Use of Pitzer\u27s Equations to Determine the Media Effect on the Formation of Lead Chloro Complexes

The spectrophotometric measurements of chloro complexes of lead in aqueous HCl, NaCl, MgCl2 and CaCl2 solutions at 25°C have been analyzed using Pitzer\u27s specific interaction equations. Parameters for activity coefficients of the complexes PbCl+, PbCl20 and PbCl3− have been determined for the various media. Values of K1= 30.0 ± 0.6 \u3eK1= 30.0 ± 0.6 , K2= 106.7 ± 2.1 \u3eK2= 106.7 ± 2.1 and K3= 73.0 ± 1.5 \u3eK3= 73.0 ± 1.5 were obtained for the cumulative formation constants. [Pb2++ nCl−→ PbCln2−n) \u3ePb2++ nCl−→ PbCln2−n) ]. These values are in reasonable agreement with literature data. The Pitzer parameters for the PbCl ion pairs in various media were used to calculate the speciation of Pb2+ in an artificial seawater solution