The solubility product of AgI and the complexes of AgI and iodide ions in water‐acetone mixtures

Abstract

AbstractThe solubility product L of AgI in water‐acetone mixtures was determined from e.m.f. measurement in concentration elements. The diffusion potential was eliminated by Owen's method. As the solubility product was measured in three electrolyte concentrations the solubility product in infinite dilution could be found by extrapolation.The complex formation of AgI2− increases with increasing acetone concentration. The equilibrium constant K = \documentclass{article}\pagestyle{empty}\begin{document}${\rm K}=\frac{{{\rm a}_{{\rm I}^-}}}{{{\rm a}_{{\rm AgI}_{\rm 2}^-}}}$\end{document} was also determined by e.m.f. measurements. ‐RT ln K proves to be a linear function of the acetone concentration in mole %.The formation of higher complexes (AgnIn+m)m− is analysed. The complex Ag4I6= is the simplest complex that would confirm the experiment. A further proof has been found in the molecular weight determination in the ultracentrifuge.The standard free energy of solution of AgI, ‐RT ln L, is a nearly quadratic function of the acetone concentration in mole %. At low concentrations of acetone (up to 50 vol. %) the influence on L is low, but at higher concentrations the solubility decreases rapidly.The measurements were performed at 25.00 ± 0.02° C.