Homework#9 DCGN209-Spring10: p. 1 of 2
I.
Study Questions & Problems (not to hand in). A. Exactly 1.2028 moles of He(g) initially exerts a pressure of 800 kPa at 26.85 0C. The gas expands isothermally against a constant opposing pressure of 400.0 kPa to a final pressure of 400.0 kPa. B. Exactly 1.2028 moles of He(g) initially exerts a pressure of 800 kPa at 26.85 0C. The gas expands isothermally and reversibly to a final pressure of 400.0 kPa. C. Exactly 1.2028 moles of He(g) initially exerts a pressure of 800 kPa at 26.85 0C. The gas is heated at constant volume to a final temperature of 400.0 K.
CV =
3 R 2
D. Exactly 1.2028 moles of He(g) initially exerts a pressure of 800 kPa at 26.85 0C. The gas is heated at constant pressure to a final temperature of 400.0 K. E. Exactly 1.2028 moles of CO2(g) initially exerts a pressure of 800 kPa at 26.85 0 C. The gas is heated at constant pressure to a final temperature of 400.0 K.
C P = 44.22 + 8.79 x 10 3 T 8.62 x 10 +5 T 2
(
J ) mole K
F. Exactly 1.2028 moles of H2O, initially solid at 0.00 0C & 1.000 atm, is completely converted to liquid at 0.00 0C & 1.000 atm.
fus H = 6010
J mole
G. Exactly 1.2028 moles of H2O, initially liquid at 100.0 0C & 1.000 atm, is completely converted to gas at 100.0 0C & 1.000 atm.
vap H = 40,670
J mole
H. Exactly 1.2028 moles of He(g) exerts initially a pressure of 800 kPa at 26.85 0C. The gas expands adiabatically and reversibly to a final pressure of 400.0 kPa. Answers
J all K
A. 6.932 F. 26.46
B. 6.932 G. 131.03
C. 4.316 H. Zero
D. 7.193
E. 13.839
DCGN209-Spring10: Homework#9 p. 2 of 2
II. Hand-In Problems Due: 2:00 PM, Wednesday March 31, 2010
1.2028 moles of He(g) a monatomic ideal gas for which CV = 3/2R (per mole) initially occupies a volume of 10.00 L at a temperature of 100.0 K. The gas undergoes a two-step process: [1] compressed adiabatically & reversibly until its temperature increases to 150.0 K; then [2] the gas is heated at constant pressure to a final temperature of 200.0 K.
A. (3 pts) Calculate the initial pressure, P1. B. (7 pts) Show that the intermediate volume, V2, is 5.443 L. C. (3 pts) Calculate the intermediate pressure, P2. D. (4 pts) Calculate the final volume, V3. E. (3 pts) Briefly explain why S for step #1 is zero. F. (7 pts) Calculate S for the overall process, using the above path. G. (13 pts) Show that S is path independent by calculating S for the overall process. In this case, assume that you know only the initial temperature & volume, and the final temperature & volume, but not the details of the steps. That is, devise a different path between the initial and final states, and then calculate S for your path.