Activity coefficients of single complexes and coordination equilibria in three-component systems of the type MX2+ solvent + diluent. Systems involving MnCl2, NiCl2, pyridine, benzene, chlorobenzene and o-dichlorobenzene

Abstract

Solubility isotherms for MnCl₂ and NiCl₂ in mixtures of pyridine with benzene and with o-dichlorobenzene have been determined at 20 and 30°C, and those of MnCl₂ in mixtures of pyridine with chlorobenzene supplemented with results relating to the metastable equilibria involving the MnCl₂(py)₂ and MnCl₂(py)₄ solid phases. The solvent-dependent activity coefficients of the pseudooctahedral solution complexes [NiCl₂(py)₄] and [MnCl₂(py)₄] have been calculated from solubility data and are found to be the same, within experimental error, at any given composition of the mixed solvent. Taking this into account, the activities of pyridine in the liquid mixtures have been calculated from the solubility data and they agree well with the results obtained by the vapour pressure method.