Reaction Coordinate Diagrams and Mechanisms

Intermediate Organic Chemistry, Third Edition. Ann M. Fabirkiewicz and John C. StoweU. 2016 John Wiley Sons, Inc. Pnblished 2016 by John Wiley Sons, Inc. 

A reaction that requires a higher rise to a transition state (activation energy) will be slower than one requiring a lesser rise (if the probability factors are similar) because a smaller fraction of collisions will provide sufficient potential energy to make it. 

The energy values for such plots are derived from measurements of overall exo- or endothermicity and from measurement of the effect of varying the temperature on the rate of the reaction (Section 4.3.6). 

Since molecules are individually too small and too fast for direct observation, our pictorial mechanisms are not the final word. Published 

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