Cation effects in molten nitrates. Their influence on the solubility product of silver bromide

Abstract

This paper reports a study of how a particular chemical equilibrium, namely the solution of silver bromide in molten potassium nitrate, is affected by the replacement of alkali-metal cations by alkaline-earth ones or by Li⁺.     Concentration cells with silver electrodes were employed to measure ΔG°, ΔH°, and ΔS° for the solution process and along with calculations made using Born-Haber cycles and the Sackur-Tetrode equation have provided values of ΔG°, ΔH°, and ΔS° for the solvation of AgBr in the various melts. AgBr is found to become increasingly insoluble as the proportion of divalent ion is increased. Some generalizations have been drawn from the tabulated results.     The solubility has also been studied in the hydrate melts Mg(NO₃)₂,6H₂O and Ca(NO₃)₂,4H₂O and the results compared to the anhydrous nitrate melts of the other cations of Group IIA.