Equilibrium hydrogen fluoride pressures over metal hydrofluorides, fluorophosphates and metal difluoride systems

Abstract

The equilibrium pressures of hydrogen fluoride gas over barium, sodium, potassium and caesium monohydrofluorides have been measured in the general pressure range from 0.01 Pa to 1000 Pa. Nitrogen gas is transported through the powdered solid, then the acquired HF gas is absorbed on membrane filter papers for subsequent analysis with a fluoride ion specific electrode.

By similarly using nitrogen with water vapour the equilibrium hydrogen fluoride pressures generated by the hydrolysis of sodium, potassium, barium and lead monofluorophosphates, and zinc, lead and cobalt difluorides were studied.

The results for all systems are represented by linear logK_p against reciprocal temperature equations from which, where the corresponding chemical reaction has been identified with considerable certainty, the reaction enthalpy, entropy and other thermodynamic quantities have been deduced.