2.00 moles of an ideal gas initially have a pressure of 4.00 atm and a volume of 15.0 L. The gas is isothermally expanded in three steps, each step is done against constant external pressure. The first step has Pext = 3.00 atm, the second step has Pext = 2.00 atm and the final step has Pext = 1.00 atm. Illustrate the expansion with a carefully drawn graph of Pressure vs. Volume, with each step labeled. Please use paper with a grid to do this. a) Calculate the work associated with each step of the isothermal expansion. b) What is the total work done on the gas during this irreversible expansion? c) What would be the total work done by the gas if it were expanded reversibly (instead of in 3 sudden steps)? d) Compare your answers to parts 2(b) and 2(c) - which process took less work to accomplish?