Thermal decomposition kinetics of CH/sub 3/O/sub 2/NO/sub 2/

Journal Article · Thu May 13 04:00:00 EDT 1982 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100207a022· OSTI ID:6594084

Bahta, A; Simonaltis, R; Heicklen, J

The thermal decomposition rate of CH/sub 3/O/sub 2/NO/sub 2/ was studied over the temperature range 256-268 K at approx.350 torr total pressure and over the pressure range 50-720 torr at 263 K by perturbation of the equilibrium CH/sub 3/O/sub 2/ + NO/sub 2/ (+M) ..-->.. reverse arrow CH/sub 3/O/sub 2/NO/sub 2/ (+M) (3, -3) with NO, CH/sub 3/O/sub 2/ + NO ..-->.. CH/sub 3/O + NO/sub 2/ (4). The CH/sub 3/O/sub 2/NO/sub 2/ was generated in situ by the photolysis of Cl/sub 2/ in the presence of O/sub 2/, CH/sub 4/, and NO/sub 2/. The decomposition kinetics were monitored in the presence of NO by the change in ultraviolet absorption at 250 nm. The Arrhenius expression obtained for the thermal decomposition is k/sub -3/ = 6 x 10/sup 15/ exp)-(21100 +/- 1500)/RT)s/sup -1/ at approx. = 350 torr total pressure (mostly CH/sub 4/) where R = 1.987 cal/(mol K). The uncertainty in the Arrhenius parameters can be greatly reduced by combining this expression with data for k/sub 3/ and thermodynamics data to give k/sub -3/ = (6 +/- 3) x 10/sup 15/ exp)-(213000 +/- 300)/RT) s/sup -1/ at approx. = 350 torr total pressure. Computations based on the pressure dependence of the forward reaction give k/sub -3//sup infinity/ = 2.1 x 10/sup 16/ exp)-21700 +/- 300)RT)s/sup -1/ and k/sub -3//sup 0/ = 3.3 x 10/sup -4/ exp)-20150 +/- 300)/RT)cm/sup 3/s/sup -1/. At 263.3 K the equilibrium constant K/sub 3,-3/)263.3 K) is determined to be (2.68 +/- 0.26) x 10/sup -10/ cm/sup 3/. In the stratosphere the CH/sub 3/O/sub 2/NO/sub 2/ lifetime will be controlled by photodissociation. Approximate calculations indicate that CH/sub 3/O/sub 2/NO/sub 2/ may play a role in the NO/sub x/ budget of the lower stratosphere.

• Research Organization: The Pennsylvania State University, University Park
• OSTI ID: 6594084
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 86:10; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400200* -- Inorganic
Organic
& Physical Chemistry
500100 -- Environment
Atmospheric-- Basic Studies-- (-1989)
54 ENVIRONMENTAL SCIENCES
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMPLEXES
DATA
DECOMPOSITION
DIAGRAMS
EARTH ATMOSPHERE
EXPERIMENTAL DATA
INFORMATION
KINETICS
LIFETIME
LOW TEMPERATURE
NITRO COMPOUNDS
NITROGEN COMPOUNDS
NITROGEN OXIDES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PEROXY RADICALS
PRESSURE DEPENDENCE
PYROLYSIS
RADICALS
REACTION KINETICS
STRATOSPHERE
TEMPERATURE DEPENDENCE
THERMOCHEMICAL PROCESSES