Experimental determination of the equilibrium constant of the reaction CH3 + O2 ⇄ CH3O2 during the gas-phase oxidation of methane

For the experimental determination of the equilibrium constant of the reaction CH₃ + O₂ ? CH₃O₂ (1), the process of methane oxidation has been studied over the temperature range of 706–786 K. The concentration of CH₃O₂ has been measured by the radical freezing method, and that of CH₃ from the rate of accumulation of ethane, assuming that C₂H₆ is produced by the reaction CH₃ + CH₃ → C₂H₆ (2). The equilibrium constant of reaction (1) has been obtained at four temperatures. For the heat of the reaction the value Δ?H₂₉₈ = -32.2 ± 1.5 kcal/mol is recommended.