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A B C D E F G H I J K L M N O P Q R S T U V W Z All terms

Arrhenius law

The rate coefficient for a chemical reaction (k) increases exponentially with increasing temperature (T). This relationship is represented by the Arrhenius equation:


Constant Ea in the exponential part of the Arrhenius rate equation (also known as Arrhenius law or Arrhenius equation) associated with the minimum energy difference between the reactants and an activated complex, (transition state which has a structure intermediate to those of the reactants and the products) or with the minimum collision energy between molecules that is required to enable a reaction.

Constant A (also denoted as Z, k*, ko or k? ) is the pre-exponential factor (also known as the frequency factor). The pre-exponential factor is associated with the frequency of collisions between molecules (entropy) and with the probability that these collisions result in a reaction.


  • HarsNet,  HarsBook, A technical guide for the assessment of highly reactive chemical systems, DECHEMA e.V., Frankfurt, 2002.

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