Potentiometric Titration of Lead(II) by Iodide in Acetone and Formation of Complex PbI3 –

Abstract

Potentiometric and differential potentiometric titrations of Pb²⁺ by iodide in acetone using different indicator electrodes: Pb, Cu and Pt were studied. Two end-points were observed, the first one according to the following equation: Pb²⁺ + 2I^– → PbI₂↓. While, the second end-point according to the following equation: PbI₂↓ + I^– → PbI₃ ^–. The following complex PbI₃ ^– is formed in acetone solution, for the first time, a clearly and consistently log K = -21.92 (dissociation constant) is obtained. Solubility product (SP) of the deposit (PbI₂↓) is calculated, the values of log SP_PbI2↓ were between -18.30 to -18.80. A 103.5 μg of Pb²⁺ was determined with relative standard deviation not to exceed ± 3.1 %.