Excess enthalpies for ternary aqueous solutions of glycerol and urea at 25°C

A strategy is described to determine the second and third cross interaction coefficients hij, hiij, and hijj for the viral expansion of the excess enthalpies of aqueous solutions of non-electrolytes when these coefficients are comparable in magnitude and opposite in sign. Gross errors can occur especially if both self interaction coefficients hii and hjj are small, if the heats of mixing are small, or if the extrapolation must be carried out from moderately concentrated regions. The exemplary case of two solutes, as different as glycerol and urea, is extensively discussed. © 1983 Plenum Publishing Corporation.