Energy Level Diagrams

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Energy Level Diagrams

In Exothermic Reactions...

  • /\H is negative
  • The products are at a lower energy than                                                                           the reactants.
  • The height difference represents the                                                                            energy given out per mole.
  • The initial rise represents the energy                                                                          needed to break the old bonds. 

In Endothermic Reactions...

  • /\H is positive
  • The products are at a higher temperture                                                                          than the reactants.
  • The difference in height represents the                                                                          energy taken in during the reaction.
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Activation Energy

What is Activation Energy?

  • It is the initial energy given out that is used to break the bonds of the reactants.
  • It represents the minimum energy needed for the reaction to happen.
  • It is only shown on the energy diagrams for exothermic reactions.

Activation Energy and Cataysts:

  • Catalysts lower the activation energy                                                                        because it provides an alternative                                                                            reaction pathway.
  • This is shown by the lower curve on                                                                                 the graph because less initial energy                                                                                  is needed for the reaction to happen.
  • The overall enthalpy change remains                                                                                the same even with a catalyst.
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