Term: pre-exponential factor, A
https://doi.org/10.1351/goldbook.P04811

Definition:
coefficient in front of the exponential factor expressing the empirical temperature dependence of the rate coefficient, k, on temperature, T,k = A exp^(-Ea/R.T), where Ea is the activation energy.

Related Terms:
1) coefficient (http://doi.org/10.1351/goldbook.C01124).
2) activation (http://doi.org/10.1351/goldbook.A00093).
3) rate coefficient (http://doi.org/10.1351/goldbook.R05137).

Source: Green Book, 2nd ed., p. 56 (https://goldbook.iupac.org/files/pdf/green_book_2ed.pdf)

Citation: 'pre-exponential factor, A' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.P04811

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