Abstract: | The kinetics of the gas-phase thermal iodination of hydrogen sulfide by I2 to yield HSI and HI has been investigated in the temperature range 555–595 K. The reaction was found to proceed through an I atom and radical chain mechanism. Analysis of the kinetic data yields log k (l/mol·sec) = (11.1 ± 0.18) – (20.5 ± 0.44)/θ, where θ = 2.303 RT, in kcal/mol. Combining this result with the assumption E?1 = 1 ± 1 kcal/mol and known values for the heat of formation of H2S, I2, and HI, ΔHf,2980(SH) = 33.6 ± 1.1 kcal/mol is obtained. Then one can calculate the dissociation energy of the HS? H bond as 90.5 ± 1.1 kcal/mol with the well-known values for ΔHf,2980 of H and H2S. |