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1122enthalpy
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Hi I'm new to this site, so I'm not sure where to post this question but chemistry seemed fitting.
I'm current taking 2 thermo classes, engineering and chemistry, and I'm having trouble with the concept of enthalpy.
This is what I believe I understand. I Hope the following is all correct if not please correct me.
H= U + PV
The heat exchanged in a closed system under constant pressure is equal to (delta)H= q(for constant pressure). Which would make (delta)H's physical interpretation the heat added or lost to the system under constant pressure.
The heat exchanged in closed system under constant volume is equal to (delta)U=q(for constant volume) meaning the heat added or lost to the system under constant volume is equal to the change in internal energy
Now to the actual question does enthalpy have a physical meaning in this particular scenario?
Under a closed system in which pressure and volume are not constant
the change in enthalpy would be (delta)H= (delta)U + delta(PV)
which would make (delta)H= (delta)U + V(delta)(P) +P(delta)(V)
However V(delta)P seems to not have a physical meaning either. But if you subtract that term from both sides you get
(delta)H-V(delta)P=deltaU+P(delta)V which I believe would equal this
(delta)q=(delta)U+P(delta)V
so is V(delta)P just a correction term to obtain the heat from the change in enthalpy? or do both of them actually have a physical meaning?
Thanks in advance for any help
I'm current taking 2 thermo classes, engineering and chemistry, and I'm having trouble with the concept of enthalpy.
This is what I believe I understand. I Hope the following is all correct if not please correct me.
H= U + PV
The heat exchanged in a closed system under constant pressure is equal to (delta)H= q(for constant pressure). Which would make (delta)H's physical interpretation the heat added or lost to the system under constant pressure.
The heat exchanged in closed system under constant volume is equal to (delta)U=q(for constant volume) meaning the heat added or lost to the system under constant volume is equal to the change in internal energy
Now to the actual question does enthalpy have a physical meaning in this particular scenario?
Under a closed system in which pressure and volume are not constant
the change in enthalpy would be (delta)H= (delta)U + delta(PV)
which would make (delta)H= (delta)U + V(delta)(P) +P(delta)(V)
However V(delta)P seems to not have a physical meaning either. But if you subtract that term from both sides you get
(delta)H-V(delta)P=deltaU+P(delta)V which I believe would equal this
(delta)q=(delta)U+P(delta)V
so is V(delta)P just a correction term to obtain the heat from the change in enthalpy? or do both of them actually have a physical meaning?
Thanks in advance for any help