A HIGH-TEMPERATURE PHOTOCHEMICAL KINETICS STUDY OF THE O + HCL REACTION FROM 350-K TO 1480-K

Rate coefficients for the O + HCl reaction have been measured by using two differently designed high-temperature photochemistry (HTP) reactors. Measurements were made under pseudo-first-order conditions, [O] ≪ [HCl], at temperatures from 350 to 1480 K and pressures from 100 to 613 Torr. Ground-state O atoms were generated by flash photolysis of O2 or CO2 and monitored by time-resolved atomic resonance fluorescence with pulse counting. The data show non-Arrhenius behavior and are well fitted by the empirical expression k(T) = 7.5 × 10-22T3.13 exp(-1550 K/T) cm3 molecule-1 s-1. Combining the present data with published measurements in the 350-720 K range yields k(T) = 5.6 × 10-21T2.87 exp(-1766 K/T) cm3 molecule-1 s-1 for the 350-1480 K range with a 2σ confidence interval of 23%, which figure includes a liberal allowance for potential systematic errors. The contribution to the observed reaction rates of vibrationally excited HCl at equilibrium concentrations is inferred to be negligible. The experimental results are consistent with transition-state theory (TST) calculations. © 1990 American Chemical Society.