Calculated X-ray scattering functions for models for aqueous Ph4AsCl which fit the osmotic coefficient data

Models for Ph₄AsCl (aq.) which incorporate a Gurney cosphere overlap term are fitted to the published osmotic coefficient data. Models with predominantly + – and those with predominantly ++ ion pairing are about equally successful. Further calculations are then made to see how difficult it might be to distinguish between the models by scattering x rays, electrons, or neutrons from the aqueous solution in the rather low concentration range in which the models might be realistic. The x-ray experiment is promising, but high precision in the small-angle region would be necessary.