1. The problem statement, all variables and given/known data I'm probably over thinking this question. An ideal gas is placed in a thin walled aluminum cylinder and slowly compressed to 25% of its original volume. The process is best described as adiabatic, isothermal, isochoric, or isobaric? 2. Relevant equations none 3. The attempt at a solution I know the difference between the different processes. I'm just not sure how the thin walled aluminum container adds to the problem or if it does. In similar problems, a thick walled aluminum container represented constant volume. Obviously the answer is not isochoric since the volume changes. I don't think it is adiabatic because the process happens slowly. That leaves isothermal and isobaric. I know isothermal must happen slowly enough so thermal equilibrium is maintained. (This is what I suspect is the answer). How would a thin walled aluminum container affect pressure?