Absolute rate constants for the reactions O( 3 P ) atoms with HCl and HBr

A flow tube method has been used to determine rate constants for the elementary reactions:Oxygen atoms were produced by adding a small excess of NO to a stream of partially dissociated nitrogen, and their reaction with hydrogen halide was monitored by observing the intensity of the NO + O afterglow. Experiments were carried out at temperatures from 293 to 440°K with HCl, and from 267 to 430°K with HBr. The role of secondary reactions was minimised and the residual effects were allowed for. The rate constants for the primary reactions could be matched by Arrhenius expressions:\documentclass{article}\pagestyle{empty}\begin{document}$$ k_{1a} = 2.5\left({_ - ^ + } \right.\left. {{}_{0.8}^{1.2} } \right) \times 10^{ - 12} \,{\rm exp}\frac{{{\rm ( - 5}{\rm .9} \pm {\rm 0}{\rm .3}\,{\rm kcal/mole)}}}{{RT}} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ k_{1b} = 4.0( \pm 0.7) \times 10^{ - 12} \,{\rm exp}\frac{{{\rm ( - 2}{\rm .7} \pm {\rm 0}{\rm .1}\,{\rm kcal/mole)}}}{{RT}} $$\end{document} where the units are cm 3 /molec·sec and the errors correspond to a standard deviation.