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Enthalpy and activation energy

  1. Feb 11, 2015 #1
    1. The problem statement, all variables and given/known data
    This question is just for an overall understanding of enthalpy and activation. My book states that catalysts decrease the activation energy of a reaction. This makes sense. However, how does this change the enthalpy? If a catalyst creates a new pathway, wouldn't the enthalpy change be different as compared to the reaction without a catalyst? Thanks in advance.

    2. Relevant equations
    NA

    3. The attempt at a solution
     
  2. jcsd
  3. Feb 11, 2015 #2

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    It doesn't change the enthalpy of the reaction. It does change the activation enthalpy of the reaction.

    Enthalpy of a reaction is the difference in enthalpies only between the initial and final states. Activation energy or activation enthalpy is the maximum energy change on the path the reaction takes between those initial and final states.
     
  4. Feb 11, 2015 #3
    Oh I get it but let me be clear. Initial and final states (as defined by state functions) will be the same regardless if the reaction uses a catalyst. Thus Ea is lower but the ΔH for both will be the same?
     
  5. Feb 11, 2015 #4

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    You are cooking.
     
  6. Feb 11, 2015 #5
    Thank you!
     
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