Reactions of chlorine oxide radicals. Part 2.—Kinetics of reaction of atomic oxygen with chlorine

Abstract

The reaction of oxygen atoms (in the absence of molecular oxygen) with chlorine has been studied in a discharge flow system between 1 and 2 mm Hg total pressure and between 174 and 396°K. The rate of reaction of O was first order with respect to both [O] and [Cl₂], and no dependence of the second-order rate constant k₁ upon total pressure, or upon the nature of the surface of the tube, was detected. The mechanism of reaction can be represented by O+Cl₂→ClO+Cl (1) ClO+O→Cl+O₂(2) with k₂≫k₁. The value for k₁ fitted either of the expressions k₁=(5.8±1.5)× 10¹² exp [(–3100±100)/RT] or (2.3±0.7)× 10¹¹T^½ exp [(–2900±100)/RT] cm³ mole^–1 sec^–1 in the range 174–396°K. The magnitude of the activation energy is consistent with an approximate correlation of activation energy with heat of reaction for related transfer reactions of an oxygen atom with a diatomic molecule.