Reaction between nitrate radical and formaldehyde in air: a determination of the rate constant at 295 .+-. 2 K
| Autor: | J. Hjorth, G. Restelli, G. Ottobrini |
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| Rok vydání: | 1988 |
| Předmět: | |
| Zdroj: | The Journal of Physical Chemistry. 92:2669-2672 |
| ISSN: | 1541-5740 0022-3654 |
| DOI: | 10.1021/j100320a053 |
| Popis: | The reaction between NO/sub 3/ and CH/sub 2/O was studied in a 450-L glass/Teflon chamber by using FT-IR spectroscopy as the analytical technique. NO/sub 3/ was obtained in equilibrium with N/sub 2/O/sub 5/ introduced from evaporation of the solid phase into the cell or generated in the cell itself by reacting NO/sub 2/ with O/sub 3/. Experiments were performed in both cases at 295 +/- 2 K and 740 Torr in purified air. /sup 13/CH/sub 2/O was used to avoid spurious effects on the measured CO; /sup 13/C/sup 18/O was introduced to estimate the OH radical concentration in the system from the buildup of the oxidation product /sup 16/O/sup 13/C/sup 18/O. /sup 13/CH/sub 2/O, /sup 13/C/sup 16/O, N/sub 2/O/sub 5/, O/sub 3/, NO/sub 2/, and H/sup 13/COOH time-dependent concentrations were measured and the data fitted on the basis of a model involving 31 reactions, with the aid of the FACSIMILE computer program. A rate constant for the reaction NO/sub 3/ + CH/sub 2/O equal to (5.4 +/- 1.1) x 10/sup -16/ cm/sup 3/ molecule/sup -1/ s/sup -1/, at 295 +/- 2 K and 740 Torr, has been obtained assuming for the reactions N/sub 2/O/sub 5/ in equilibrium /sup +M/ NO/submore » 3/ + NO/sub 2/ an equilibrium constant equal to 5.3 x 10/sup 19/ molecules cm/sup -3/. Significant differences have been found between the measured concentrations of OH and HCOOH with respect to those predicted by the model. In the framework of this study, the absolute strength of the v/sub 6/ band of H/sup 12/COOH (1045-1150 cm/sup -1/) has been measured equal to (3.48 +/- 0.5) x 10/sup -17/ cm molecule/sup -1/.« less |
| Databáze: | OpenAIRE |
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