Concentration Effect of Sodium Chloride and Potassium Chloride on Enthalpies of Mixing of N-Glycylglycine with d-Mannitol in Aqueous Solutions at 298.15 K

The enthalpies of mixing of N-glycylglycine with d -mannitol in aqueous sodium chloride and potassium chloride solutions have been determined by using flow-mix isothermal microcalorimetry at 298.15 K. The results, along with the enthalpies of dilution of these solutes, have been analyzed using the McMillan−Mayer theory to obtain the heterotactic enthalpic interaction coefficients (h xy , h xxy , and h xyy ). It has been found that the heterotactic enthalpic pairwise interaction coefficients h xy between N -glycylglycine and d -mannitol in aqueous sodium chloride or potassium chloride solutions are negative and become less negative as the molality of sodium chloride or potassium chloride increases. The results have been interpreted from the point of view of solute−solute interactions and solvation effects.