SOME ALIPHATIC MONOCARBOXYLATE COMPLEXES OF BIVALENT METALS IN AQUEOUS SOLUTION. PART II. LEAD MONO- PROPIONATO AND MONO-FORMATO COMPLEXES

The composition of the complex formed between PI, and propionate ions has been found to be (PbProp.)+ from a study of the equilibrium hydrogen-ion concentrations in mixtures of evil-molecular lead nitrate and propionic acid solutions by "Job's method of continued variation'', using the increase of hydrogen-ion concentration as a new index. Proceeding similarly, the com­position of the complex formed between Pb2+ and formate ions has been found to be (PbFor)+. The thermodynamic dissociation constant, K, for the equilibrium \(PbProp.^+\rightleftharpoons Pb^{2+} + Prop.^-\) has been found oat as 4.57 x 10-3 at 28-30° by the direct application of "law of mass action", taking into account the activity coefficients of the individual ions, calculated from the ionic strength of the solution mixture of lead nitrate and propionic acid, employing the "Debyt-Huckel limiting law". Proceeding similarly, the thermodynamic dissociation constant K for the equilibrium \((PbFor)^+ \rightleftharpoons Pb^{2+} + For.^-\) has been found to be 182.0 x 10-3 at 26-30°. The first step of dissociation of lead formate in aqueous solution, viz. \(PbFor. \rightleftharpoons (PbFor.)^+ + For.^-\) For: has been suggested as nearly complete, and the reasons have been advanced