The photosynthesis of hydrogen chloride. III.—Mixtures containing oxygen

The inhibiting action of oxygen in hydrogen-chlorine mixtures was first observed by Bunsen and Roscoe, and has been generally confirmed by all later workers, but the exact part played by oxygen is still attended by some uncertainties. Chapman and MacMahon found the sensitivity of stoichiometric mixtures of hydrogen and chlorine at atmospheric pressure to be inversely proportional to the oxygen content. In like manner, Bodenstein and Dux, for stoichiometric mixtures and concentrations of oxygen up to 22.5 mm. Hg, state that the rate of formation of HCI under such conditions is given by d[HCI] / dt = k[Cl2]2 / [O2] for constant conditions of incident light intensity. The results of all workers are in agreement with the statement that in the presence of oxygen the rate of reaction is proportional to the first power of the light absorbed, and thus that the quantum efficiency is independent of variation of the intensity of light.