1. The problem statement, all variables and given/known data Use the fundamental eq for the helmholtz eq to find dA for 1 mole of ideal gas as it expands isothermally from 5L to 15L at 298 Kelvin 2. Relevant equations dA = -PdV - SdT PV = nRT 3. The attempt at a solution I tried to solve this the same way I did the problem on the previous page to calculate the isothermal compressibility, but it is not working out. I know that dT is going to equal zero, so dA = -PdV but when I try to calculate P, I am not sure how factor in the change in V. I think I remember doing this at the beginning of the semester, but I can't remember. or find my notes. Any hints?