RATE COEFFICIENTS AND ARRHENIUS PARAMETERS FOR THE REACTIONS BETWEEN CHLOROETHENES AND THE NITRATE RADICAL

Rate coefficients for the reactions between NO3 and the chloroethenes have been determined by the fast-flow-discharge technique and by the r elative 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 scaven ger. The how tube experiments were carried out under pseudo-first-orde r conditions in NO3. The temperature dependence of the NO3 reactions w ith chloroethene and trichloroethene was investigated over a temperatu re range of ca. 100 K, and their rate coefficients were fitted to Arrh enius 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-discha rge experiments. Possible secondary reactions in the flow tube are dis cussed.