Thermodynamic Properties of Hydrogen Fluoride and Fluorine from Spectroscopic Data

Abstract

Spectroscopic data have been used to calculate the free energy, entropy and heat capacity of diatomic HF between 298.1° and 2000°K. The required spectrum of F2 is not known but from electron diffraction data and Badger's rule, enough information has been obtained to make similar calculations to the harmonic oscillator—rigid rotator approximation. The errors in the thermodynamic quantities due to the uncertainties in the vibrational frequency and moment of inertia have been estimated. Combination of these results with thermal data has resulted in values of the free energy change of the reactions: 1/2H2+1/2F2⇌HF and F2⇌2F.