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Temperature‐dependent a factor in thermal unimolecular reactions II. Exponential dependence
Author(s) -
Forst Wendell,
Turrell Sylvia
Publication year - 1981
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550130307
Subject(s) - chemistry , thermodynamics , exponential function , power law , butane , limiting , constant (computer programming) , reaction rate constant , kinetics , physics , classical mechanics , organic chemistry , mathematical analysis , mechanical engineering , statistics , mathematics , computer science , engineering , programming language , catalysis
It is assumed that A ∞ in the limiting high‐pressure unimolecular rate constant expression k ∞ = A ∞ exp(− E a ∞ / kT ) is given by A ∞ = A ″ ∞ e BkT . The test case is the decomposition butane → 2 ethyl, where a negative B reproduces the temperature dependence of A ∞ about as well as the previously considered power law A ∞ = A ′ ∞ ( kT ) n . It is shown that the term e BkT modifies significantly the high‐temperature falloff of the general‐pressure rate constant k uni and its various derivatives, and admits of a fairly simple interpretation in terms of Benson's restricted rotor theory. On physical grounds, the exponential law appears more reasonable than the power law.