Kinetics of reactions involving CN emission. II. The reaction between oxygen atoms and cyanogen

Abstract

The reaction between oxygen atoms and cyanogen has been studied in a flow system at temperatures up to 400 °C in the pressure range 1.0 to 5.0 mmHg. This reaction is first order in both reactants, and has an activation energy of 11.0 ± 2.0 kcal/mole; this is associated with the initial attack of an oxygen atom on cyanogen for which the exponential factor is close to 4 x 10 13 cm 3 mole -1 s -1 . It has not been possible to choose between mechanisms in which the initial steps are O + C 2 N 2 = NCO + CN (6) and O + NCO = NO + CO, (7) or O + C 2 N 2 = NCN + CO (8) and O + NCN = NO + CN. (9) Subsequent reactions include CN + NO = CO + N 2 , (11) O + CN = N + CO. (12) In the presence of molecular oxygen reactions (10) and (7) become important CN + O 2 = NCO + O. (10) Strong CN emission accompanying the reaction is shown to be largely due to the reaction O+O+CN = O 2 + CN*. (20) Quenching of this emission by various additives is associated with their reaction with CN for which relative rate constants are deduced.