Gaseous Reaction Rates at High Temperature. I. The Dissociation of Carbon Dioxide

The rate of dissociation of carbon dioxide has been measured in the temperature range 3000°—5000°K. The amount of carbon dioxide was varied from 1% to 10% in a diluent of argon or nitrogen. The concentration of the mixture was varied from 0.11×10⁻⁵ to 0.49×10⁻⁵ mole/cc. It is shown that the decrease in temperature and increase in density caused by the endothermic dissociation must be considered in the analysis of the data. A computer program was employed to account for the effect of the changes in temperature and density on the observed rate of dissociation. The rate constants for the reaction $${\mathrm{CO}}_2+\mathrm{M}\to \mathrm{CO}+\mathrm{O}+\mathrm{M}$$ were determined to be $$k_{\text{1,}\mathrm{Ar}}{\text{=7.11×10}}^{11}{T}^{\frac{1}{2}}\exp \text{(−84\hspace{0.17em}500/RT)\hspace{0.17em}}\mathrm{cc}/\mathrm{mole}·\sec$$ with argon as the diluent and $$k_{\text{1,}{\mathrm{N}}_2}{\text{=5.33×10}}^{11}{T}^{\frac{1}{2}}\exp \text{(−79\hspace{0.17em}600/RT)\hspace{0.17em}}\mathrm{cc}/\mathrm{mole}·\sec$$ with nitrogen as the diluent. The probable dissociation mechanism also is discussed.