Reactions of OH Radicals in the H–NO2 and H–NO2–CO Systems

Abstract

A mass‐spectrometric study has been made of the stoichiometry of the reactions of OH radicals generated by the reaction $$\mathrm{H}+{\mathrm{NO}}_2\to \mathrm{OH}+\mathrm{NO},$$ under conditions similar to those used in some previous studies of the kinetics of the reactions of OH radicals with each other and with CO. Contrary to previous assumptions, when H atoms are initially in excess over NO₂, the reactions $$2\mathrm{OH}\to {\mathrm{H}}_2\mathrm{O}+\mathrm{O},$$ $$\mathrm{O}+\mathrm{OH}\to {\mathrm{O}}_2+\mathrm{H},$$ $$\mathrm{OH}+\mathrm{CO}\to {\mathrm{CO}}_2+\mathrm{H},$$ do not account completely for the decay of OH. An additional reaction occurs which produces water and is probably the first‐order heterogeneous reaction recently postulated on purely kinetic evidence by Breen and Glass [J. Chem. Phys. 52, 1082 (1970)]. When NO₂ is initially in excess over H, a fast reaction takes place involving OH radicals and NO₂ {as first observed by Wilson and O'Donovan [J. Chem. Phys. 47, 5455, (1967)]}. This is probably the reaction $$\mathrm{OH}+{\mathrm{NO}}_2\to {\mathrm{HNO}}_3.$$