A COMPREHENSIVE THERMODYNAMIC INVESTIGATION OF WATER ETHANOLAMINE MIXTURES AT 10-DEGREES-C, 25-DEGREES-C, AND 40-DEGREES-C

The density, isobaric specific heat capacity, and isentropic compressi bility of water-ethanolamine (W-EA) mixtures have been measured at thr ee temperatures (10, 25, and 40-degrees-C) over the entire composition range. The results were used to calculate various thermodynamic exces s functions of these mixtures, namely: the excess molar volume (V(m)E) , excess molar isentropic and isothermal compressibilities (kappa(S,m) E, kappa(T,m)E), excess molar isobaric and isochoric heat capacities ( C(p,m)E, C(V,m)E), and excess molar isobaric expansion (partial deriva tive V(m)E/partial derivative T)p. The corresponding partial molar qua ntities for ethanolamine in the mixtures were also computed. These exc ess and partial molar quantities were compared with those observed ear lier in the water - ethylene glycol (W-EG) (1) and in the water-2-meth oxyethanol (W-ME) (2) mixtures. The similarities and differences in th e properties of these systems are interpreted on the basis of the spec ific molecular features of the cosolvents and the concepts of cooperat ive fluctuations and hydrogen-bonding connectivity in liquid water and dilute aqueous solutions.