Excess Enthalpy and Heat Capacity for an Ethanol-Water Mixture
Consider a binary mixture of ethanol and water. Expressions for the excess enthalpy (in J/mol) and heat capacity (in J/mol·K) have been determined for this binary liquid system for the temperature range 298.15 K to 383.15 K by fitting experimental data to an empirical equation .
This equation for the excess enthalpy is , where is the temperature and is the ethanol mole fraction. The excess heat capacity is given by . Finally, , where and , , and are appropriate constants tabulated in .
This Demonstration plots both excess properties versus ethanol mole fraction for user-selected values of temperature.
 J. A. Larkin, "Thermodynamic Properties of Aqueous Non-Electrolyte Mixtures I. Excess Enthalpy for Water + Ethanol at 298.15 to 383.15 K," Journal of Chemical Thermodynamics, 7(2), 1975 pp. 137–148. doi:10.1016/0021-9614(75)90261-X.