Shock Tube Determination of Dissociation Rates of Oxygen

Abstract

The rate of dissociation of oxygen in Xe–O₂ mixtures was measured over a temperature range of 3000°K to 6000°K. An x‐ray densitometer was used to measure the density during the dissociation process behind a shock wave. It was possible to match the experimental data with theoretical density profiles over a wide range of compositions and initial conditions. The reactions considered were $${\mathrm{O}}_2\mathrm{+M\rightleftharpoons }{\displaystyle {lim}_{k_r}^{k_d}}\text{2\hspace{0.17em}}\mathrm{O}\mathrm{+M,}$$ where M can be Xe, O₂, or O. Considering these species as third bodies, the deduced recombination rates in cc² mole^—2 sec^—1 were 4.7×10¹⁷ T^—1, 1.6×10¹⁸ T^—1, and 4.8×10¹⁸ T^—1, respectively. The third‐body efficiencies of O₂ and O relative to Xe are 3 and 10. Experimental conditions were such that an accurate measurement of the exponent of the temperature could not be made. However, since the data showed it to be within the limits of —½ and —2, a value of —1.0 was arbitrarily chosen. The agreement between results reported here and previous work demonstrates the potential utility of this method for kinetic studies of other reactions.