Kinetics of the NH[sub 2] + NO reaction. Effects of temperature on the total rate constant and the OH/H[sub 2]O branching ratio
- Emory Univ., Atlanta, GA (United States)
The rate constant for the reaction of NH[sub 2] with NO has been measured between 297 and 673 K using the cavity-ring-down technique to monitor the disappearance of the NH[sub 2] radical. The measured bimolecular rate constant can be effectively represented by the expression k[sup II] = (2.2 [+-] 0.7) x 10[sup [minus]12] exp[525 [+-] 80/T] cm[sup 3]/s, which agrees reasonably well with the results of several other recent measurements employing various diagnostic methods. A multichannel RRKM calculation has been carried out to account for the observed negative temperature dependence and the product branching ratio, OH/H[sub 2]O, based on Walch's recent potential energy surface data for various transition states and stable intermediates leading to the formation of the OH and H[sub 2]O products. The predicted temperature dependencies agree reasonably well with experimental observations. We have also performed kinetic modeling using a set of of reactions involving H, NH[sub 3], NH[sub 2], NO, and their anticipated products. The result of the modeling aided by sensitivity analysis suggests that the unknown [open quotes]third channel[close quotes] responsible for the decline of the ([OH] + [H[sub 2]O])/[NH[sub 2]][sub 0] ratio at high temperatures (ref 23) may result from secondary reactions which produce neither OH nor H[sub 2]O. These reactions include NH[sub 2] + H [yields] NH + H[sub 2] and NH[sub 2] + NH[sub 2] [yields] NH + NH[sub 3]. 69 refs., 9 figs., 5 tabs.
- OSTI ID:
- 7165830
- Journal Information:
- Journal of Physical Chemistry; (United States), Vol. 98:15; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
54 ENVIRONMENTAL SCIENCES
CHEMICAL REACTION KINETICS
MATHEMATICAL MODELS
TEMPERATURE DEPENDENCE
NITRIC OXIDE
CHEMICAL REACTIONS
RADICALS
AMMONIA
EXPERIMENTAL DATA
SENSITIVITY ANALYSIS
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
THEORETICAL DATA
CHALCOGENIDES
DATA
HYDRIDES
HYDROGEN COMPOUNDS
INFORMATION
KINETICS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NITROGEN OXIDES
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
REACTION KINETICS
TEMPERATURE RANGE
400201* - Chemical & Physicochemical Properties
540120 - Environment
Atmospheric- Chemicals Monitoring & Transport- (1990-)