Photochemical Reaction between Hydrogen and Chlorine in the Presence of Oxygen

Abstract

IT has been generally assumed that the hydrogen chloride produced when a mixture of hydrogen and chlorine is illuminated has no effect on the velocity of reaction. If, however, the magnitudes of the Draper effects are considered for two reaction mixtures which do not differ in hydrogen, chlorine, and oxygen concentrations, but only in the circumstance that one (a) contains no hydrogen chloride, and the other (b) an amount of hydrogen chloride equal, say, to that of the concentration of chlorine, then the magnitude of the Draper effect in (a) can be observed to fall off very rapidly on illumination, while that of (b) shows no such rapid initial fall but is always smaller than the initial value in the case of (a). Indications of a rapid initial fall in reaction velocity in mixtures containing initially no hydrogen chloride can indeed be recognised in the ‘velocity coefficients’ given by several workers; for example, by Bodenstein and Dux.¹