Structural changes of water caused by non-electrolytes: Volumetric and compressibility approach for urea-like analogues
Hydration of thiourea (TU), hydroxyurea (HU, hydroxycarbamide), acetone (AC, 2-propanone) and dimethyl sulfoxide (DMSO) has been investigated with the help of the volumetric and compression measurement. The apparent molar volumes and the apparent molar isentropic (adiabatic) compression have been calculated from the density and speed of sound data at temperatures ranging from 288.15 to 308.15 K at atmospheric pressure (0.1 MPa). From these data the standard partial molar volumes and the standard partial molar isentropic compressions have been calculated. The properties of the hydration spheres formed around investigated solutes have been characterised based on four parameters: (i) empirical slope for the dependency of the apparent molar volume on the concentration, (ii) difference between standard partial molar volume and van der Waals volume, (iii) standard partial molar compression, (iv) temperature dependency of the standard partial molar compression. The obtained results have been discussed and compared with the solvation properties of the N-alkyl derivatives of urea.
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