Salzkryoskopie II. Die Gültigkeit kryoskopischer Gleichungen für Lösungen in G<scp>LAUBER</scp>‐Salz‐Schmelzen

Abstract

Abstract Thermodynamics furnish a relation between the depression of the freezing point of a solvent and the depression of its activity, both caused by the addition of small amounts of a solute. In order to carry out cryoscopic determinations of particle weights, the assumption of validity of RAOULT's law is needed in addition to the thermodynamic relation mentioned. For {Na 2 SO 4 , 10 H 2 O} as a solvent, it can be shown theoretically that only particles other than H 2 O, Na + and SO 4 2− give a depression of the transition point at 32,384°. The observed depressions are however somewhat larger on the average than the values calculated thermodynamically using RAOULT's law. Especially cations and anions with high and localized charges are cryoscopically considerably more active than expected according to RAOULT's law. This finding has to be taken into account for the cryoscopic determination of the degree of condensation of polynuclear ionic species.