Internal Energy and Enthalpy


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chrisdinkel_4E
Posts: 33
Joined: Fri Sep 28, 2018 12:17 am

Internal Energy and Enthalpy

Postby chrisdinkel_4E » Wed Feb 13, 2019 10:54 am

Can someone please explain to me the relationship between Internal Energy (U) and Enthalpy (H)

Vy Lu 2B
Posts: 59
Joined: Fri Sep 28, 2018 12:24 am

Re: Internal Energy and Enthalpy

Postby Vy Lu 2B » Wed Feb 13, 2019 11:00 am

Enthalpy is the amount of heat absorbed or released by a system under constant pressure, which essentially is the heat at constant pressure, qp. Since the change in internal energy is equal to the sum of heat and work, enthalpy can be related to change in internal energy if the system is at constant pressure.

Sarah Fatkin 4I
Posts: 71
Joined: Fri Sep 28, 2018 12:27 am

Re: Internal Energy and Enthalpy

Postby Sarah Fatkin 4I » Wed Feb 13, 2019 11:06 am

The change in internal energy (delta U) is equal to q + w, and when the system is at constant pressure, then q = delta H, which is enthalpy.

JiangJC Dis2K
Posts: 72
Joined: Fri Oct 12, 2018 12:16 am

Re: Internal Energy and Enthalpy

Postby JiangJC Dis2K » Wed Feb 13, 2019 11:23 am

Delta U equals delta H + w when pressure is constant. At constant pressure q=delta H. Another helpful equation in this scenario is delta u=delta h-delta n RT. This can be used when you have gas values other thank P and V.


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