Calculate the change in entropy of the universe for the process described in Problem 2.28.
Repeat for Problem 2.29.

Problem 2.28 

Consider a piston–cylinder assembly that contains 1 mole of ideal gas, A. The system is well insulated. Its initial volume is 10 L and initial pressure, 2 bar. The gas is allowed to expand against a constant external pressure of 1 bar until it reaches mechanical equilibrium. Is this a reversible process?
What is the fi nal temperature of the system? How much work was obtained? For gas A: cV = 15/22 R.

Problem 2.29

For the well-insulated piston–cylinder assembly containing 1 mole of ideal gas described in Problem 2.28, describe the process by which you can obtain the maximum work from the system.
Calculate the value for the work. What is the fi nal temperature? Why is T lower than that calculated in Problem 2.28?