Rate of Destruction of Acetylene in Flame Gases

The burnt gas from fuel‐rich acetylene—oxygen flames contains larger than equilibrium amounts of acetylene, but only equilibrium amounts of the species $[\mathrm{H}\mathrm{]>[}\mathrm{OH}\mathrm{]\gg [}\mathrm{O}\mathrm{]>[}{\mathrm{O}}_2]$ , which are listed in order of decreasing concentrations. The decay of acetylene in this environment at 1700° to 2000°K can be represented by $$\mathrm{-d[}{\mathrm{C}}_2{\mathrm{H}}_2{\text{]/dt=2×10}}^{12}[\mathrm{OH}\mathrm{][}{\mathrm{C}}_2{\mathrm{H}}_2\mathrm{]\hspace{0.17em}}{\mathrm{moles\; cm}}^{\text{−3}}·{\sec }^{\text{−1}}$$ but cannot be represented by k[X][C₂H₂] where [X] is [H], [O], or [O₂]. Therefore acetylene may be consumed at the rate of its irreversible reaction with OH; and if so, it reacts five to 10 times slower with OH than with an equal concentration of O in flames, the latter rate having been estimated previously in an environment where [O]>[OH].