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The binding mean spherical approximation theory is used to describe the thermodynamic properties of dicarboxylic acid salts by adding a chain term in the free energy. The dianions in these solutions are modeled as flexible charged chains composed of two, three, or four spheres. Five aqueous solutions of such salts are studied in different concentration ranges: dipotassium oxalate, disodium malonate, disodium succinate, potassium tartrate, and sodium tartrate. A description of the experimental deviations from ideality (osmotic and activity coefficients) for these salts is obtained. The model is compared with a previous one that does not include a chain contribution. It is found that the model with a chain contribution provides a more physically sound framework. [ABSTRACT FROM AUTHOR]

In this work, the binding mean spherical approximation (BiMSA) theory is used to describe osmotic and activities coefficients for electrolytes solutions up to high temperatures. Four salts are analysed: NaCl, LiCl, $ {\rm MgCl}_2 $ MgCl 2 and $ {\rm CaCl}_2 $ CaCl 2 , in the temperature range of 25 $ ^{\circ } $ ∘ C to 300 $ ^{\circ } $ ∘ C and molalities from 0.05 to 6 molal. A good representation of experimental data is obtained for all salts and temperatures considered by introducing temperature-dependent cation size and permittivity in a suitable way. The proportion of ion pairs (that are formed at sufficiently high temperature in these solutions) for each salt is predicted from the theory, showing a pronounced increase for temperatures above 100 $ ^{\circ } $ ∘ C. A good agreement is found between the values of optimised and experimental association constants given in the literature. [ABSTRACT FROM AUTHOR]

In this work the thermodynamic geometry (TG) of semiclassical fluids is analyzed. We present results for two models. The first one is a semiclassical hard-sphere (SCHS) fluid whose Helmholtz free energy is obtained from path-integral Monte Carlo simulations. It is found that, due to quantum contributions in the thermodynamic potential, the anomaly found in TG for the classical hard-sphere fluid related to the sign of the scalar curvature is now avoided in a considerable region of the thermodynamic space. The second model is a semiclassical square-well fluid, described by a SCHS repulsive interaction coupled with a classical attractive square-well contribution. The behavior of the semiclassical curvature scalar as a function of the thermal de Broglie wavelength λ_{B} is analyzed for several attractive-potential ranges. A description of the semiclassical R Widom lines, defined by the maxima of the curvature scalar, is also obtained and results are compared with the corresponding classical systems for different square-well ranges.