Caught in the Act of Dissolution

Abstract

The ionic dissociation of acids such as HCl and HBr in water is driven by a substantial energy release when the ions are formed in an extended medium. But how many water molecules does it take to trigger this dissociation? In their Perspective, Robertson and Johnson highlight the report by Hurley et al., who have answered this question for the case of HBr. Their experiments on small water clusters indicate that just five water molecules are enough to ionize HBr.