Enthalpy equation

[Arjun Sharma 1D]

In the equation H= U + PV, where does the PV at the end come from?

[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!

[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.