Kinetics of the reaction of CCl sub 3 + Br sub 2 and thermochemistry of CCl sub 3 radical and cation
- National Inst. of Standards and Technology, Gaithersburg, MD (United States)
- Catholic Univ. of America, Washington, DC (United States)
The rate constant of the CCl{sub 3} + Br{sub 2} {yields} CCl{sub 3}Br + Br reaction was determined as a function of temperature between 300 and 532 K and fit to an Arrhenius expression: k{sub 1} (L mol{sup {minus}1} s{sup {minus}1}) = (1.8 {plus minus} 0.4) {times} 10{sup 8} exp(({minus}1.43 {plus minus} 0.29) kcal mol{sup {minus}1}/RT). The reaction was studied in a tubular flow reactor by using laser photolysis to produce the CCl{sub 3} reactant and photoionization mass spectrometry to monitor CCl{sub 3} in time-resolved experiments. Previously published kinetic data were reevaluated to obtain k{sup {minus}1}, the rate constant for the reverse reaction, and recent spectroscopic data were used to calculate accurate entropies and heat capacities. The values of k{sub {minus}1}, k{sub 1}, and these calculated thermodynamic properties were used in a third law determination to obtain {Delta}H{degree}{sub f,298.15}(CCl{sub 3}) = 17.0 {plus minus} 0.6 kcal mol{sup {minus}1} and {Delta}H{degree}{sub f,0}(CCl{sub 3}) = 16.7 {plus minus} 0.6 kcal mol{sup {minus}1}. This information was combined with spectroscopic data on CCl{sub 3}{sup +} to obtain {Delta}H{degree}{sub f,298.15}(CCl{sub 3}{sup +}) = 205.2 {plus minus} 0.6 kcal mol{sup {minus}1} and {Delta}H{degree}{sub f,0}(CCl{sub 3}{sup +}) = 203.7 {plus minus} 0.6 kcal mol{sup {minus}1}. Bond energies of several relevant compounds and tables of thermodynamic functions for CCl{sub 3} and CCl{sub 3}{sup +} are presented. An improved heat of formation for the CCl{sub 3}O{sub 2} radical, {Delta}H{degree}{sub f,298.15}(CCl{sub 3}O{sub 2}) = 2.7 {plus minus} 1.1 kcal mol{sup {minus}1}, is also reported.
- OSTI ID:
- 5890244
- Journal Information:
- Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:11; ISSN 0022-3654; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
54 ENVIRONMENTAL SCIENCES
540120 -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
ALKYL RADICALS
ARRHENIUS EQUATION
ATMOSPHERIC CHEMISTRY
BROMINE
CATIONS
CHARGED PARTICLES
CHEMICAL BONDS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
CHLORINATED ALIPHATIC HYDROCARBONS
DATA
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ELEMENTS
ENTROPY
EQUATIONS
EXPERIMENTAL DATA
HALOGENATED ALIPHATIC HYDROCARBONS
HALOGENS
INFORMATION
IONIZATION
IONS
KINETICS
LASER RADIATION
MASS SPECTROSCOPY
MATHEMATICAL MODELS
NONMETALS
NUMERICAL DATA
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOIONIZATION
PHOTOLYSIS
PHYSICAL PROPERTIES
RADIATIONS
RADICALS
REACTION KINETICS
SPECIFIC HEAT
SPECTROSCOPY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
THERMODYNAMIC PROPERTIES
TIME DEPENDENCE