VAPORIZATION CHEMISTRY AND THERMODYNAMICS OF TITANIUM MONOSULFIDE BY THE COMPUTER-AUTOMATED SIMULTANEOUS KNUDSEN-TORSION EFFUSION METHOD

The computer-automated simultaneous Knudsen-torsion effusion method was applied to establish the vaporization thermodynamics of titanium monosulfide, TiS(s), from 2039 to 2168 K. This study was the first application of that method above 2000 K. Titanium monosulfide was prepared by a method designed to prevent contamination by oxygen. Inductive interactions of the torsion pendulum with electrical current in the furnace were large and required accurate accounting in the differential equation of motion of the pendulum. Previous mass-spectrometric results were used to calculate molecular weights for Knudsen-effusion calculations and to partition the vapor into its constituents for interpretation of torsion-effusion results. The third-law enthalpy of vaporization at 298 K to form TiS(g) is 613 ± 3 kJ/mol and to form 1 mol each of Ti(g) and S(g) it is 1030 ± 6 kJ; the dissociation enthalpy at 298 K of TiS(g) is 418 ± 3 kJ/mol. The present values are compared with previous results by mass spectrometry and target collection. Selected values from a recent compilation are found to be slightly incorrect; uncertainties in the values are diminished by as much as a factor of 14. © 1979 American Chemical Society.