Chapter 20, Problem 20.45P

CALC A cylinder contains oxygen at a pressure of 2.00 atm. The volume is 4.00 L, and the temperature is 300 K. Assume that the oxygen may be treated as an ideal gas. The oxygen is carried through the following processes:

1. (i) Heated at constant pressure from the initial state (state 1) to state 2, which has T = 450 K.
2. (ii) Cooled at constant volume to 250 K (state 3).
3. (iii) Compressed at constant temperature to a volume of 4.00 L (state 4).
4. (iv) Heated at constant volume to 300 K, which takes the system back to state 1.

(a) Show these four processes in a pV-diagram, giving the numerical values of p and V in each of the four states. (b) Calculate Q and W for each of the four processes. (c) Calculate the net work done by the oxygen in the complete cycle. (d) What is the efficiency of this device as a heat engine? How does this compare to the efficiency of a Carnot-cycle engine operating between the same minimum and maximum temperatures of 250 K and 450 K?