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Title: Kinetic Study of the Reactions of CaO with H2O, CO2, O2, and O3: Implications for Calcium Chemistry in the Mesosphere
Journal: J. Phys. Chem. A
Volume: 105
Page(s): 7047 - 7056
Year: 2001
Reference type: Journal article
Squib: 2001PLA/ROL7047-7056
Reaction:
CO2 + CaO → CaCO3
Reaction order:
2
Temperature:
213 - 480
K
Pressure: 3.73E-3 - 1.55E-2 bar
Rate expression:
7.97x10-10 [cm3/molecule s] e-1580 [J/mole]/RT
Uncertainty:
1.22
Bath gas:
N2
Category: Experiment
Data type:
RRK(M) extrapolation
Pressure dependence:
Rate constant is high pressure limit
Experimental procedure:
Static or low flow - Data taken vs time
Excitation technique:
Flash photolysis (laser or conventional)
Time resolution:
In real time
Analytical technique:
Laser induced fluorescence
Comments:
CaO was generated by 193 nm excimer laser photolysis of Ca(acac)2 calclium acetyl acetonate. The time decay of CaO was monitored by LIF pumping at 385.9 nm and detecting at >693 nm. O3 was monitored by absorption at 253.7 nm using a mercury lamp. Absolute uncertainties in rate constants were estimated at 22%. RRKM analysis was used to extrapolate to high and low pressure rate expressions. Reactions appeared to be slightly in fall-off, thus high pressure rate coefficients should be good, while low pressure rate parameters are less certain. Quantum DFT calculations B3LYP/6-311+G(2d,p) to calculated geometries, vibrational frequencies, and energies of reactants, products, and transition states and to determine reaction pathways.
View full bibliographic record.
Rate constant values calculated from the Arrhenius expression:
| T (K) | k(T) [cm3/molecule s] |
|---|---|
| 213 | 3.27E-10 |
| 225 | 3.43E-10 |
| 250 | 3.73E-10 |
| 275 | 3.99E-10 |
| 300 | 4.23E-10 |
| 325 | 4.44E-10 |
| 350 | 4.63E-10 |
| 375 | 4.80E-10 |
| 400 | 4.96E-10 |
| 425 | 5.10E-10 |
| 450 | 5.23E-10 |
| 475 | 5.34E-10 |
| 480 | 5.36E-10 |