Hello all, i have been asked a question about a lump of iron being warmed, and to calculate the difference between enthalpy and internal energy. I did some algebra and found that the change in the product pV , in the case of a liquid would suffice. But, since the volume doesn't change (Assumed, still solid) the change is down to the pressure. Now, for a gas, pV/T is a constant so i would argue that if T increases, p should increase. But does this whole idea work for a solid? does it exert a pressure, and does it manifest in such a form that my fluid derivations (pV/T = constant) hold for said solid? Regards, James.