Intradiffusion coefficients for zinc and water and shear viscosities in aqueous zinc(II) perchlorate solutions at 25°C
Intradiffusion coefficients for 36C have been measured in solutions of zinc perchlorate of concentration 0.1 to 3 mol dm–3 at 25C by the diaphragm cell technique. In addition, intradiffusion coefficients for perchlorate ions in zinc chloride solutions have been measured over a concentration range at 25C. The results confirm previous work on the effect of complexation on diffusion in zinc chloride solutions above a salt concentration of 0.1M. The present data, together with literature data for diffusion coefficients of the other species present in the zinc perchlorate electrolyte system, have enabled a simple analysis of the hydration around the zinc ions to be carried out. This indicates that the water diffusion data are consistent with the zinc ions having an effective hydration sphere of 11 (2) water molecules. This is in keeping with values obtained for other simple divalent electrolytes using the same model. The model is extended here to allow analysis of water diffusion in zinc chloride solutions taking into account the presence of complexed chloro-zinc species. The experimental data are consistent with the effective hydration of the chloro-zinc complexes being independent of the number of chloride ligands and equal to 183 over a concentration range of 0 tol mol-dm–3. This postulate is discussed in terms of its consequences on the water ligand dynamics for the complex equilibria.