Solution Heat of Potassium Styphnate and Caesium Styphnate in Water and DMF at 298.15 K

Abstract

The dissolution and thermochemical properties of potassium styphnate [K2 (TNR) (H2O)] n and cesium styphnate [Cs2 (TNR)(H2O)2 ] n in water and N,N-dimethylformamide (DMF) at 298.15 K were studied by calorimetry.The processes are endothermic in water,and exothermic in DMF because of the different molecular structure and polarity of the solutes and solvents.Empirical formulas for the solution enthalpies (Δ sol H),relative apparent molar solution enthalpies (ФLi),relative partial molar enthalpies (Li),and dilution enthalpies (Δ dil H 1,2) are deduced by polynomial expressions,and standard solution enthalpies (Δ sol H m) are also calculated.