Consistency of theory and experiment in the ethane–methyl radical system

The thermal decomposition of ethane has been reinvestigated using the single pulse, reflected shock technique. Reflected shock temperatures were corrected for boundary layer‐induced nonidealities using the thermal decomposition of cyclohexene as a kinetic standard. The rate constant for the reaction equation image was calculated from the rate of formation of methane under conditions of very low extent of reaction, over a temperature range of 1000–1241 K. Ethane compositions of 1% and 3% in argon at total reaction pressures of 3 and 9 atm were used, and a small pressure dependence of k1 was observed. An RRKM model is described which gives excellent agreement with this and other recent dissociation and recombination rate constant data in light of a recent revision to the thermochemistry of the methyl radical. In the range of 1000–1300 K an RRKM extrapolated k is given by the expression, log k = 17.2 − 91,000/2.3RT, while at 298 K the calculation gives log k (l/mol sec) = 10.44, where k is calculated from k and the equilibrium constant.