An ideal gas contained in a piston–cylinder device expands isothermally at 20°C from state 1 to state 2.

A. If the expansion process is reversible and 100 kJ of heat is transferred from the surroundings to the gas, determine the increase in entropy (kJ/K) of the gas.

B. If the expansion process between these same two states had been internally irreversible, would the entropy increase be greater than, the same as, or less than the entropy increase found in part A? Explain.

C. For an irreversible process between the same two states, will the heat transfer to the gas be greater than, the same as, or less than the 100 kJ for the reversible process? Explain.