IONIC SELF-DIFFUSION COEFFICIENTS OF GD-153(III) IN GD(NO3)(3) SOLUTIONS IN WATER-DIOXAN MIXTURES AT 25-DEGREES-C

The measurement of ionic self-diffusion coefficients of the lanthanide ions Gd-153(III) in asymmetrical electrolytes (3:1) solutions of Gd(N O3)(3) in hydro-organic water-dioxan mixtures (at a low dielectric con stant) gives evidence of the progressive association of ion pairs. The study of different physical-chemical properties in all the domains of composition shows the existence of three regions with distinct behavi ours. The application of association theory to such an asymmetrical el ectrolyte (3:1) with a polyvalent cation enables us to delimit the val idity of the Bjerrum and Fuoss theories.