Compressibility of Simple Fused Salts

Abstract

It is pointed out that the isothermal compressibility of monatomic molten salts should nearly equal that for a hypothetical fluid of uncharged ion cores at the same over‐all particle density as the salt. The validity of this relation is equivalent to verification of conjectures concerning the number‐average correlation function for ion pairs in the melt. When the ion core forces are treated as those acting between rigid spheres, it is readily possible to predict the distance of closest approach for an anion‐cation pair from experimentally determined compressibilities. The corresponding distances obtained in this manner for a series of molten halides are consistent with known ion sizes, and furthermore exhibit the proper homologous series trends.