Change in Enthaply and Activation Energy

AI Thread Summary
In exothermic reactions, the activation energy for the forward reaction (Ea(fwd)) can indeed be less than the enthalpy change (ΔrH), which is negative. The confusion arises because while ΔrH is negative, the activation energy must be a positive value. The book's answer likely refers to the magnitudes of these values rather than their direct comparison. Understanding this distinction clarifies the relationship between activation energy and enthalpy change in exothermic reactions. This highlights the importance of considering the signs and magnitudes when analyzing reaction energetics.
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Homework Statement



For a reaction that is exothermic in the forward direction, can the activation energy Ea(fwd) ever be less than the enthalpy change?

Homework Equations



Endothermic equation: Ea(rev) = Ea(fwd) - deltarH

The Attempt at a Solution


[/B]
The answer in the book has "yes", but I don't know how this can be true.

Since it's an exothermic reaction, deltarH is negative. And as far as I know, the forward activation energy must be positive. Is it possible that the book meant magnitude? If so, then I could understand why they gave that answer.
 
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student34 said:
Is it possible that the book meant magnitude?

That would be my understanding.
 
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Borek said:
That would be my understanding.
:smile: Thanks!
 
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