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Topic: Is it reasonable to derive this formula?  (Read 2248 times)

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Offline Wienerbroed

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Is it reasonable to derive this formula?
« on: July 07, 2021, 12:11:32 PM »
I need to calculate the change in internal energy of a reaction.

Is it reasonable to derive the formula ΔU = ΔH - P * ΔV to ΔU = ΔH - nRT?

In this case the pressure is constant, meaning ΔH = q. All terms should then have the unit joules.
I don't have a measurement for the volume.
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Offline Orcio_87

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Re: Is it reasonable to derive this formula?
« Reply #1 on: July 07, 2021, 01:27:53 PM »
True, as pΔV = Δn RT.
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Offline Borek

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Re: Is it reasonable to derive this formula?
« Reply #2 on: July 08, 2021, 02:49:22 AM »
Quote from: Orcio_Dojek on July 07, 2021, 01:27:53 PM
True, as pΔV = Δn RT.

n and Δn are not synonyms.
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Offline Orcio_87

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Re: Is it reasonable to derive this formula?
« Reply #3 on: July 08, 2021, 03:41:20 AM »
Right, I hope that Wienebroed sees the difference in his equation.
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