Rates of CO + OH and H2 + OH over an extended temperature range

Using a fast flow reactor with a fixed ESR detector and movable NO₂ source (for generation of OH by the H + NO₂ reaction) it was possible to measure the rate constants for $\mathrm{CO}+\mathrm{OH}\to {\mathrm{CO}}_2+\mathrm{H}{\mathrm{(k}}_1)$ and ${\mathrm{H}}_2+\mathrm{OH}\to {\mathrm{H}}_2\mathrm{O}+\mathrm{H}{\mathrm{(k}}_4)$ under pseudo‐first‐order conditions with negligible OH loss by $\mathrm{OH}+\mathrm{OH}\to {\mathrm{H}}_2\mathrm{O}+\mathrm{O}$ . Small losses of OH on the reactor wall were accurately taken into account, and data over an extended temperature range were obtainable. Both reactions show definite curvature in their Arrhenius plots over the range of direct measurement (298–915°K for k₁ and 298–745°K for k₄). Good agreement is found in comparisons with other well‐defined results. In the case of Reaction (4), a definitive experiment was performed to show that by far the dominant reaction path involves breaking the H₂ bond, rather than the OH bond as in Reaction (1).