IUPAC Subcommittee on Gas Kinetic Data Evaluation

Providing evaluated kinetic data on the web since 1999.

IUPAC Subcommittee on Gas Kinetic Data Evaluation

Website: http://www.iupac-kinetic.ch.cam.ac.uk/ See website for latest evaluated data. Datasheets can be downloaded for personal use only and must not be retransmitted or disseminated either electronically or in hardcopy without explicit written permission.

This datasheet last evaluated: 2002-03-09 ; last change in preferred values: 2002-03-09 ; last peer-reviewed publication: 2004-03-09


HO2 + NO2 + MHO2NO2 + M(1) Δ Hο = -100.5 kJ mol-1

Rate Coefficient Data: Low-pressure rate coefficients

Absolute Rate Coefficients

Rate Coefficient (k0) / Temperature / ReferenceTechniques and Comments
cm3molecule-1s-1Kelvin
(2.09 ± 0.52)×10 -31 [N 2 ]300Howard, 1977DF-LMR (a)
(2.5 ± 0.5)×10 -31 [N 2 ]283Cox and Patrick, 1979(b)
(2.3 ± 0.6)×10 -31 (T/300) -4.6 [N 2 ]229–362Sander and Peterson, 1984(c)
1.5×10 -31 [N 2 ]298Kurylo and Ouellette, 1986(d)
1.8×10 -31 (T/300) -3.2±0.4 [N 2 ]228–358Kurylo and Ouellette, 1987(d)

Comments

(a) Discharge flow system study with laser magnetic resonance detection of HO 2 . The pressure range was 0.7–4 mbar (0.5–3 Torr). The linear plot of k 0 as a function of [M] with a non-zero intercept was interpreted as contribution from the reaction HO 2 + NO 2 HONO + O 2 . As this reaction channel is not present (see comments on preferred values), the non-zero intercept has to be attributed to a curved falloff plot.

(b) Molecular modulation UV spectrometry. HO 2 radicals were generated by Cl 2 photolysis in the presence of H 2 and O 2 . O 2 -N 2 mixtures used in the pressure range 53–800 mbar (40–600 Torr).

(c) Flash photolysis-UV absorption study in the pressure range 67–930 mbar (50–700 Torr). A strong enhancement of reaction in the presence of water vapor was observed, suggested to be due to formation of HO 2 -H 2 O complexes.

(d) Flash photolysis of Cl 2 -CH 3 OH-NO 2 mixtures in the presence of O 2 or N 2 , with HO 2 detection at 225 nm. The falloff curve measured over the pressure range 33–800 mbar (25–600 Torr). The rate coefficient was evaluated using F c = 0.6 and k = 4.7 x 10 -12 (T/300) -1.4±1.0 cm 3 molecule -1 s -1 .

Preferred Values

k0cm3molecule-1s-1{1.8-31 N_2[N2] 1.8×10-31±0.10 N_2[N2]   if   T 298 1.8-31 T 300 PlusMinus -3.2 1 N_2[N2]1.8×10-31 (T/ 300 )( -3.2 ±1) N_2[N2]  if   220 T 360

Comments on Preferred Values

The studies of Howard (1977), Cox and Patrick (1979), Sander and Peterson (1984) and Kurylo and Ouellette (1986, 1987) are in reasonable agreement. The preferred values are based on the study of Kurylo and Ouellette (1987), with the rate coefficient k 0 being evaluated with the value for k given below and F c = 0.6. Modification of F c will lead to minor changes in k 0 and k . Unsuccessful search for HONO as a reaction product in Dransfield et al. (2001) indicates that the reaction HO 2 + NO 2 HONO + O 2 (at a pressure of 120 Torr [160 mbar]) does not occur.

Rate Coefficient Data: High-pressure rate coefficients

Absolute Rate Coefficients

Rate Coefficient (k) / Temperature / ReferenceTechniques and Comments
cm3molecule-1s-1Kelvin
>1.7×10 -12 283Graham et al., 1977, 1978(a)
>(1.5 ± 0.5)×10 -12 283Cox and Patrick, 1979(b)
(4.2 ± 1.0)×10 -12 (T/300) 0.2±1.0 229–362Sander and Peterson, 1984(c)
5.5×10 -12 298Kurylo and Ouellette, 1986(d)
4.7×10 -12 (T/300) -1.4±1.0 228–358Kurylo and Ouellette, 1987(d)

Comments

(a) From thermal decomposition of HO 2 NO 2 in a static reactor with FTIR spectroscopic analysis of HO 2 NO 2 . Measurements at 1 bar of N 2 converted to recombination rate coefficients with the equilibrium constants given in Uselman et al. (1978).

(b) See comment (b) for k 0 . Determination of k by extrapolation of a curved Lindemann-Hinshelwood plot gave an internally consistent falloff plot. The measured value was k = 9.2×10 -13 cm 3 molecule -1 s -1 at 800 mbar (600 Torr) of a 1:1 mixture of N 2 and O 2 .

(c) See comment (c) for k 0 .

(d) See comment (d) for k 0 .

Preferred Values

kcm3molecule-1s-1{4.7-124.7×10-12±0.2  if   T 298 T30004.7×10-12(T/300)0exp  if   220 T 360

Comments on Preferred Values

The preferred values are based on the measurements from Sander and Peterson (1984) and Kurylo and Ouellette (1986) and the falloff analysis of Kurylo and Ouellette (1987). The k 0 and k values are based on F c = 0.6. Modification of the standard value of F c will lead to minor changes in k 0 and k . As long as a temperature independent F c = 0.6 is used and experimental uncertainties in the temperature coefficients of k remain large, we prefer a temperature independent value of k .

References

  • Cox, R. A. and Patrick, K. , Int. J. Chem. Kinet. , 11 , 635 , 1979.
  • Dransfield, T. J., Donahue, N. M. and Anderson, J. G. , J. Phys. Chem. A , 105 , 1507 , 2001.
  • Graham, R. A., Winer, A. M. and Pitts Jr., J. N. , Chem. Phys. Lett. , 51 , 215 , 1977.
  • Graham, R. A., Winer, A. M. and Pitts Jr., J. N. , J. Chem. Phys. , 68 , 4505 , 1978.
  • Howard, C. J. , J. Chem. Phys. , 67 , 5258 , 1977.
  • Kurylo, M. J. and Ouellette, P. A. , J. Phys. Chem. , 90 , 441 , 1986.
  • Kurylo, M. J. and Ouellette, P. A. , J. Phys. Chem. , 91 , 3365 , 1987.
  • Sander, S. P. and Peterson, M. E. , J. Phys. Chem. , 88 , 1566 , 1984.
  • Uselman, W. M., Levine, S. Z., Chan, W. H., Calvert, J. G. and Shaw, J. H. , Chem. Phys. Lett. , 58 , 437 , 1978.