Campbell, I.M., and Handy, B.J. (1978)
Studies of Reactions of Atoms in a Discharge Flow Stirred Reactor
J. Chem. Soc. Faraday Trans. 1 1978, 74, 316.
Abstract
A discharge-flow stirred reaction system has been used to measure the rate
constant for the reaction (3) over the
temperature range 315-490 K. Below 350 K, carbon monoxide (¾5%) was added to
generate the bluish O+CO chemiluminescence, the intensity of which served to
measure oxygen atom decay rates. An expression for k(3) shown below summarised
the measurements above 350 K, but sharp positive deviation was found in the
Arrhenius plot of k(3) below this temperature, for which quantum mechanical
tunnelling in the transition state provides a likely interpretation.
At 425 K in O/H2/N2 or Ar systems with CO mole fractions up to 60%, HCO radicals
are synthesized by the recombination reaction (-167) and destroyed by the reactions
(55), (13), and (14).
In systems where large mole fractions of CO were present, the [H]/[O] ratios were
established from the linear increase in the oxygen atom decay rate from entry to
exit with increasing additions of nitric oxide, using the O+CO chemiluminescence
as indicator. In 27 experiments in N2 carriers and 36 experiments in Ar carriers
with 90¾[CO]/[O]¾950 and 0.2¾[H]/[O]¾3, the measured oxygen
atom decay parameters were analyzed iteratively by computer. Combination of these
two types of experimental results yielded k(-167) shown below for 425 K, the
k(-167,Ar) in agreement with temperature extrapolated literature values. A
well-defined ratio A=k(55)/{k(13)+k(14)}=2.1±0.3 was also obtained, together
with an estimate of B=k(13)/k(14)=0.4±0.2. A simplified collisional model is
used to interpret the values of A and B.
REACTION RATE COEFFICIENTS SUGGESTED IN THIS WORK:
GRI-Mech
Number
('-' sign
means
reverse) |
Reaction |
Rate Coefficient
A T^n exp(-E/RT) |
Temperature
Range
(K) |
A
(mol,cm3,s) |
n
(T in K) |
E
(cal/mol) |
| 3 |
O + H2 -> H + O2 |
3.1E+13 |
|
9835 |
350-490 |
| -167* |
H + CO + M -> HCO + M |
1.44E+14 |
|
|
425 |
| -167** |
H + CO + M -> HCO + M |
9.7E+13 |
|
|
425 |
* M = N2, dimensions = cm^6/mol^2 s
** M = Ar, dimensions = cm^6/mol^2 s