TITLE

Thermodynamic and kinetic properties of the reaction Cl+O2+M=ClOO+M in the range 160–300 K and 1–1000 bar

AUTHOR(S)
Baer, S.; Hippler, H.; Rahn, R.; Siefke, M.; Seitzinger, N.; Troe, J.
PUB. DATE
November 1991
SOURCE
Journal of Chemical Physics;11/1/1991, Vol. 95 Issue 9, p6463
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
The reaction Cl+O2+M[larger_closed_square]ClOO+M was studied by laser flash photolysis in the bath gases M=He, Ar, N2, and O2 over the temperature range 160–300 K and the pressure range 1–1000 bar. UV absorptions of ClOO were monitored, a maximum absorption cross section of σ(248 nm)=3.4×10-17 cm2 was determined. An expression for the equilibrium constant Kp =5.3×10-6 exp(+23.4 kJ mol-1/RT) bar-1 was derived between 180 and 300 K, which, by a third law analysis, yields ΔH○0 =-20.2±0,2 kJ mol-1. Limiting low pressure rate coefficients for Cl+O2 recombination of k0=[He]8.8×10-34(T/300 K)-3.0, k0=[O2]1.6×10-33(T/300 K)-2.9, k0=[N2]1.4×10-33(T/300 K)-3.9 cm6 s-1 were obtained over the range 160–260 K, as well as k0 (160 K)=[Ar]2.2×10-32 cm6 s-1. Rate constants for the reactions Cl+ClOO→Cl2+O2 or 2ClO, ClOO+ClOO→products, and ClOO+Cl2→Cl2O+ClO were also derived. The recombination Cl+O2(+M)→ClOO(+M) at pressures above 10 bar shows a transition to a high pressure plateau and, at pressures above 200 bar, to diffusion control. It is suggested that, like O+O2(+M)→O3(+M), the reaction is governed by a radical complex mechanism.
ACCESSION #
7619495

 

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