Definition

Arrhenius' law is a law that describes the kinetics of a chemical reaction as a function of temperature. It was enunciated by Svante August Arrhenius in 1889. However, this law is an empirical law even though it has been verified experimentally on numerous occasions.

Statement

  • k, being the speed coefficient

  • T, the temperature in degrees Kelvin (K)

  • R, the perfect universal gas constant (i.e. 8,314 J.mol-1.K-1).

  • Ea, the activation energy in joules per mole (J.mol-1)

This law can be simplified as follows when the activation energy is not dependent on temperature.

Interpretation

This law makes it possible to conclude the following points:

  • The higher the temperature, the greater the kinetics of a reaction. This evolves even exponentially, generally speaking, an increase of 10 K (or 10°C, it is equivalent in this case), can multiply the kinetics of the reaction by 2 or 3.

  • The lower the activation energy of a chemical reaction, the faster the kinetics of the reaction.

  • At absolute 0, the kinetics of the reaction is zero and it does not occur.

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