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Low‐pressure thermal decomposition of ONBr and ONCl in shock waves
Author(s) -
Maloney K. K.,
Palmer H. B.
Publication year - 1973
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550050611
Subject(s) - chemistry , arrhenius equation , thermodynamics , shock wave , thermal decomposition , activation energy , dissociation (chemistry) , argon , reaction rate constant , shock tube , bond dissociation energy , decomposition , kinetics , organic chemistry , classical mechanics , physics
Abstract Rate constants for the low‐pressure unimolecular decomposition of ONBr and ONCl in an argon bath have been determined at temperatures in the vicinity of 1000°K. Both molecules exhibit the usual depression of the observed activation energy below the bond dissociation energy. The Arrhenius expressions obtained are (units of cc mole −1 sec −1 ):\documentclass{article}\pagestyle{empty}\begin{document}$$ ONBr - Ar:\log k = (15.06 \pm 0.27) - (25.06 \pm 1.13)kcalmole^{ - 1} /\theta $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ ONCl - Ar:\log k = (15.95 \pm 0.52) - (43.79 \pm 2.04)kcalmole^{ - 1} /\theta $$\end{document}Treatment of the data by the classical RRK theory yields s ≅ 2.7 ± 1 for ONCl and 3.0 ± 0.6 for ONBr. Coupling the shock tube results for ONCl with lower‐temperature data from Ashmore and Burnett [3], one obtains s ≅ 2.5 ± 0.5 and λ ≈ 1. If it is assumed that s is also 2.5 for ONBr, then one finds the surprising (but tentative) result that λ ONClAr/λONBrAr ≈ 3 to 4.