Hi, can someone PLEASE explain
When some process is very endothermic/exothermic, the difference between the enthalpy and the internal energy is negligible? THANK YOU ALL

Question

Hi, can someone PLEASE explain
When some process is very endothermic/exothermic, the difference between the enthalpy and the internal energy is negligible? THANK YOU ALL

anonymous · Answer

@Kainui

kainui · Answer

Well if you find an equation relating the two quantities I think maybe that will make it clear.  I believe the definition of enthalpy is something like this; 

$$\Large H=U+PV$$ During a really endothermic or exothermic process if the state of the system remains the same, like all liquid for example, then there won't be much of a volume or pressure change, leaving the PV term to be nearly zero.

There might be a flaw in this argument, there are kind of a lot of different things to consider in thermodynamics so I can't really say I'm 100% confident about this. If you have some other equations relating Internal Energy and Enthalpy, you should find them and see if you can make a similar argument as to why the the other terms would become negligible.

anonymous · Answer

As always, Thanks a lot! You really clarified this topic to me! Have a stupendous weekend!

kainui · Answer

You too! :P