Enthalpy: Pressure Change & Problem Solving

[professor]

i understand enthalpy, what it is, how it changes. I have only two questions... first, as enthalpy changes the Pressure can change also (i know it doesent have to, but my book seems to be attempting to tell me that it never changes) and secondly could someone present a problem in which enthalpy could be usefull in solving? (only a concept for a problem would suffice)

 

[GCT]

fortunately enthalpy has an fundamental description. H=U+PV. You can apply calculus, algebra...whatever, but it's not going to help you to assume any absolutes about such concepts. Enthalpy is useful for most situations, if you're given specific limitations, you can even simplify enthalpy to internal energy for instance.

enthalpy doesn't have to be constant pressure, dH=dU+PdV+VdP, and you don't need to have constant pressure, you can even apply enthalpy towards a constant volume process.

 

[professor]

ohh.. duh its just a simplification (or an attempt therof) to help in the finding of volume or pressure or one of the other described variables.. as allways, thanks