Thermodynamics of Dilution of N,N-Dimethylformamide in Aqueous Sodium Chloride Solutions at Different Concentrations

The dilution enthalpies of N,N-dimethylformamide (DMF) in pure water and aqueous sodium chloride solutions were determined by using flow microcalorimetry at 298.15 K. The homogeneous enthalpic interaction coefficients in the range of sodium chloride concentration from 0 to 0.6 mol·kg-1 were calculated according to the McMillan-Mayer theory. It was found that enthalpic pairwise interaction coefficients (h2) of DMF were all positive in aqueous sodium chloride solutions and became larger with increasing the concentration of sodium chloride. The results were discussed in terms of the solute-solute and solute-solvent interactions.