Thermodynamics of molecular multicomponent solutions: Evaluation of the partial molar volume at infinite dilution

The present work deals with the evaluation of the partial molar volumes at infinite dilution (${\overline{v}}_i^{\infty }$) of n-components systems based on the dependence of the experimental density (ρ) on composition without involving binary systems. To do this, the multicomponent solution is interpreted by defining the component (1) as the solvent and the mixture of the remaining (n-1) components as the pseudocomponent (2n), characterized by the inner mole fraction $x_i^o$. After the analysis of the concept of infinite dilution, equations are derived that allow evaluating the partial molar volumes at infinite dilution of the pseudocomponent (${\overline{v}}_{2n}^{\infty }$), based on both the dependence of ln ρ $\left(x_{2n}\right)$ and the apparent molar volume ${\varphi }_{v_{2n}}\left(x_{2n}\right)$. Then, on the basis of experimental evidences about the linear variation of ${\overline{v}}_{2n}^{\infty }$ on $x_i^o$, the relationship between ${\overline{v}}_i^{\infty }$ and ${\overline{v}}_{2n}^{\infty }$ was established.

The applicability of the derived expressions was verified in 36 different cases corresponding to 11 ternary systems in the temperature range of 293.15 ≤ T/K ≤ 323.15.

Furthermore, the invariance of the partial molar volume at infinite dilution of the (n-1) components with the proportion in which they are mixed is verified.