Kinetics of the reactions of HS and HSO with O3

Niann-Shiah Wang, Carleton J. Howard*

*Corresponding author for this work

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

The kinetics of the reactions of HS and HSO with O3 have been studied in a discharge flow system coupled to a laser magnetic resonance spectrometer: HS + O3 → HSO + O2 (1); HSO + O3 → products (2). Measurements were made at low pressures (1-2.2 Torr) and temperatures between 296 and 431 K. The Arrhenius equation for reaction 1 is k1 = (1.1 ± 0.2) × 10-11 exp((-280 ± 50)/T) cm3 molecule-1 s-1. Our result for k1 at room temperature is somewhat higher than the results of two previous studies. Reaction 2 has more than one channel: HSO + O3 → HS + 2O2 (2a), which regenerates HS, and one or more competing processes that oxidize HSO further: HSO + O3 → products (2α). The complex reaction mechanism required computer simulations to obtain: k2a = (7.0 ± 2.0) × 10-14 at 297 K, (9.0 ± 3.0) × 10-14 at 377 K, and (1.0 ± 0.3) × 10-13 cm3 molecule-1 s-1 at 404 K. The room-temperature k2a value is in reasonable agreement with an earlier study. k was measured directly to be (3.5 ± 1.5) × 10-14 cm3 molecule-1 s-1 at 296 K and (8.6 ± 3.5) × 10-14 cm3 molecule-1 s-1 at 404 K. The deuterium isotope effect on reactions 1 and 2a was also investigated, k(DS + O3 → DSO + O2) = (4.0 ± 0.8) × 10-12 cm3 molecule-1 s-1 and k(DSO + O3 → DS + 2O2) = (3.0 ± 1.0) × 10-14 cm3 molecule-1 s-1 both at 300 K. The application of our results to the oxidation mechanism of H2S in the atmosphere is discussed.

Original languageEnglish
Pages (from-to)8787-8794
Number of pages8
JournalJournal of physical chemistry
Volume94
Issue number25
DOIs
StatePublished - 1 Dec 1990

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