An insulated cylinder contains an ideal monatomic gas at temperature 300 K and volume V1. Two different processes take the gas to a final volume V2>V1 while the cylinder remains thermally insulated from the surroundings.
Process A: The piston is moved outward extremely slowly so that the gas remains essentially in internal equilibrium at every stage.
Process B: The piston is suddenly removed, allowing the gas to expand freely into the new volume.
Assume the gas behaves ideally throughout and that no energy crosses the system boundary as heat or work except that associated with the piston motion described above.
(1) For each process, describe qualitatively how the entropy of the gas changes between the initial and final states.
(2) For each process, discuss whether any entropy change occurs in the surroundings. Justify your answer.
(3) For each process, determine the sign (positive, negative, or zero) of the total entropy change of the universe and explain what this implies about the reversibility of the process.