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 [H]>[OH]≫[O]>[O2], which are listed in order of decreasing concentrations. The decay of acetylene in this environment at 1700° to 2000°K can be represented by −d[C2H2]/dt=2×1012[OH][C2H2] moles cm−3·sec−1but 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].