[georg gill]

http://bildr.no/view/1101698

In the picture above is a example where enthalpy is used and a page from my book where they use enthalpy to describe a calormeter

In the page with calormeter (look just to the right of the cup) they say that since dP and dV of the surroundings are 0 dH=q since E=q+w and w=PdV=0 since dV=0. So one would assume PV in H is for surroundings. But in the example they find H while using data of the system. I guess I wonder what is PV part of enthalpy is it surroundings or is it system?

[georg gill]

http://en.wikipedia.org/wiki/Enthalpy#Relationship_to_heat

here they describe enthalpy relationship to heat in the end they say there is a restrction. If they were not talking about relation to heat and

dH=dE+dPV

what would one use this for. For what situations does this apply?

[Pradeep]

Enthalpy of a system is

H= U + PV              U is the internal energy, P is pressure on the system, V is the volume of the systsm.

H = U +Vdp +PdV   

But, U = Q + W    (Work done on the system)

W = -PdV (for a reversibe process)

H = Q -PdV + PdV

H = Q