A STRUCTURAL STUDY OF THE AQUA-ANIONS NO3-, BRO3- AND CLO3- BY DIFFERENCE-METHODS OF X-RAY-DIFFRACTION

The method of x-ray diffraction with isomorphic substitution has been extended to aqueous solutions containing complex ions. In a study of isomorphism between NO3-(aq), BrO3-(aq) and ClO3-(aq), it is found that the NO3- and BrO3- ions are isomorphic up to the level of the first-order difference indicating a similarity in their anion-hydration structure. Based on the isomorphism of these two ions, and because the water molecules are only weakly perturbed from their structure in pure water, a second-order difference calculation was made and the ion-ion pair correlation function of these two ions obtained. The results show that the most probable ion-ion separation is between 5 angstrom and 11 angstrom and the distance of closest approach is 4.8 angstrom. NO3- and BrO3- are found, however, not to be isomorphic with ClO3-.