An investigation of the lead(II)-hydroxide system.
A detailed investigation of the Pb(II)/OH(-) system has been made in NaClO(4) media at 25 degrees C. Combined UV-vis spectrophotometric-potentiometric titrations at [Pb(II)](T) < or = 10 microM using a long path length cell detected only four mononuclear hydroxide complexes. The values of log beta(1)(q)(), for the equilibria Pb(2+)(aq) + qH(2)O <--> Pb(OH)(q)()((2)(-)(q)()()+)(aq) + qH(+)(aq), were -7.2, -16.1, -26.5, and -38.0 for q = 1-4, respectively, at ionic strength I = 1 M (NaClO(4)). Similar results were obtained at I = 5 M (NaClO(4)). No evidence was found for higher order complexes (q > 4) even at very high [OH(-)]/[Pb(II)] ratios, nor for polynuclear species at [Pb(II)](T) < or = 10 microM. Measurements using (207)Pb-NMR and Raman spectroscopies and differential pulse polarography (DPP) provided only semiquantitative confirmation. The mononuclear Pb(OH)(q)()((2)(-)(q)()()+)(aq) complexes are the only hydrolyzed species likely to be significant under typical environmental and biological conditions.
Perera
W N
WN
Chemistry Department, Murdoch University, Murdoch, Western Australia 6150, Australia.
Hefter
G
G
Sipos
P M
PM
D006878:Hydroxides / Q000737:chemistry*; D017736:Ion-Selective Electrodes; D007854:Lead / Q000032:analysis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D010472:Perchlorates / Q000737:chemistry; D011048:Polarography; D017670:Sodium Compounds / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D013059:Spectrum Analysis, Raman; D013237:Stereoisomerism
D006878:Hydroxides; D010472:Perchlorates; D017670:Sodium Compounds; C432863:lead hydroxide; D007854:Lead; C031068:sodium perchlorate