CHEMICAL AND ELECTROCHEMICAL-BEHAVIOR OF BICL3 IN A PBCL2 PLUS KCL EQUIMOLAR MIXTURE AT 475-DEGREES-C

The stability of bismuth chloride and oxide and the electrochemical re duction of Bi3+ ions in a PbCl2 + KCl equimolar mixture at 475-degrees -C were investigated using potentiometry, cyclic voltammetry, chronoam perometry and chronopotentiometry. The standard potential of the redox couple Bi(III)/Bi(0) and the solubility product of bismuth oxides wer e determined (E-degrees-Bi(s)/Bi(II) = - 0.92 +/- 0.01 V (vs. Cl2 (1 a tm)/Cl-), pK(s) = 4.9 +/- 0.1 (molality scale). A potential-oxoacidity diagram of bismuth is given. Bismuth (III) reduction involved a singl e three-electron transfer process at a tungsten electrode. The diffusi on coefficient of Bi(III), the thickness of the diffusion layer by the rmal convection and other kinetic parameters were also calculated.