On the acidity of hydrogen fluoride

An explanation is proposed for the rapid increase in acidity in progressing from dilute solutions of HF in H₂O to solutions of greater concentration ($\text{ca.}$ 10M). Anhydrous HF has been shown to be more acidic than generally believed and to require very small adventitious concentrations of F^? to become quite basic. Oxidation of I₂ is used to demonstrate the dependence of the nature of species in HF solution on the acidity or basicity of the medium.