Compressibility Studies of Binary Solutions Involving Water as a Solute in Nonaqueous Solvents at T = 298.15 K

Abstract

The experimental measurements of the speed of sound and density in binary solutions of MeOH, EtOH, n-PrOH, n-BuOH, acetonitrile (ACN), dimethylformamide (DMF), tetrahydrofuran (THF), and 1,4-dioxane as solvents and water as the solute in the concentration range of 0.02 mol·kg-1 to 1 mol·kg-1 at T = 298.15 K are reported. The data are used to obtain the isentropic compressibility of solution. The apparent molar volume (φV) and compressibility (φK) of water at different concentrations are evaluated. The data of limiting volume ( ) and compressibility ( ) and their concentration variation are examined to study the effect due to water−solvent and water−water interactions. It has been observed that there is loss of volume and compressibility of liquid water molecules in transferring them from the pure liquid state to a nonaqueous solvent. An attempt is made to explain the large negative value of in alcohols due to H-bonding characteristics of water and alcohol and the effect of the presence of nonpolar groups. The possibilities of the presence of water-centered complexes or participation of water in a chain-like structure along with pressure effects are examined on the basis of concentration variation of the derived properties.

Volumetric and compressibility properties of liquid water as a solute in glycolic, propylene carbonate, and tetramethylurea solutions at T=298.15K

“…Introduction of a non-polar groups elevates this effect as can be seen in case of PG and TMU, where, there is comparatively more volume loss. Similar comparison with other solvents like DMF, dioxane, THF and acetonitrile (15.1 AE 10 À6 , 17.3 AE 10 À6 , 17.1 AE 10 À6 , and 17.4 AE 10 À6 m 3 AE mol À1 , respectively) [8] indicate the individuality of the solvent structures and the nature of dipolar forces as well as ability to have H-bonding interactions. In case of PC, we observed increase in the molar volume of water which may be attributed to specific H-bonding interaction with the etheric oxygen of the solvent molecules.…”

“…and water as a solute in the concentration range of 0.1-1 mol AE kg À1 of water at T = 298.15 K [8,9] for solutions having enough solubility or up to the saturation if solubility is limited. Our dielectric studies revealed that water dissolves in benzene may be in cyclic trimer form exhibiting trimer-monomer type of dissociative equilibria [9].…”

“…Our dielectric studies revealed that water dissolves in benzene may be in cyclic trimer form exhibiting trimer-monomer type of dissociative equilibria [9]. We also examined possibilities of the presence of water-centered complexes or participation of water in the chain like solvent structure (alcohols) and in apolar solvents like THF, dioxane, acetonitrile and DMF on the basis of volumetric and compressibility studies [8]. We observed that in aqueous methanolic and aqueous ethanolic solutions water exhibits differences in excess volumes and compressibilities as compared to other apolar solvents because of the presence of H-bonded linear structures of the solvents themselves.…”

Water as a solute in nitromethane: Effect of H2O–D2O isotope substitution on the solution volumetric properties between 278.15K and 318.15K

“…Water dissolved in the aprotic dipolar solvent present a rare opportunity for studying both the state and specific features of solute molecules being hydrogen-non-bonded in the three-dimensional network characteristic of the ''pure" aqueous component and the nature of their effect on the structure and thermodynamic properties of the surrounding (solvating) medium [1][2][3][4][5][6][7]. Here, the point is that the aprotic dipolar solvent is such a dissolving medium, whose structural packing contains molecules that do not form strong hydrogen bonds (due to the absence of proton-donating centers) but allows sufficiently strong specific interactions (via H-bonding) with molecules of an electron-accepting protic solute, which in this case is water [3].…”

“…At the same time, although thermodynamics does not yield directly the structural aspects of the intermolecular interaction, one can derive meaningful inferences from thermodynamic properties such as partial volume and enthalpy function as well as their derivatives (partial expansibility, compressibility and heat capacity) indirectly [2][3][4]7,8]. From this viewpoint, approaches that cause ''minimal perturbation" of a solution structure seem to be most informative for the specified thermodynamic studies.…”