TY - JOUR
T1 - Kinetic (T = 201–298 K) and equilibrium (T = 320–420 K) measurements of the C3H5 + O2⇔ C3H5O2 reaction
AU - Rissanen, Matti P.
AU - Amedro, Damien
AU - Eskola, Arkke J.
AU - Kurten, Theo
AU - Timonen, Raimo S.
PY - 2012/4/26
Y1 - 2012/4/26
N2 - The kinetics and equilibrium of the allyl radical reaction with molecular oxygen have been studied in direct measurements using temperature-controlled tubular flow reactor coupled to a laser photolysis/photoionization mass spectrometer. In low-temperature experiments (T = 201-298 K), association kinetics were observed, and the measured time-resolved C 3H 5 radical signals decayed exponentially to the signal background. In this range, the determined rate coefficients exhibited a negative temperature dependence and were observed to depend on the carrier-gas (He) pressure {p = 0.4-36 Torr, [He] = (1.7-118.0) × 10 16 cm -3}. The bimolecular rate coefficients obtained vary in the range (0.88-11.6) × 10 -13 cm 3 s -1. In higher-temperature experiments (T = 320-420 K), the C 3H 5 radical signal did not decay to the signal background, indicating equilibration of the reaction. By measuring the radical decay rate under these conditions as a function of temperature and following typical second- and third-law procedures, plotting the resulting ln K p values versus 1/T in a modified van't Hoff plot, the thermochemical parameters of the reaction were extracted. The second-law treatment resulted in values of ΔH298 ° = -78.3 ± 1.1 kJ mol -1 and ΔS298 ° = -129.9 ± 3.1 J mol -1 K -1, with the uncertainties given as one standard error. When results from a previous investigation were taken into account and the third-law method was applied, the reaction enthalpy was determined as ΔH298 ° = -75.6 ± 2.3 kJ mol -1.
AB - The kinetics and equilibrium of the allyl radical reaction with molecular oxygen have been studied in direct measurements using temperature-controlled tubular flow reactor coupled to a laser photolysis/photoionization mass spectrometer. In low-temperature experiments (T = 201-298 K), association kinetics were observed, and the measured time-resolved C 3H 5 radical signals decayed exponentially to the signal background. In this range, the determined rate coefficients exhibited a negative temperature dependence and were observed to depend on the carrier-gas (He) pressure {p = 0.4-36 Torr, [He] = (1.7-118.0) × 10 16 cm -3}. The bimolecular rate coefficients obtained vary in the range (0.88-11.6) × 10 -13 cm 3 s -1. In higher-temperature experiments (T = 320-420 K), the C 3H 5 radical signal did not decay to the signal background, indicating equilibration of the reaction. By measuring the radical decay rate under these conditions as a function of temperature and following typical second- and third-law procedures, plotting the resulting ln K p values versus 1/T in a modified van't Hoff plot, the thermochemical parameters of the reaction were extracted. The second-law treatment resulted in values of ΔH298 ° = -78.3 ± 1.1 kJ mol -1 and ΔS298 ° = -129.9 ± 3.1 J mol -1 K -1, with the uncertainties given as one standard error. When results from a previous investigation were taken into account and the third-law method was applied, the reaction enthalpy was determined as ΔH298 ° = -75.6 ± 2.3 kJ mol -1.
U2 - 10.1021/jp209977h
DO - 10.1021/jp209977h
M3 - Journal article
C2 - 22500811
SN - 1089-5639
VL - 116
SP - 3969
EP - 3978
JO - Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
JF - Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
IS - 16
ER -