The thermal dissociation of ethane. A study of the reaction over an extended pressure range

Abstract

The rates of dissociation of ethane into two methyl radicals have been determined by measuring the rate of formation of methane at 862 K at pressures in the range 0.01–30 Torr. The results coupled with earlier measurements provide rate coefficients for the dissociation reaction over a pressure region where the reaction order varies from ca. 1.9 to 1.1. The data have been fitted to an RRKM model over this range. There are indications of the occurrence at the lower end of the pressure range of a heterogeneous process leading to methane formation, which prevented the extension of the investigation to even lower pressures. Application of the results obtained from this study to a recently proposed expression for rate coefficients of unimolecular reactions in the fall-off region shows that there is good agreement in this case between theory and experiment.