Formation and decomposition of chemically activated ethyl radicals is simulated by the Monte Carlo quasiclassical trajectory method. The results are compared with a previous study of a microcanonical ensemble of ethyl radicals. Chemically activated ethyl radicals have an apparent non-RRKM lifetime distribution as a result of nonrandom excitation. However, rapid intramolecular relaxation processes give a lifetime distribution after approximately 5 × 10-12 s which agrees with that for a microcanonical ensemble. A statistical model for partitioning of energy and angular momenta at the dissociation barrier is given, and the trajectory results agree with the predictions of the model.