Reaction Coordinate Diagrams
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A reaction coordinate diagram (or energy diagram) illustrates the changes in energy taking place over the course of a chemical reaction. The total energy of reactants and products are plotted against the progress of the reaction. An example is shown below.
You need to be familiar with the features of the plot. Reactants will always appear on the left and progress to products shown on the right. Each step of the reaction will have a transition state ("bump" on the curve). A transition state is when bond breaking and/or bond making occur. The "valleys" between transition states are known as intermediates. Intermediates are high-energy species that are not able to be isolated and only exist for a very brief time during the reaction.
An energy diagram is related to the reaction mechanism. If the mechanism has two steps, this means that there will be two transition states. The mechanism below corresponds to the diagram shown above.
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Head back to canvas to practice identifying the different parts of a reaction coordinate diagram!
For more information, please read page 157 and section 5.9 in the textbook.