| Popis: |
The solubility of divalent lead chloride is measured at 25°C in aqueous solutions {H2O + HClO4 + HCl} and {H2O + HClO4 + Pb(ClO4)2} as a function of the initial ionic strength X (0 ⩽ X ⩽ 1 mol kg−1). The apparent solubility product of lead chloride, Ks, and the apparent constants βi of the equilibria (i) have been determined at different values of the equilibrium ionic strength, I Pb2+(aq) + i Cl−(aq) = PbCl(i−2)−i(aq) (i) The experimental values are well interpreted by the existence of Pb2+, PbCl+, PbCl2 and PbCl−3. The results permitted an empirical representation of Ks and βi values as functions of I which may be extrapolated to infinite dilution. The thermodynamic solubility product and the thermodynamic constants of the equilibria (i) were determined at 25°C K0s = (1.696±0.004)×10−5 K01 = 40.3±0.2 K02 = 47.2±3 K03 = 420±10 From these values, we have calculated the standard Gibbs energy function of formation of the different lead complexes at 25°C ΔfG0(PbCl+) = −164820 J mol−1 ΔfG0(PbCl2) = −296440 J mol−1 ΔfG0(PbCl−3) = −433084 J mol−1 |
