Rate coefficient for H + O2 + M = HO2 + M evaluated from shock tube measurements of induction times

Abstract Hydrogen-air induction times near to the second explosion limit have been measured in a shock tube. By matching these experimental results with numerically predicted induction times, the rate coefficient for the reaction H + O 2 + M = HO 2 + M, was evaluated as k 4,N 2 = 3.3(±.6) × 10 15 cm 6 mole −2 sec −1 in the temperature range 980 to 1176 °K. A similar analysis of hydrogenoxygenargon induction time data, obtained by Skinner and Ringrose, yielded k 4,Ar = 2.2 (±.4) × 10 15 cm 6 mole −2 sec −1 over the temperature range 964 to 1075 °K. The sensitivity of induction times to the rate coefficients of other reactions in the H 2 O 2 system was examined. The present values of k 4 agreed well with previous high-temperature shock tube data and, based on a critical evaluation, k 4,Ar = 2.1 × 10 18 · T −1 cm 6 mole −2 sec −1 , is recommended as giving the best fit to experimental data between 200 and 2200 °K. Data on the efficiency of nitrogen relative to argon as the chaperon molecule exhibits a systematic temperature dependence, decreasing from about 3.1 at 300 °K to 1.5 above 1000 °K.