Shock Tube Studies of Sulfur Tetrafluoride Dissociation

Shock tube studies of SF₄ dissociation have been made in the temperature range 1650–1950°K. Rate constants for the initial fragmentation of SF₄ have been determined from ir measurements and are explainable in terms of classical unimolecular reaction kinetics. The data were correlated with the Rice–Ramsperger–Kassel (RRK) theory; the values used were 79.0 kcal/mole for the SF₃–F bond strength, 10^13.63 sec⁻¹ for the pre‐exponential $A$ factor, ${\lambda }_D{\sigma }_m^2{\text{\hspace{0.17em}=\hspace{0.17em}5.79\hspace{0.17em}×\hspace{0.17em}10}}^{\text{−16}}{\mathrm{cm}}^2$ , and $\text{S\hspace{0.17em}=\hspace{0.17em}6}$ . Kinetic rates obtained from exponentially decaying radiation at 12.6 $\mu$ and temperatures of 2050–2800°K are attributed to SF₃ and lie near the low‐pressure limit of unimolecular reactions. The SF₃ dissociation rates can be described by ${\text{k\hspace{0.17em}=\hspace{0.17em}4.29\hspace{0.17em}×\hspace{0.17em}10}}^{15}\exp \text{(−\hspace{0.17em}71.8\hspace{0.17em}/\hspace{0.17em}RT)}\mathrm{cc}/\mathrm{mole·sec}$ , where $R$ is in kilocalories per mole·degree Kelvin.