Some Comparisons of the Classical RRK and the RRKM Theoretical Rate Formulations

It is shown by comparison with RRKM (Rice—Ramsperger—Kassel—Marcus) calculations for unimolecular reactions that the classical Kassel empirical fit parameter s is a complex function of temperature, the critical energy ε0, and of the vibrational pattern of the molecule and activated complex considered. The comparisons have afforded a delineation of quantal molecular behavior and of the empirical classical interpretation. Some detailed application is made to the methane and fluoroform decomposition reactions. Possible discrepancies in shock-tube measurements are discussed.