Thermodynamics of Ion Pairing in Lead Nitrate Solutions As Determined with ²⁰⁷Pb NMR Spectroscopy

Abstract

The temperature and concentration variations in 207 Pb NMR shifts of Pb(NO 3 ) 2 in aqueous solutions are analyzed in terms of exchange between aquated lead ion and the Pb(NO 3 ) + ion complex according to the reaction PbNO 3 + (aq) = Pb 2+ (aq) + NO 3 - (aq). The analysis gives an enthalpy of dissociation of −3.0 ± 0.2 kcal mol -1 and an entropy of dissociation of −11.9 ± 0.4 cal K -1 mol -1 .