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Posted: Thu Feb 07, 2019 12:38 pm
Is ΔH always equal to qp? Also, under what circumstances does ΔH=ΔU?
Posted: Thu Feb 07, 2019 12:49 pm
Delta H equals qp for a system under constant pressure where the only work involved is the work of expansion. Since delta H is included for conditions in which there is usually work involved, it is more usual that delta U will equal delta H plus work.
Posted: Thu Feb 07, 2019 12:50 pm
For most liquid and aqueous solutions (not gases) dU=dV=qp because there is no change in volume, and thus no change in expansion work. w=0 is when they are equal.