Activation Energy and the Temperature Dependence of Rates

Under certain conditions, the bromination of cyclohexene follows an interesting rate law  

When a small piece of platinum is added to a mixture of ethene and hydrogen, the following 

Doubling the concentration of hydrogen has no effect on the reaction rate. Doubling the concentration of ethene also has no effect. 

Each reaction has its own characteristic rate constant, k. Its value depends on the conditions of the reaction, especially the temperature. This temperature dependence is expressed by the Arrhenius equation, 

The activation energy, E, is the minimum kinetic energy the molecules must have to overcome the repulsions between their electron clouds when they collide. The exponential term corresponds to the fraction of collisions in which the particles 

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