Also contains definition of: degree of activation
This word is used in different senses:
  1. Input of external energy into a chemical system is said to bring about activation of the system.
  2. An added substance that increases the rate of a catalysed reaction is known as an activator, and the effect is called activation. The degree of activation \(\varepsilon_{\text{a}}\) is defined by: \[\varepsilon_{\text{a}}=\frac{v\,-\,v_{0}}{v_{0}} = \frac{v}{v_{0}} - 1\] where \(v_{0}\) is the rate of the catalysed reaction in the absence of the activator and \(v\) is the rate of the catalysed reaction in the presence of the activator.
  3. When some of the energy required for a reaction to occur is provided by a previous exothermic chemical reaction there is said to be chemical activation.
See: catalysis, chemical activation
See also: activator, inhibition
PAC, 1996, 68, 149. 'A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)' on page 151 (