Stability constants for the formation of lead chloride complexes as a function of temperature and ionic strength.

The stability constants for the formation of lead (Pb2+) with chloride [Formula: see text] have been determined using a spectrophotometric method in NaClO4 solutions as a function of ionic strength (0-6 m) and temperature (15-45 °C). The results have been fitted to the equations: [Formula: see text] with standard errors of 0.05, 0.04 and 0.06, respectively. The thermodynamic values of log β1, logβ2 and logβ3 at 25.0 °C and the enthalpies of formation of PbCl+, PbCl20 and PbCl3- are in good agreement with literature values. We have combined our results with the earlier work of Seward (1984) to yield thermodynamic constants that are valid from 15 to 300 °C: [Formula: see text] with standard errors of 0.05, 0.08 and 0.10, respectively.