X-ray diffraction study of MgCl₂ aqueous solutions

X-ray diffraction data for three aqueous solutions of MgCl₂ were analyzed. It is shown that in a very concentrated solution the structure and correlation functions can be reproduced almost completely by using a nearest-neighbor model of ionic hydration, whereas in the more dilute solutions a certain number of interactions between the hydrated cation and external water molecules must also be considered. The mean coordination geometry for the close hydration was found to be octahedral both for cation and anion with mean cation-water distances (2.10-2.12 Å) and mean anion-water distances (3.11-3.14 Å) in accordance with results found in other cases.