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Enthalpy equation

Posted: Sun Jan 21, 2018 4:26 pm
by Arjun Sharma 1D
In the equation H= U + PV, where does the PV at the end come from?

Re: Enthalpy equation

Posted: Sun Jan 21, 2018 4:39 pm
by Emily Duggan 1F
It comes from the equation for calculating internal heat when changing the energy of a closed system at a constant pressure. That equation is U = H - PV, so when rearranged you can get H = U + PV

hope this helps!

Re: Enthalpy equation

Posted: Sun Jan 21, 2018 4:51 pm
by camrynpatterson3C
Work, at constant pressure, is equal to -PdeltaV.
The change in internal energy of a system is equal to q + w. Therefore, deltaU is equal to q + (-PdeltaV).
At constant pressure, q is equal to deltaH.
So, deltaU = deltaH + (-PdeltaV).

Hope that helps a little.