New approach to the analysis of the enthalpy of ternary systems. Solutions of salts in water-amide mixtures

An approach was proposed based on the representation of the enthalpy of a ternary system comprising a binary solvent and a solute as the sum of contributions from the solute interaction with mixture components. The enthalpy parameters of interaction were determined. The correlation of these parameters with the enthalpy coefficients of pair interactions in the McMillan-Mayer theory and with the enthalpies of solution in the components of a binary mixture was shown. The heats of solution of inorganic and organic salts in water mixtures with formamide (FA), N-methylformamide (MFA), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), and hexamethylphosphoric triamide (HMPT) (altogether 15 systems) were analyzed.