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Reaction coordinate diagrams

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Reaction coordinate diagrams Collision Theory states that the particles must collide with enough energy and the proper orientation Figure 14.12 Importance of ... – PowerPoint PPT presentation

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Title: Reaction coordinate diagrams


1
Reaction coordinate diagrams
2
Collision Theory states that the particles must
collide with enough energy and the proper
orientation
3
Transition State Theory
  • Explains that if reactants collide with enough
    energy and the proper orientation, an activated
    complex will form.
  • An activated complex is high energy, unstable
    intermediate particle.
  • The activated complex can break apart to form
    reactants again or it can form products.

4
Activation Energy
  • There is a minimum amount of energy required for
    reaction to occur the activation energy, Ea.
  • Just as a ball cannot get over a hill if it does
    not roll up the hill with enough energy, a
    reaction cannot occur unless the molecules
    possess sufficient energy to get over the
    activation energy barrier.

5
Reaction Coordinate Diagrams
  • It is helpful to visualize energy changes
    throughout a process on a reaction coordinate
    diagram like this one.

6
Reaction Coordinate Diagrams
  • It shows the energy of the reactants and products
    (and, therefore, ?E).
  • The high point on the diagram is the transition
    state.
  • The species present at the transition state is
    called the activated complex.
  • The energy gap between the potential energy of
    reactants and the activated complex is the
    activation energy.

7
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8
Exothermic reaction
  • Draw a reaction coordinate diagram in your
    notebook.
  • Label it

9
Endothermic Reaction
  • Draw the reaction coordinate diagram for an
    endothermic reaction and label it.
  • The reaction coordinate diagram of an endothermic
    reaction will start with low energy reactants and
    end with higher energy products.

10
Catalysts
  • Catalysts increase the rate of a reaction by
    decreasing the activation energy of the reaction.
  • Catalysts change the mechanism by which the
    process occurs.

11
Catalysts
  • One way a catalyst can speed up a reaction is by
    holding the reactants together and helping bonds
    to break.

12
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13
Enzymes
  • Enzymes are catalysts in biological systems.
  • The substrate fits into the active site of the
    enzyme much like a key fits into a lock.
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