Enthalpic Interaction Coefficients of Formamide in Aqueous Methanol and Ethanol Solutions at 298.15 K

The dilution enthalpies of formamide in aqueous methanol and ethanol solutions have been determined using a CSC-4400 isothermal calorimeter at 298.15 K. The homogeneous solution enthalpic interaction coefficients have been calculated over a range of alcohol concentrations according to the excess enthalpy concept. The results show that the enthalpic pair interaction coefficients h ₂ of formamide are negative in aqueous alcohol solutions and pass through a minimum in mixed solvents, whereas the h ₂ coefficients of formamide in aqueous ethanol solutions are more negative than those in aqueous methanol solutions. The results are discussed in terms of solute-solute and solute-solvent interactions.