Peculiar points in the phase diagram of the water-alcohol solutions

Abstract

The work is devoted to the investigation of nontrivial behavior of dilute water-alcohol solutions. The temperature and concentration dependencies of the contraction for aqueous solutions of ethanol and methanol are analyzed. The existence of a specific point, the so-called peculiar point, was established. It is shown that wateralcohol solutions of different types obey the principle of corresponding states if temperature and volume fraction are used as principal coordinates. In this case, the concentration of the peculiar point for different solutions is close to x ν = 0.28. Several predictions are made.

Refractometry of Water–Ethanol Solutions near Their Contraction Point

“…For instance, in order to reproduce the experimental values for water refractive index, we have to put 1 2 (2) ( ) ∼ ∼ 1 70 (1) . Then, at = 4, we obtain the estimate (2) ( )/ (1) ≈ 0.01, which practically coincides with estimate (7) (it is accepted that…”

“…The analysis of the behavior of the contraction and the molecular light scattering in dilute aqueous alcohol solutions [1][2][3][4] showed that, in the interval 0.05 < < < 0.1 of the alcohol mole fraction , there emerges a region of special thermodynamic states. In this region, the curves describing the concentration dependences of the contraction at various temperatures intersect at the single, so-called special, point.…”

“…MALOMUZH, M.V. STIRANETS, 2015 [2,4]. Namely, it was shown that the special point of the solution can be associated with the arrangement of water molecules around alcohol ones in the form of monomolecular layers.…”

Determination of characteristics of anomalous light scattering in the gradient solutions using electronic speckle-pattern interferometry control of concentration distribution

“…This has been demonstrated by measuring the characteristic times of collective motions of micro-inhomogeneities with a correlation spectroscopy technique [7][8][9]. Consequently, one cannot ensure that the concentration at each point of the solution can be found when basing only on the calculations of the mutual diffusion.…”

Anomalous Light Scattering in Aqueous KCl Solutions

“…In the vicinity of those points, the integral intensity of MLS increases by an order of magnitude [1][2][3], and the halfwidth of MLS spectra is several orders of magnitude narrower than the half-width of the spectra corresponding to the concentration light scattering [4]. In a cycle of works [5][6][7][8][9][10][11], we showed that the singular points of this kind almost exactly coincide with the points, at which the concentration curves of solution contraction measured at various temperatures intersect. This fact means that the physical nature of those points is identical or, more precisely, it is associated with the solution contraction (compaction), i.e.…”