Ok, I must admit that I am becoming a bit confused about these concepts. I understand that enthalpy is u + Pv, and entropy has something to do with molecular randomness. I was fine until we started to solve for heat transfer when dealing with entropy and now I am confused, sometimes we use:(adsbygoogle = window.adsbygoogle || []).push({});

Q=m(u2-u1) to describe heat transfer

and other times we use:

Q=m(h2-h1)

Can anyone please explain to me how to tell which should be used where? I know that its a very important concept that i must have missed.

Thanks

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# Homework Help: Internal energy vs. Enthalpy vs. Entropy

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