POTENTIOMETRIC AND CALORIMETRIC STUDY OF THE SYSTEM AG+-NH3 IN 3 M NACLO4, 3 M LICLO4 AND 3 M NANO3 MEDIA

The equilibrium constants and the enthalpy changes for the reactions NH4 + = NH3 + H+ Ag+ + NH3 = AgNH3 + Ag+ + 2NH3 = Ag(NH3)2 + have been determined by e.m.f. and calorimetric measurements at 25°C in 3 M NaClO4, 3 M LiClO4 and 3 M NaNO3 media. The results are summarized in Tables 1, 3 and 7. The dissociation constants of NH4 + were almost the same in the three different media. We found little difference in values of formation constants of silver-ammine complexes between 3 M NaClO4 and 3 M LiClO4, while in 3 M NaNO3 they were considerably lower than in the perchlorate media. This difference was mainly ascribed to the formation of AgNO3 species in the nitrate medium. As to the enthalpy changes for the formation of AgNH3 + and Ag(NH3)2 + there was found little difference between the values in the three media. © 1979.