Temperature Effects and Transition State Theory

The effect of temperature on reaction kinetics was an important aspect of experimental studies dating from the earliest work. The common observation is that the rate constant for the reaction increases with increase in temperature. This was considered on a quantitative basis by Arrhenius, who derived the following empirical expression  

Transition state theory was also developed as a means of rationalizing rate constants for gas phase reactions and their temperature dependence. It is most directly applied to bimolecular reactions and is based on three fundamental postulates for reactions in solution  

The chemical species which exists at the transition state is in equilibrium with the reactant state. 

The rate of reaction is equal to the product of the concentration of and frequency with which it decomposes to the product state. 

On the basis of these postulates, a bimolecular reaction may be described as 

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