Excess enthalpy surfaces for n-heptane + 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-heptane with the hydrogen-bonded liquids of acetic acid, propionic acid, amylamine and n-octanol. Reduced and partial molar excess enthalpies were also calculated. The temperature-dependent parameters of the nrtl model, estimated directly from h^E data for more than one isotherm, were used in the calculations. The overall deviations of all the experimental data points fall in the range 0.5-6.5% which shows highly satisfactory correlation of h^E data with the model. The temperature range for the mixtures is 285.15-330.15 K. The surfaces of excess enthalpy functions facilitate better understanding of the thermodynamic properties of the hydrogen-bonded mixtures. The nrtl model is a reliable thermodynamic model for studying the hydrogen-bonded mixtures in a qualitative and quantitative manner.