Formation equilibria of silver amminocomplexes at temperatures up to 453 K

Abstract

The formation equilibria of silver amminocomplexes were investigated by potentiometric method over the temperature range 333 to 453 K. On the grounds of emf measurements of a concentration cell consisting of[Formula: see text]the equilibrium concentrations of uncomplexed silver ions [Ag+] were determined in a Ag—NH3—H2O system. The Leden method was followed and the mean number of ligands [Formula: see text] per silver atom bound in amminocomplexes as well as the equilibrium concentration of free ammonia [NH3] were calculated. From the values obtained above the stability constants of silver amminocomplexes β1 and β2 were determined over the temperature range 333 to 453 K. The dependence of log β1 versus temperature was described by the equation: log β1 = 6.89 − 1.16 × 10−2 T whereas for log β2 the linear equation: log β2 = 14.10 − 2.41 × 10−2 T is satisfied only up to 413 K. Above 413 K the nature of the dependence is changed.