Rate Constants for CF3 + H2 → CF3H + H and CF3H + H → CF3 + H2 Reactions in the Temperature Range 1100−1600 K

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 1998-09, Vol.102 (39), p.7668-7673
• Main Authors: Hranisavljevic, J, Michael, J. V
• Format: Article
• Language: English
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp982432q

The shock tube technique coupled with H-atom atomic resonance absorption spectrometry has been used to study the reactions (1) CF3 + H2 → CF3H + H and (2) CF3H + H → CF3 + H2 over the temperature ranges 1168−1673 K and 1111−1550 K, respectively. The results can be represented by the Arrhenius expressions k 1 = 2.56 × 10-11 exp(−8549K/T) and k 2 = 6.13 × 10-11 exp(−7364K/T), both in cm3 molecule-1 s-1. Equilibrium constants were calculated from the two Arrhenius expressions in the overlapping temperature range, and good agreement was obtained with the literature values. The rate constants for reaction 2 were converted into rate constants for reaction 1 using literature equilibrium constants. These data are indistinguishable from direct k 1 measurements, and an Arrhenius fit for the joint set is k 1 = 1.88 × 10-11 exp(−8185K/T) cm3 molecule-1 s-1. The CF3 + H2 → CF3H + H reaction was further modeled using conventional transition-state theory, which included ab initio electronic structure determinations of reactants, transition state, and products.