Physico-chemical studies in non-aqueous solvents. Part XII. Thermochemical studies of some 1:1 electrolytes in N,N-dimethylacetamide

Abstract

Heats of solution of alkali metal, silver, ammonium and substituted ammonium perchlorates, lithium chloride and potassium thiocyanate have been measured in the concentration range 1.26-112.8×10⁻³ mol l⁻¹ in N,N-dimethylacetamide (DMA) at 26.9°C. Slopes of the linear plots of heat of solution vs. square root of concentration are two to three times higher than the Debye-Huckel limiting slope indicating thereby complete dissociation of the electrolytes. Standard heats of solution of the electrolytes in DMA are higher than those in formamide and N-methylformamide and are comparable to those in N,N-dimethylformamide. Buckingham's model has been used to determine the solvation enthalpies of various ions in this solvent. The results indicate that ion solvation enthalpies decrease with increase in size of the ions and that the anion solvation enthalpies are higher than cation solvation enthalpies which is consistent with the findings in various solvents.