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Transient oxygen atom yields in H 2 O 2 ignition and the rate coefficient for O + H 2 → OH + H
Author(s) -
Schott Garry L.,
Getzinger Richard W.,
Seitz William A.
Publication year - 1974
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.550060614
Subject(s) - chemistry , combustion , analytical chemistry (journal) , oxygen , arrhenius equation , arrhenius plot , shock wave , atmospheric temperature range , hydrogen , mole fraction , reaction rate constant , thermodynamics , activation energy , kinetics , physics , organic chemistry , chromatography , quantum mechanics
Time‐resolved measurements of the oxygen atom concentration during shock‐wave initiated combustion of low‐density (25 ≤ p ≤ 175 kPa) H 2 O 2 COCO 2 Ar mixtures have been made by monitoring CO + O → CO 2 + hv (3 to 4 eV) emission intensity, calibrated against partial equilibrium conditions attained promptly at H 2 :O 2 = 1. Significant transient excursions (“spikes”) of [O] above constant‐mole‐number partial‐equilibrium levels were found from 1400 to 2000°K for initial H 2 :O 2 ratios of 16 and 10 and below ± 1780°K for H 2 :O 2 = 6; they did not occur in this range for H 2 :O 2 ± 4. Numerical treatment of the H 2 O 2 CO ignition mechanism for our conditions showed [O] to follow a steady‐state trajectory governed by large production and consumption rates from the reactionswith a pronounced maximum in the production term k a [H][O 2 ]. The measured spike concentration data determine k b / k a = 3.6 ± 20%, independent of temperature over 1400 ≤ T ≤ 1900°K, which with well‐established k a data yields\documentclass{article}\pagestyle{empty}\begin{document}$$k_{\rm b} {\rm = 2}{\rm .2 } \times 10^{14} \exp (- 57.5(kJ)/RT){\rm cm}^{\rm 3} /{\rm mole} \cdot {\rm s}$$\end{document} This result reinforces the higher of several recent combustion‐temperature determinations, and its correlation with results below 1000°K produces a distinctly concave upward Arrhenius plot which is closely matched by BEBO transition state calculations.