State Functions and Order of Diff and Enthelpy

[cns]

I am working on some basic derivations for thermodyhnamics, my book doesn't explicitly state things so I am not sure if my current assumptions are correct?

1) All state functions (U,T,P,G,A) are exact differentials AND all non-state functions are INexact differntials. So if I take the 2nd derivative, I will get the same function for M and N in the example of dz = M(x,y) + N(x,y)

2) What does my book mean when it says that the order of differentiation doesn't matter for state functions?

- what do they mean by order of differentiation? does t

3) How do I calculate (delta)Enthalpy when volume is constant? It looks like it would be qv but when it comes to bomb calorimeters my book keeps using qp?

If H = U + PV, shouldn't constant volume make H = U? for reversible and irrev?

H = q/T only pressure is constant + reversible?

Why is it that my book shows dH = dU + PdV RATHER THAN d(PV) = dU+ VdP+PdV (expanding for chainge P and V?)

Thank YOU :D

 

[Chestermiller]

I am working on some basic derivations for thermodyhnamics, my book doesn't explicitly state things so I am not sure if my current assumptions are correct?

1) All state functions (U,T,P,G,A) are exact differentials AND all non-state functions are INexact differntials. So if I take the 2nd derivative, I will get the same function for M and N in the example of dz = M(x,y) + N(x,y)

2) What does my book mean when it says that the order of differentiation doesn't matter for state functions?

- what do they mean by order of differentiation? does t

It means that $$\frac{\partial ^2 U}{\partial T\partial V}=\frac{\partial^2 U}{\partial V\partial T}$$

3) How do I calculate (delta)Enthalpy when volume is constant? It looks like it would be qv but when it comes to bomb calorimeters my book keeps using qp?

Enthalpy is independent of process path, so it is not specifically related to qv or qp, except when employed to analyze a particular process.

If H = U + PV, shouldn't constant volume make H = U? for reversible and irrev?

Again, it is independent of process path and, if V is constant, you still have H depending on P. Reversible or irreversible is irrelevant.

H = q/T only pressure is constant + reversible?

Neither. The units don't match.

Why is it that my book shows dH = dU + PdV RATHER THAN d(PV) = dU+ VdP+PdV (expanding for chainge P and V?)

Maybe your book is referring to a case in which the initial and final pressures are the same.