I have a question that pertains to how we can recover the initial or previous state in a reversible process and how that becomes impossible with an irreversible process.
In the quasit-static model with a piston there is a classic example where weights are removed in an infinitesimal manner so that the expanding gas never deviates far from equilibrium as we continue the process along an isotherm. In the idealized, reversible process we assume there is no friction or dissipative forces. You can always recover the previous state of the gas just by adding the weights back.
My question is about what happens in an irreversible process if you permit friction. The gas will not push the piston up as far because some of the energy is no longer used to do work in expansion. The energy is lost to friction as heat, so the expansion is less. But if you add the same weight back which was removed, would the piston actually not compress by the same (lessened) amount that it expanded? The friction should be the same whether you're going up or down, but you can't actually recover your previous state since this is not a reversible process.
My thinking is that since the temperature and pressure would change in the irreversible process with friction, that adding the weight back would not give you a compression that equally offsets the expansion when you removed the weight. Is this correct? Or does the gas actually compress to the previous volume but the temperature and pressure have still changed?
***Assume in 1 case that heat remains in gas and in another case that heat is permitted to enter the surroundings