How is internal energy change different from the heat of reaction?

[thebillsfan]

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See thread title..under what conditions is internal energy change NOT the same thing as heat of reaction?

 

[RogueUnicorn]

when the process is not adiabatic.

 

[G1SG2]

when the process is not adiabatic.

The process can be adiabatic or not adiabatic-I don't think that matters because we can either have E=w or E=q+w (either way, we won't have E=q). It depends on the work. If there's constant volume, no PV work is done, and so E=q. So, internal energy is different from the heat of the reaction when PV WORK IS DONE, because then E=q + w.

 

[RogueUnicorn]

The process can be adiabatic or not adiabatic-I don't think that matters because we can either have E=w or E=q+w (either way, we won't have E=q). It depends on the work. If there's constant volume, no PV work is done, and so E=q. So, internal energy is different from the heat of the reaction when PV WORK IS DONE, because then E=q + w.

no. work done in an adiabatic process will decrease the temperature and thus the internal energy of a gas. the energy doesn't spontaneously arise.