X-ray diffraction study of anion hydration in solutions of potassium halides

Anion hydration in aqueous solutions of 1 : I electrolytes KHal (Hal = F, C l, Br, I) was studied at 298.15 K; the water-to-electrolyte molar ratio in the KHal-H2O systems was 1 : 15. The experimental electron-density radial d istribution functions for atoms reflect changes in the structure of solutio ns associated with anion hydration. An increase in the radius of the anion is accompanied by switching from the formation of contact ion pairs to the independent hydration of the cation and anion. The possible variants of the geometry of the nearest surroundings of the counterions are considered.