Kinetics and mechanism of the reaction of Cl atoms with HO2 radicals

The kinetics and mechanism of the reaction Cl + HO2 --> products (1) have b een studied in the temperature range 230-360 K and at total pressure of 1 T orr of helium using the discharge-flow mass spectrometric method. The follo wing Arrhenius expression for the total rate constant was obtained either f rom the kinetics of HO2 consumption in excess of Cl atoms or From the kinet ics of Cl in excess of HO2: k(1) = (3.8 +/- 1.2) x 10(-11) exp{(40 +/- 90)/ Tl cm(3) molecule(-1) s(-1), where uncertainties are 95% confidence limits. The temperature-independent value of k(1) = (4.4 +/- 0.6) x 10(-11) cm(3) molecule(-1) s(-1) at T = 230-360 K, which can be recommended from this stu dy. agrees well with most recent studies and current recommendations. Both OH and ClO were detected as the products of reaction (1) and the rate const ant For the channel forming these species, Cl + H2O --> OH + ClO (Ib), has been determined: k(1b) = (8.6 +/- 3.2) x 10(-11) exp\ -(660 +/- 100)/T\ cm( 3) molecule(-1) s(-1) (with k(1b) = (9.4 +/- 1.9) x 10(-12) cm(3) molecule( -1) s(-1) at T = 298 K), where uncertainties represent 95% confidence limit s. (C) 2001 John Wiley & Sons. Inc.