- #1
stuffchemistry
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I'm really confused about Energy and Entropy's equations of state, and how their differentials work.
So I find everywhere that H = U + PV. And so dH = d(U +PV) = dU + PdV + VdP
Ok, that makes sense. But then I look at energy and try to get the equation of state
dU = δqrev + δwrev.
That also makes sense. But what is the equation of state for just U itself? Why is U = q + PV not an equation of state? Why is only the differential the equation of state? How come you can't take the differential of U = q + PV to get dU = dq + PdV + VdP?
Is the equation of state for energy just U = H - PV, rearranging H = U + PV?
I'm really lost in this...
So I find everywhere that H = U + PV. And so dH = d(U +PV) = dU + PdV + VdP
Ok, that makes sense. But then I look at energy and try to get the equation of state
dU = δqrev + δwrev.
That also makes sense. But what is the equation of state for just U itself? Why is U = q + PV not an equation of state? Why is only the differential the equation of state? How come you can't take the differential of U = q + PV to get dU = dq + PdV + VdP?
Is the equation of state for energy just U = H - PV, rearranging H = U + PV?
I'm really lost in this...