| Autor: |
Wang, J. J., Keyser, L. F. |
| Zdroj: |
The Journal of Physical Chemistry - Part A; November 2001, Vol. 105 Issue: 46 p10544-10552, 9p |
| Abstrakt: |
The total absolute rate constant (k1a + k1b) for the reactions OH + ClO → Cl + HO2 (k1a) → HCl + O2 (k1b) has been determined in the temperature range from 218 to 298 K at a total pressure of 1 Torr of helium. Pseudo-first-order conditions were used with ClO in large excess over initial OH. ClO was produced by reacting Cl atoms with an excess of O3; both ClO and O3 were quantitatively determined by UV spectrophotometry between 210 and 310 nm. Two sources of OH were used: the reaction of F atoms with excess water vapor and the reaction of H atoms with an excess of NO2. OH was monitored by resonance fluorescence near 308 nm. The absolute rate constant was determined from plots of ln [OH] vs time and absolute ClO concentrations. At 298 K, the result is (2.22 ± 0.33) × 10-11 cm3 molecule-1 s-1. The temperature dependence expressed in Arrhenius form is (7.2 ± 2.2) × 10-12 exp[(333 ± 70)/T] cm3 molecule-1 s-1. The uncertainties are at the 95% confidence limits and include statistical errors from the data analysis and estimates of systematic experimental errors. Numerical simulations show that under the experimental conditions used secondary reactions did not interfere with the measurements. Numerical simulations and experimental checks also show negligible loss of ClO between the time when it is determined by UV absorption and the start of the OH + ClO reaction. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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