Shock Waves in Chemical Kinetics. Rate of Dissociation of Molecular Bromine

Abstract

The rate of dissociation of molecular bromine in argon-bromine mixtures has been measured in a shock tube and the rate constants for the reaction Br+Br+M→ lim kRBr2+M, in the temperature range 1400°—2700°K, computed. The data are not sufficiently accurate to reveal the temperature coefficient of kR. However, comparison of the average high temperature result, kR=3.4×108 liter2 mole—2 sec—1 at 1600°K, with the room temperature flash lamp result, kR=2.5×109, shows clearly that dkR/dT is negative. Experiments were performed with bromine: argon ratios of 0.01 to 0.10; the efficiency of Br2 as M, the third body for the recombination of bromine atoms, is not greater than 8 times that of argon. The agreement of the results of this investigation with those of an independent shock tube investigation by Palmer and Hornig is gratifyingly good. The extinction coefficients of bromine at 436 mμ and 487 mμ were measured as a function of temperature.