Understanding the volume-solubility dependence: the mobile order and disorder view

Abstract

In the liquid phase, both the ephemeral character and the mobility of all intermolecular contacts and of H-bonds in particular have the result that, at constant pressure, the dissolution of a liquid or solid compound does not require the breaking of the solvent matrix. Contrary to the widely accepted idea, the observed volume-solubility relationships do not arise from the energy required to create cavities of the solute dimension in the solvents for locating the foreign molecules, but always have a hybrid origin stemming from the balance of elementary processes involved in the overall solubility phenomenon. In order to stress the quantitative solubility dependence of nonelectrolytes on their molar size, the solubility of aprotic substances in solvents of varying size, polarity and hydrogen bond ability was predicted from the mobile order and disorder (MOD) theory-derived solubility model. Obtained on a strictly thermodynamic basis, the model allows reliable estimates of solubility and provides a correct understanding of the solution behavior. The analysis of the relative importance of the various processes contributing to the overall solubility demonstrates that, in water for instance, the linear decrease in solubility versus increasing size of the solute is ruled by the balance of two volume-dependent entropic contributions: the hydrophobic effect opposing solution and the mixing entropy correction factor that favors solution.

Managing Phosphate Rock to Improve Nutrient Uptake, Phosphorus Use Efficiency, and Carrot Yields

“…This could be attributed to the addition of available P from the juice (as explained earlier) and increased availability of H + ions in citric acid, which might have caused the chelation of P binding cations in PR (Osman 2015). This result is in line with existing literature where, in liquid interphase at constant pressure, an increase in the volume of the dissolving solution increases intermolecular mobility and the contact of ephemeral molecules, which is particularly associated with the hydrogen bonds without the solvent matrix breakage (Ruelle 1999). Furthermore, an increase in dissolution volume increases the ion equilibrium effect, enhancing more solubilization of the ephemeral molecules before equilibrium is attained.…”

Surface properties of diluted solutions of cyclohexanol and cyclopentanol in ethylene glycol

“…The activity coefficients for the solute (γ 2 ) were obtained from mobile order-disorder theory (MOD) [22][23][24][25].…”

Dependence of the volume characteristics and viscosity of solutions of methanol-octane-naphthalene on composition at 25°C

“…To explain the effects of solubility, he proposed an approach based on the assumption that the formation of labile structures by cohesive forces with specific (hydrogen bonds) and nonspecific constituents [19]. The maximum solubility is thus associated with the contribution from nonspecific interactions; the mini mum solubility (in pure methanol) is determined by the entropy constituent of the free energy of solva tion [20]. It is interesting to note that even small addi tions of octane to the methanol led to a noticeable increase in naphthalene solubility, which can be explained by an increase in the negative contribution from entropy to the free energy of mixing, due to a rel ative increase in the volumes of the cavities in solu tion [19].…”

“…The reason for such a dependence could be change in the contribution to the entropy of mixing, due to the packing of molecules in a different geometry [20]. Another possible mechanism of the observed abnor malities could be associated with previously noted sta bilization of the structure of alcohols in the solvation shells of alkanes.…”