UNIQUAC models. [ABSTRACT FROM AUTHOR]

Activity coefficients for sodium chloride in the NaCl + Na2SO4 + H2O ternary system were determined from emf measurements of the cell at 15, 25, 35, and 45°C and at total ionic strengths from 0.1 to 6 mol-kg−1. These activity coefficient were analyzed by using the Harned rule and the treatments of Scatchard–Rush–Johnson and Pitzer. The analysis of activity coefficients at “trace” concentration was also achieved and qualitatively interpreted by considering the ionic interactions that can take place in the mixed system. Finally, the excess Gibbs energy of the mixtures was calculated and qualitatively analyzed against the composition of the system. [ABSTRACT FROM AUTHOR]