A flash photolysis‐resonance fluorescence study of the reaction of atomic hydrogen with molecular oxygen H + O₂ + M → HO₂ + M

Abstract

Using the technique of flash photolysis-resonance fluorescence, absolute rate constants have been measured for the reaction H + 0 2 + M 4 HOz + M over a temperature range of 220-360°K. Over this temperature range, the data could be fit to an Arrhenius expression of the following form:The units for kAr are cm6/mole-s. At 300°K the relative efficiencies for the third-body gases Ar:He:H2:N2:CH4 were found to be 1.0:0.93:3.0:2.8:22.Wide variations in the photoflash intensity at several temperatures demonstrated that the reported rate constants were measured in the absence of other complex chemical processes.

Kinetics of Nonbranched-Chain Processes of the Free-Radical Addition to Molecules of Alkenes, Formaldehyde, and Oxygen with Competing Reactions of Resulting 1:1 Adduct Radicals with Saturated and Unsaturated Components of the Binary Reaction System

“…11 For example, with the MP2(full)/6-31G(d) method, the difference between the full energies of the cyclic and acyclic HO  can exist in both forms, but the cyclic structure is obviously dominant (87%, K eq = 6.5) [85]. Reaction 4 and, to a much lesser degree, reaction 6 inhibit the chain process, because they lead to inefficient consumption of its main participants - The hydrogen molecule that results from reaction 5 in the gas bulk possesses an excess energy, and, to acquire stability within the approximation used in this work, it should have time for deactivation via collision with a particle M capable of accepting the excess energy [87]. To simplify the form of the kinetic equations, it was assumed that the rate of the bimolecular deactivation of the molecule substantially exceeds the rate of its monomolecular decomposition, which is the reverse of reaction 5 [2].…”

“…The kinetic description of the noncatalytic oxidation of hydrogen, including in an inert medium [87], in terms of the simplified scheme of free-radical nonbranched-chain reactions (Scheme 4), which considers only quadratic-law chain termination and ignores the surface effects [47], at moderate temperatures and pressures, in the absence of transitions to unsteady-state critical regimes, and at a substantial excess of the hydrogen concentration over the oxygen concentration was obtained by means of quasi-steady-state 13 It is impossible to make a sharp distinction between the two-step bimolecular interaction of three species via the equilibrium formation of the treatment, as in the previous studies on the kinetics of the branchedchain free-radical oxidation of hydrogen [76], even though the applicability of this method in the latter case under unsteady states conditions was insufficiently substantiated. The method was used with the following condition: 14 .…”

Competition Kinetics of the Non-branched-Chain Processes of Free Radical Addition to the C=C, C=O, and O=O Bonds of Molecules<SUP>1</SUP>

“…Reaction 4 and, to a much lesser degree, reaction 6 inhibit the chain process, because they lead to inefficient consumption of its main participants - The hydrogen molecule that results from reaction 5 in the gas bulk possesses an excess energy, and, to acquire stability within the approximation used in this work, it should have time for deactivation via collision with a particle M capable of accepting the excess energy [87]. To simplify the form of the kinetic equations, it was assumed that the rate of the bimolecular deactivation of the molecule substantially exceeds the rate of its monomolecular decomposition, which is the reverse of reaction 5 [2].…”

Competition Kinetics of the Nonbranched‐Chain Addition of Free Radicals to Olefins, Formaldehyde, and Oxygen

“…The hydrogen molecule that results from reaction (5) in the gas bulk possesses an excess energy, and, to acquire stability within the approximation used in this work, it should have time for deactivation via collision with a particle M capable of accepting the excess energy [74]. To simplify the form of the kinetic equations, it was assumed that the rate of the bimolecular deactivation of the molecule substantially exceeds the rate of its monomolecular decomposition, which is the reverse of reaction (5) [2].…”

“…The kinetic description of the noncatalytic oxidation of hydrogen, including in an inert medium [74], in terms of the simplified scheme of free-radical nonbranched-chain reactions (Scheme 4), which considers only quadratic-law chain termination and ignores the surface effects [46], at moderate temperatures and pressures, in the absence of transitions to unsteady-state critical regimes, and at a substantial excess of the hydrogen concentration over the oxygen concentration was obtained by means of quasi-steady-state treatment, as in the previous studies on the kinetics of the branchedchain free-radical oxidation of hydrogen [62], even though the applicability of this method in the latter case under unsteady-states conditions was insufficiently substantiated. The method was used with the following condition: 12 k 6 = 2k 5 2k 7 (see Section 1).…”