Kinetic study of the Br+IO, I+BrO and Br+I-2 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 + I-2 --> I + IBr (4) have been measured at 298 K and 1 Torr: k(2) = (2.3 +/- 0.3) x 10(-11), k(3) = (1.45 +/- 0.20) X 10(-11) and k(4) = (1.20 +/- 0.15) X 10(-10) cm(3) 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): Delta H-f,H-298(BrO) = 28.6 +/- 1.4 kcal mol(-1).