Enthalpies of solution and crystallization of fumaric acid in aqueous solution

Enthalpies of solution for (fumaric acid + water) have been measured at the temperatures (298.15, 313.15, and 333.15) K over the composition range of homogeneous solutions by using a SETARAM C80 D mixing calorimeter. The conc entration and temperature dependence of the molar enthalpies of solutions a nd excess molar enthalpies are given by a Redlich-Kister equation fitted to the experimental data. The standard enthalpy of solution was determined by considering the effect of incomplete dissociation of C4H4O4 on the solutio n data. Enthalpies of crystallization of fumaric acid in aqueous solutions have been measured at the temperatures (298.15, 303.15, 308.15, and 313.15) K during unseeded programmed crystallization. The molar enthalpies of crys tallization data are thermodynamically consistent with those calculated fro m partial molar enthalpies of solution. (C) 2000 Academic Press.