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 logKp
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.