Thermodynamic properties of some binary mixtures of specifically interacting non-electrolytes. Part 1.—Aniline + toluene
Abstract
Heats of mixing hM of aniline + toluene have been measured at 30 and 50°C over the entire composition range and have been correlated with published values of the excess free energy gE to obtain the excess functions of the system between 30 and 100°C. The results have been interpreted assuming aniline to be associated. The excess functions calculated by means of the Mecke-Kempter model, characterized by only two adjustable parameters, agree excellently with the experimental gE, very satisfactorily with hM, and predict correctly the almost zero excess heat capacity cEp of the mixture. The association constant K, the enthalpy of association ΔH°(energy of the N—H … N bond), and the entropy of association ΔS° have been derived. K is given by the equation log K= 442/T–1.06, from which ΔH°=–2025 ± 50 cal/mole (in agreement with spectroscopic and other data), and ΔS°=–4.85 ± 0.20 cal/deg mole.