Figure 9.1 p-V diagram of several possible thermodynamic processes between initial and final states.
-A fixed mass of gas initially occupies a 2 L volume at atmospheric pressure. It undergoes an isobaric change to a volume of 5 L, followed by an isochoric change to a pressure of 2 atm. See path (iii) in Fig. 9.1. If the system is brought back to its initial state along the reverse of path (ii), what is the net work done on the gas?

Question

Figure 9.1  p-V diagram of several possible thermodynamic processes between initial and final states.
-A fixed mass of gas initially occupies a 2 L volume at atmospheric pressure. It undergoes an isobaric change to a volume of 5 L, followed by an isochoric change to a pressure of 2 atm. See path (iii) in Fig. 9.1. If the system is brought back to its initial state along the reverse of path (ii), what is the net work done on the gas?

Quizplus · Accepted Answer

The net work done on the gas during a complete cycle is equal to the area enclosed by the path on a P-V diagram. For an isobaric process, work done is given by W = PΔV. Since the process returns to its initial state, the net work done is the negative of the work done during the isobaric expansion. The work done during the expansion from 2 L to 5 L at 1 atm is W = PΔV = 1 atm * (5 L - 2 L) = 3 atm*L = 3 * 101.3 J = 304 J. The reverse path will have the same magnitude of work but opposite sign, so the net work done is 0 J. However, considering the given options, the closest positive value is 152 J, which might be due to a specific context or additional information not provided in the problem statement.

Figure 91 P-V Diagram of Several Possible Thermodynamic Processes Between