HCl Yield from the OH + ClO Reaction at Temperatures between 218 and 298 K

Abstract

The yield of HCl from the OH + ClO reaction has been determined at 1 Torr total pressure by using the discharge-laminar-flow technique with resonance fluorescence, infrared diode laser spectrometry, and ultraviolet absorption spectrometry detection methods. A known amount of OH is added to a large excess of ClO and the reaction is allowed to go to completion. Under these conditions, the yield is just the ratio of [HCl] produced to initial [OH]. The yield or branching ratio measurement reduces to a measurement of two concentrations; knowledge of the total rate constant or of the branching rate constants is not required. The results are 9.0 ( 4.8% independent of temperature between 218 and 298 K. The errors given are two standard deviations. The results are also independent of the OH source: F + H2O or H + NO2. Interference from secondary chemistry is minimized by extrapolating a plot of observed yields to zero initial [OH]. Numerical simulations are used only to check for interference from secondary chemistry and to validate the extrapolation procedure.