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Activation energy, the activated complex, and the effect of a catalyst
ENTHALPY Activation energy, the activated complex, and the effect of a catalyst
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Learning Objectives The activated complex is an unstable arrangement of atoms formed at the maximum of the potential energy barrier, during a reaction. The activation energy is the energy required by colliding molecules to form an activated complex. The activation energy can be calculated from potential energy diagrams. The effect of a catalyst can be explained in terms of alternative reaction pathways with lower activation energy. A potential energy diagram can be used to show the effect of a catalyst on activation energy.
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ACTIVATION ENERGY
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Energy Reactants Products Reaction Progress
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Energy EA Reactants DH Products Reaction Progress
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Energy Reactants DH Products Reaction Progress
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Energy Reactants DH Products Reaction Progress
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Energy EA Reactants DH Products Reaction Progress
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What happens here? Energy EA Reactants DH Products Reaction Progress
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THE ACTIVATED COMPLEX
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Reactant A
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Reactant A Reactant B
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Activated complex
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Activated complex
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Activated complex
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Product C Product C
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EA DH Activated Complex Reactants A + B Product C Reaction Progress
Energy EA Reactants A + B DH Product C Reaction Progress
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THE EFFECT OF A CATALYST
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NUMBER OF MOLECUES WITH
A PARTICULAR ENERGY Ea MOLECULAR ENERGY
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NUMBER OF MOLECUES WITH
A PARTICULAR ENERGY EXTRA MOLECULES WITH SUFFICIENT ENERGY TO OVERCOME THE ENERGY BARRIER Ea MOLECULAR ENERGY
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Effect of catalyst Without catalyst EA DH Reactants Products
Energy EA Reactants DH Products Reaction Progress
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Effect of catalyst With catalyst DH Reactants Products
Energy With catalyst Reactants DH Products Reaction Progress
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Effect of catalyst EA With catalyst DH Reactants Products
Energy EA With catalyst Reactants DH Products Reaction Progress
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Effect of catalyst Without catalyst EA DH Reactants Products
Energy EA Reactants DH Products Reaction Progress
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Effect of catalyst EA With catalyst DH Reactants Products
Energy EA With catalyst Reactants DH Products Reaction Progress
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Effect of catalyst Without catalyst EA EA With catalyst DH Reactants
Energy EA EA With catalyst Reactants DH Products Reaction Progress
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