Isobaric vapour–liquid phase diagram and excess properties for the binary system 1,4-dioxane + water at 298.15 K, 318.15 K and 338.15 K

Isobaric vapour–liquid equilibrium (VLE) data have been measured for the binary system (1,4-dioxane + water) at atmospheric pressure. The compositions of the two phases in equilibrium were taken from the refractive indices curve of the system. The equilibrium data show a positive deviation from ideality and reveal an azeotrope. VLE data have been used to calculate the activity coefficients of the two components at 298.15 K, 318.15 K and 338.15 K. The excess properties have been deduced at these temperatures. Molar Gibbs free energy at liquid state was expressed as a function of composition and temperature. At the liquid state, excess entropies of the present system are negative over the entire composition range. Molecular-scale segregation in this system was proved.