The solubility products of some slightly soluble lead salts and the potentiometric titration of molybdate, tungstate, perrhenate and fluoride with use of a lead ion-selective electrode.
The conditional solubility products of lead molybdate, lead tungstate and lead perrhenate were found to be 1.2 +/- 0.3 x 10(-13), 8.4 +/- 0.1 x 10(-11) and 6.9 +/- 0.8 x 10(-9), respectively. In the case of lead perrhenate, the conditional stepwise formation constants for PbReO(+)(4) and Pb(ReO(4))(2) were found to be 1.2 +/- 0.1 x 10(5) and 1.2 +/- 0.2 x 10(3), respectively. Conditions for the potentiometric titration of molybdate, tungstate, perrhenate and fluoride with lead were established. The precipitates obtained during the titration of molybdate, perrhenate and fluoride mixtures have been proved to be physical mixtures of lead molybdate, perrhenate, fluoride and hydroxide, by infrared spectrometry. The pK(sp)-values of the lead salts of chromate, molybdate and tungstate are shown to increase linearly with increasing atomic number or electronegativity of the Group VI metal ion.
Chao
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EE
Department of Chemistry, University of Missouri-Kansas City, Kansas City, Missouri 64110, U.S.A.
Cheng
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KL