Equilibrium Composition of Sulfur Vapor

Sulfur vapor, as well as the vapors in equilibrium with solid HgS, CdS, ZnS, FeS, SrS, and CaS have been studied mass-spectrometrically. The results indicate the presence of all possible Sn molecules between S2 and S8 in measurable concentration between room temperature and the boiling point of sulfur. Negligible concentrations of S9 and S10 are also observed. The high-temperature experiments are most concordant with the ``high'' value of D0(S2), about 4.4 eV. For the reactions (n/8)S8→Sn(n=2, 3, 4, 5, 6, 7), the enthalpy changes at ∼400°K are ΔH2=23.5 kcal/mole, ΔH3=22.5 kcal/mole, ΔH4=20.5 kcal/mole, ΔH5=14.3 kcal/mole, ΔH6=6.2 kcal/mole, and ΔH7=5.7 kcal/mole.