The collision theory of gaseous reactions

The science of reaction kinetics between molecular species in a homogeneous gas phase was one of the earliest fields to be developed, and a quantitative calculation of the rates of chemical reactions was considerably advanced by the development of the collision theory of gases. According to this approach the rate at which the classic reaction 

The reaction constant k was related to a collision number Z, the number of reactant molecules colliding/unit time, and an activation energy E by the Arrhenius equation 

The Tempered activation energy , is the activation energy divided by R, the gas constant, and is dimensionless. It will be shown here with a superscript T, e.g. 10000.  

A reaction with an activation energy of lOOkJ will occur at too high a rate to be measurable at 500 K, one with 200 kJ will be measurable in the temperature range around 800 K, with 300 kJ at temperatures around 1000 K, and finally a reaction having an activation energy of 400 kJ or more will become measurable above 1300 K. 

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