The Decomposition of Ethyl Bromide and the Collision Theory of First-Order Reactions

Abstract

The reaction C₂H₅Br→C₂H₄+HBr has been studied in the neighborhood of 400° with special reference to the effect of the wall surface and the addition of bromine. Earlier experimental facts are summarized and shown to be in agreement with the hypothesis that the primary step is the production of C₂H₅ and Br, followed by chemical reactions which do not involve a long chain. The low pressure effects are explained on the basis of wall effects. The decrease in the value of the first‐order rate constant at low pressures can be explained in this reaction and in the decomposition of nitrogen pentoxide without the aid of the collision theory. It is suggested that other examples which have been regarded as confirmations of the collision theory may find similar explanations. It may be necessary to revise the quantitative aspects of the collision theory to allow for a decrease in k at lower pressures than have been heretofore considered.