Kinetic study of the Br + IO, I + BrO and Br + I2 reactions. Heat of formation of the BrO radical

Using the discharge-flow mass spectrometric method, the rate coefficients for the reactions Br + IO → I + BrO (2), I + BrO → Br + IO (3) and Br + I2 → I + IBr (4) have been measured at 298 K and 1 Torr: k2 = (2.3 ± 0.3) × 10−11, k3 = (1.45 ± 0.20) × 10−11 and k4 = (1.20 ± 0.15) × 10−10 cm3 molecule−1 s−1. The value of the enthalpy of BrO formation has been derived from the kinetic data obtained for reactions (2) and (3): ΔHf,298(BrO) = 28.6 ± 1.4 kcal mol−1.