Kinetics of the Cl--H2 system. I. Detailed balance in the Cl+H2 reaction

A well-known problem in chemical kinetics is the observation that the ratio of the measured rate constants for the reactions Cl+H2 and H+HCl apparently does not equal the known equilibrium constant. Previous work has indicated that the difficulty exists in the H+HCl measurements, which were complicated by wall effects and secondary reactions of H. We have measured both rate constants over the temperature range 200--500 K, using a resonance fluorescence--flash photolysis apparatus in which wall effects were insignificant. The ratio of our measured rate constants is in excellent agreement with detailed balance