ΔH = ΔU + PΔV

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905022356
Posts: 48
Joined: Mon Oct 02, 2017 7:19 am

ΔH = ΔU + PΔV

Postby 905022356 » Sat Jan 20, 2018 1:05 pm

I dont understand why enthalpy is defined as ΔH = ΔU + PΔV. Can someone please explain where this equation came from to me?

Alvin Tran 2E
Posts: 39
Joined: Fri Sep 29, 2017 7:06 am

Re: ΔH = ΔU + PΔV

Postby Alvin Tran 2E » Sat Jan 20, 2018 1:11 pm

The equation ΔU = q + w comes from the fact that the internal energy of a closed system can be changed by heating/cooling or compression/expansion. Under constant pressure, ΔU = qp + w. qp = ΔH and w = -PΔV. If you plug those in and rearrange, you get the equation ΔH = ΔU + PΔV.

905022356
Posts: 48
Joined: Mon Oct 02, 2017 7:19 am

Re: ΔH = ΔU + PΔV

Postby 905022356 » Sun Jan 21, 2018 5:22 pm

This was helpful, thanks!


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