The enthalpies and heat capacities of hydration of ammonium and tetraalkylammonium bromides

The heat effects of solution of ammonium, tetraethylammonium, and tetrabutylammonium bromides in water were measured over the temperature range 277.15-328.15 K. The standard enthalpies of solution were calculated in the second approximation of the Debye-Hückel theory. The results were compared with the literature data on the enthalpies of solution of tetrabutylammonium and tetrapentylammonium bromides. The applicability of various equations suggested to describe the temperature dependences of enthalpy characteristics was analyzed. Heat capacity changes caused by the hydration of the salts and the temperature dependences of the entropies of hydration were calculated and discussed.