X-ray and neutron diffraction studies on concentrated aqueous solutions of sodium nitrate and silver nitrate

Abstract

Neutron diffraction experiments have been conducted on 3.1 M (molar) solutions of 107AgNO3 and 109AgNO3 in heavy water, and the first-order difference method of isotopic substitution has been used to obtain the local structure around Ag(aq)+. The results of this work have been used in conjunction with those from an X-ray diffraction study of 3.1 M (molar) AgNO3 and NaNO3, to establish the degree of structural isomorphism between Na(aq)+ and Ag(aq)+. It has been shown that Na(aq)+ and Ag(aq)+ are sufficiently isomorphic to enable useful pictures to be obtained for both Na+ hydration and Ag+-Ag+ coordination. Comparison with previous results for the other alkali metal ions shows that, in terms of the strength of hydration, Na+ is intermediate between Li+ and K+.