Influence of alcohols on Ca2+ hydration

Self-diffusion coefficients of Ca2+ and Cl− were measured at 298 K in aqueous solutions of methanol, n-propanol and tert-butanol. An influence of alcohol concentration on Ca2+ and Cl− radii was investigated. Ca2+ radius in aqueous solution coincides with the size of the first coordination shell. Cl− radius is smaller than the size of the first coordination shell. Alcohols destabilize the hydration shell of Cl− and its radius is like that in crystal. Hydration of Ca2+ depends on the solvent structure. Small amounts of methanol and tert-butanol, but not of n-propanol, destroy slightly the first shell of Ca2+, whereas in 'mixed state region' of n-propanol and tert-butanol aqueous solutions the shells of Ca2+ are like those in water, because cations are embedded in water domains.