The volume characteristics of solution of naphthalene in heptane-ethanol mixtures at 298.15 K

The solubility of naphthalene was studied by the isothermal saturation method, and the density of naphthalene-heptane-ethanol solutions at 298.15 K was measured using an oscillating tube densimeter. The results were used to calculate the volume characteristics of naphthalene in the systems specified. The solubility of naphthalene in heptane was substantially higher than in ethanol. The composition dependences of apparent partial molar volumes contained extrema. The reason for such nonlinear dependences can be a sharp change in the contribution to the entropy of mixing related to the packing of molecules of different diameters (naphthalene and heptane). Another possible mechanism of these anomalies can be related to the stabilization of the structure of alkanols in the solvation sheath of alkanes noticed earlier.