Effect of pressure on the dissociation of electrolytic solution : I. Electrical conductivity of hexammine cobalt(III) : chloride at high pressures

Abstract

From the equivalent conductivity, Λ, of dilute solution (1.0×10^-4～1.0×10^-3N) of [Co(NH_3)_6]Cl_3 at 25℃ under high pressure up to 600kg/cm^2, the degree of dissociation, α, and the dissociation constant, K, of [Co(NH_3)_6]Cl^2+ formed between [Co(NH_3)_6]^3+ and Cl^- have been determined. Λ increases with increasing pressure. α and K have the minimum values at about 400kg/cm^2 and the volume change, ΛV, caused by dissociation, are l7cm^3/mole at 300kg/cm^2 and -13cm^3/mole at 500kg/cm^2. The equivalent conductivity at infinite dilution, Λ_0 increases from 183.3 to 189.0 under pressure. This may be due to the increase of the ionic mobility which is related with the viscosity of water. The increase of Λ, therefore, may be mainly ascribed to the increase of ionic mobility under pressure.