A kinetics study of the reaction of OH radicals with two C2 hydrocarbons: C2H4 and C2H2

Abstract

The flash photolysis-resonance fluorescence technique has been utilized to study the kinetics of hydroxyl radical reactions with ethylene and acetylene at 300 K over a wide range of experimental conditions. (1) OH+C2H4 →k1 Products (e.g., C2H5O), (2) OH+C2H2 →k1 Products (e.g.,C2H2O+H). The bimolecular rate constant for Reaction (1) was observed to increase from (2.24–5.33) × 10−12 cm3 molecule−1⋅ sec−1 as the total pressure varied from (3–300) torr of helium. The rate of Reaction (2) was invarient with total pressure, and the value obtained for k2 was (1.65±0.15) × 10−13 cm2 molecule⋅sec−1. The observed pressure dependency of Reaction (1) brings the existing literature values for k1 into close agreement. Reaction (2) has been shown to be particularly sensitive to secondary processes and this is discussed in some detail.