Rate coefficients and Arrhenius parameters for the reactions between chloroethenes and the nitrate radical

Abstract

Rate coefficients for the reactions between NO₃ and the chloroethenes have been determined by the fast-flow-discharge technique and by the relative rate method in a static reactor employing FTIR detection. The relative rate experiments were performed at 298 ± 2 K and 1013 ± 3 mbar in a nitrogen atmosphere with excess ethane as a chlorine scavenger. The flow tube experiments were carried out under pseudo-first-order conditions in NO₃. The temperature dependence of the NO₃ reactions with chloroethene and trichloroethene was investigated over a temperature range of ca. 100 K, and their rate coefficients were fitted to Arrhenius expressions. A comparison between our measured rate coefficient data for the NO₃ reaction with chloroethenes reveals that the relative rate results are up to 20% lower than those from the fast-flow-discharge experiments. Possible secondary reactions in the flow tube are discussed.