Enthalpies of solution and crystallization ofL-ascorbic acid in aqueous solution

Abstract

Enthalpies of solution for (L-ascorbic acid+water) have been measured in a SETARAM C80 D mixing calorimeter over the composition range of homogeneous solutions at temperatures of 298.15 K and 323.15 K. The results are reported in terms of excess molar enthalpies for {(xC6H8O6+(1−x)H2O} and molar enthalpies of solution for C6H8O6. The temperature and concentration dependence of the enthalpies of solution are given by a Redlich–Kister equation fitted with the experimental data. Enthalpies of crystallization ofL-ascorbic acid in aqueous solutions have been measured at the temperatures (293.15, 298.15, and 303.15) K during unseeded programmed crystallization. The molar enthalpies of crystallization for C6H8O6obtained experimentally agree well with those calculated from partial molar enthalpies of solution data of C6H8O6.