- #1
kq6up
- 368
- 13
I understand why entropy (a state function) is very useful in chemistry. Since most chemistry systems are at constant pressure, ##\Delta H=Q_v## from the derivation below:
##H=U+PV##
##dH=dU+dPV+PdV##
##dU=\delta Q-\delta W##
## dU=\delta Q-PdV##
## dH=\delta Q+dPV##
##dPV=0##
## dH=\delta Q_v##
However, for constant volume work is not done, so that seems to leave this pesky ##dPV## term. That is:
##dH=\delta Q_p+dPV## What is the meaning of this term. ##PdV## is obviously microscopic work, but what the other term resulting from the product rule means physically escapes me.
Thanks,
Chris
##H=U+PV##
##dH=dU+dPV+PdV##
##dU=\delta Q-\delta W##
## dU=\delta Q-PdV##
## dH=\delta Q+dPV##
##dPV=0##
## dH=\delta Q_v##
However, for constant volume work is not done, so that seems to leave this pesky ##dPV## term. That is:
##dH=\delta Q_p+dPV## What is the meaning of this term. ##PdV## is obviously microscopic work, but what the other term resulting from the product rule means physically escapes me.
Thanks,
Chris