KINETIC STUDIES OF HYDROXYL RADICALS IN SHOCK WAVES. I. THE DECOMPOSITION OF WATER BETWEEN 2400 AND 3200 K

Journal Article · Sun Jun 01 00:00:00 EDT 1958 · Journal of Chemical Physics (U.S.)

DOI:https://doi.org/10.1063/1.1744349· OSTI ID:4329426

Bauer, S H; Schott, G L; Duff, R E

The decomposition of water vapor has been studied at temperatures between 2400 and 3200M generated in plane shock waves by following changes in the concentration of OH with time. Specific radiation absorbimetry permits these measurements to be made with microsecond resolution. The source of OH radiation used was a flash lamp containing water vapor. Measurements were made on the gas behind reflected shock waves in argon at initial pressures near 50 mm Hg and containing the reactant. H/sub 2/O vapor, in amounts of the order of 1 mole %. The shock tube and associated electronic and optical equipment are described. Problems of purity, chemical analysis, and reduction of data are discussed. Absorption by OH was calibrated with the equilibrium mixtures resulting from the decomposition of H/sub 2/O and from the reaction of H/sub 2/ and O/sub 2/. The rate of formation of OH from H/sub 2/O is proportional to the H/sub 2/O concentration and nearly independent of the argon pressure. The effective activation energy is about 50 kcal/mole. Addition of 2% O/sub 2/ to the mixture approximately doubles the rate of OH formation and preserves the 50 kcal activation energy. Addition of 2% H/sub 2/ decreases the rate and increases the activation energy to about 80 kcal/mole. Possible reaction mechanisms are considered. The initial rate of appearance of OH cannot be interpret d in terms of the simple dissociation of H/sub 2/O into H and H, and it seems necessary to consider a relatively lo energy path involving H/sub 2/O/sub 2/ or the H/sub 2/O/ sub 2/ radical as an intermediate. (auth)

• Research Organization: Cornell Univ., Ithaca, N.Y.; Los Alamos Scientific Lab., N. Mex.
• Sponsoring Organization: USDOE
• NSA Number: NSA-12-012236
• OSTI ID: 4329426
• Journal Information: Journal of Chemical Physics (U.S.), Journal Name: Journal of Chemical Physics (U.S.) Vol. Vol: 28; ISSN JCPSA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ABSORPTION-- ARGON-- DECOMPOSITION-- ELECTRONIC EQUIPMENT-- FREE RADICALS-- GASES-- HIGH TEMPERATURE-- HYDROXIDES-- MEASURED VALUES-- OPTICAL SYSTEMS-- PRESSURE-- QUANTITY RATIO-- RADIATION DOSES-- RADIATION SOURCES-- REACTION KINETICS-- REFLECTION-- SHOCK WAVES-- VAPORS-- WATER
ACTIVATION-- ENERGY-- ENERGY LEVELS-- HYDROGEN-- IMPURITIES-- MIXING-- OXYGEN-- QUALITATIVE ANALYSIS-- REACTION KINETICS-- THERMODYNAMICS
CHEMISTRY