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Kinetics and mechanism of the reaction of CH 3 O with NO
Author(s) -
Dóbé S.,
Lendvay G.,
Szilágyi I.,
Bérces T.
Publication year - 1994
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.550260903
Subject(s) - chemistry , disproportionation , reaction rate constant , branching fraction , formaldehyde , kinetics , torr , branching (polymer chemistry) , reaction mechanism , chemical kinetics , analytical chemistry (journal) , molecule , photochemistry , thermodynamics , organic chemistry , atomic physics , physics , quantum mechanics , catalysis
The kinetics of the reaction of CH 3 O with NO and the branching ratio for HCHO product formation, obtained as Γ HCHO = (Rate of HCHO formation) / (Rate of CH 3 O decay), have been studied using a discharge flow reactor. Laser induced fluorescence has been used to monitor the decay of the CH 3 O radical and the build‐up of the HCHO product. Overall rate constants and product branching ratios were measured at room temperature over the pressure range of 0.72–8.5 torr He. Three reaction mechanisms were considered which differed in the routes of HCHO formation: (i) direct disproportionation; (ii) via an energized collision complex; or (iii) both reaction routes. It has been shown that data on the pressure dependence of the overall rate constant are not sufficient to distinguish between these mechanisms. In addition, an accurate value of Γ HCHO ∞is required. Analysis of the available experimental data provided 0.0 and about 0.1 as the lower and upper limit for Γ HCHO ∞ , respectively. Since the rate constants derived for CH 3 ONO formation were not sensitive to the value assumed for Γ HCHO ∞ , k CH 3 ONO °= (1.69 ± 0.69) × 10 −29 cm 6 molecule −2 s −1 and k CH 3 ONO ∞= (2.45 ± 0.31) × 10 −11 cm 3 molecule −1 s −1 could be derived. The rate constant obtained for formaldehyde formation when extrapolated to zero pressure is k HCHO 0= (3.15 ± 0.92) × 10 −12 cm 3 molecule −1 s −1 . © 1994 John Wiley & Sons, Inc.