The stoichiometry of the reaction of aqueous ozone with sodium azide was studied at pH 12 (mainly) where a yellow metastable intermediate is observed. We propose that this is hypoazidite (N3O−), analogous to hypobromite, and that it plays a central role in the azide catalyzed decompostion of ozone. The yellow intermediate is unstable in acid, in which it rapidly decomposes, generating N2 and NO2−. The rate of reaction was studied at pH 2.0–3.5, with the ionic strength at 0.6 M and temperature at 3–15 ° C. The intrinsic second-order rate constants were found to be k HN3 ≤ ≈ 400 M-1sec-1 and k N3- = (8.7 ± 0.5) × 105 M-1sec-1 (3 °C, 0.6 M), both in agreement with the only other previous study. The rate constant at 25 °C was estimated using the following experimentally determined parameters: ln kN3- (M-1sec-1) = (5.73 ± 0.36) × 103/T (K) + (28.34 ± 1.27). The value of kN3- estimated in this way is (2.5 ± 0.1) × 106 M-1sec-1 at 25 °C and 0.6 M. The enthalpy of reaction (A H) is -48 ± 3 kJ mol-1.
|Original language||English (US)|
|Number of pages||8|
|Journal||Journal of the Air and Waste Management Association|
|State||Published - Nov 1999|
ASJC Scopus subject areas
- Waste Management and Disposal
- Management, Monitoring, Policy and Law