EXCESS ENTHALPY SURFACES FOR N-HEPTANE PLUS CARBOXYLIC-ACID, AMYLAMINE AND N-OCTANOL MIXTURES BY THE NRTL MODEL

The temperature and composition dependences of the excess enthalpy, h( E), have been calculated using the NRTL model for mixtures of n-heptan e with the hydrogen-bonded liquids of acetic acid, propionic acid, amy lamine and n-octanol. Reduced and partial molar excess enthalpies were also calculated, The temperature-dependent parameters of the NRTL mod el, estimated directly from h(E) data for more than one isotherm, were used in the calculations. The overall deviations of all the experimen tal data points fall in the range 0.5-6.5% which shows highly satisfac tory correlation of h(E) data with the model. The temperature range fo r the mixtures is 285.15-330.15 K. The surfaces of excess enthalpy fun ctions facilitate better understanding of the thermodynamic properties of the hydrogen-bonded mixtures. The NRTL model is a reliable thermod ynamic model for studying the hydrogen-bonded mixtures in a qualitativ e and quantitative manner.