Kinetic Study of the Reaction of Hydrogen Atoms with Molecular Chlorine at MilliTorr Pressures

The bimolecular reaction H + Cl2 → ΗCl + Cl (1) is studied in the very low-pressure reactor (VLPR) system at room temperature. Excellent mass balances are found between the Cl2 consumption and both HCl as well as Cl product formation. This indicates that only reaction 1 occurs in the system. Its rate constant is k 1 = (0.96 ± 0.04) × 10-11 cm3/(molecule·s) at 298 K. Two independent estimates of the A factor give a value log A 1(298 K) = −9.80 ± 0.15 (units of cm3/(molecule·s)). Together with the measured rate constant this yields an activation energy of 1.7 ± 0.2 kcal/mol. All experimental data support a bent transition state for reaction 1.