Kinetic Studies of Chlorine Atom Reactions Using the Turbulent Flow Tube Technique

Abstract

The turbulent flow tube technique has been used to determine the reaction rate constants of chlorine atoms with nitrogen dioxide, methane, and ozone. The Cl + NO2 → ClNO2 reaction was studied at pressures between 50 and 250 Torr. The room temperature rate constant was determined to be (7.2 ± 0.4) × 10-31 cm6 molecule-2 s-1 with Ar as a third body. The Cl + CH4 → HCl + CH3 reaction was studied at temperatures between 181 and 291 K; the experimentally determined Arrhenius expression is given by k = (7.0 ± 1.6) × 10-12 exp[−(1270 ± 60)/T] cm3 molecule-1 s-1. The Cl + O3 → ClO + O2 reaction was studied at temperatures between 206 and 296 K; the resulting Arrhenius expression is given by k = (1.63 ± 0.34) × 10-11 exp[−(91 ± 61)/T] cm3 molecule-1 s-1. The stated uncertainties for the values of rate constants and Arrhenius parameters are reported at the one standard deviation level and represent only the precision of the data. In each case the experimentally determined rate constant is in good agreement with earlier results obtained by using flash-photolysis and conventional low-pressure discharge flow systems. This study demonstrates that the turbulent flow tube method is a viable technique for studying gas phase reaction kinetics over a wide range of temperatures and pressures.