Thermodynamics of mixtures with strongly negative deviations from Raoult'slaw Part 5. Excess molar volumes at 298.15 K for 1-alkanols plus dipropylamine systems: characterization in terms of the ERAS model

Excess molar volumes, V-m(E), at 298.15 K and atmospheric pressure over the entire composition range for binary mixtures of methanol, ethanol, 1-propa nol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol and 1-octanol with diprop ylamine are reported from densities measured with a vibrating-tube densimet er. All the excess volumes are large and negative over the whole mole fract ion range, indicating strong interactions between unlike molecules, which a re more important for the system involving methanol, characterized by the m ost negative V-m(E). For the remainder mixtures, V-m(E) at equimolar compos ition, is approximately constant. The V-m(E) curves are nearly symmetrical. V-m(E) and excess molar enthalpies, H-m(E), of the mixtures studied are con sistently described by the ERAS model. The ERAS parameters confirm that the strongest interactions between unlike molecules are encountered in the met hanol + dipropylamine system. (C) 2001 Elsevier Science B.V. All rights res erved.