The thermal decomposition of water

✍ Scribed by N. K. Srinivasan; J. V. Michael

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 164 KB
• Volume: 38
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.20172

✦ Synopsis

Abstract

The reflected shock tube technique with multipass absorption spectrometric detection of OH‐radicals at 308 nm, corresponding to a total path length of 1.749 m, has been used to study the reaction H~2~O + M → H + OH + M between 2196 and 2792 K using 0.3, 0.5, and 1% H~2~O, diluted in Kr. As a result of the increased sensitivity for OH‐radical detection, the existing database for this reaction could be extended downward by ∼500 K. Combining the present work with that of Homer and Hurle, the composite rate expression for water dissociation in either Ar or Kr bath gas is k~1,Ar(or Kr)~ = (2.43 ± 0.57) × 10^−10^ exp(−47117  ± 633 K/T) cm^3^ molecule^−1^ s^−1^ over the T‐range of 2196–3290 K. Applying the Troe factorization method to data for both forward and reverse reactions, the rate behavior could be expressed to within <±18% over the T‐range, 300–3400 K, by the three‐parameter expression k~1,Ar~ = 1.007 × 10^4^ T^−3.322^ exp(−60782 K/T) cm^3^ molecule^−1^ s^−1^ A large enhancement due to H~2~O with H~2~O collisional activation has been noted previously, and both absolute and relative data have been considered allowing us to suggest k~1~, H~2~ O = 1.671 × 10^2^ T^−2.440^ exp(−60475 K/T) cm^3^ molecule^−1^ s^−1^ for the rate constants with H~2~O bath gas over the T‐range, 300–3400 K. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 211–219, 2006