ANSWER ALL QUESTIONS.

3-68 A 0.3-m3 rigid vessel initially contains saturated liquid-vapor mixture of water at 150C. The water is now heated until it reaches the critical state. Determine the mass of the liquid water and the volume occupied by the liquid at the initial state. Answers: 96.1 kg, 0 .1 0 5 m 3 Ideal Gas 3-69C What is the difference between mass and molar mass? How are these two related? 3-70C Under what conditions is the ideal-gas assumption suitable for real gases? 3-71C What is the difference between R and /?? How are these two related? 3-72C Propane and methane are commonly used for heating in winter, and the leakage of these fuels, even for short periods, poses a fire danger for homes. Which gas leakage do you think poses a greater risk for fire? Explain. 3-73 What is the specific volume of nitrogen at 300 kPa and 227C? 3-74E A 3-ft3 container is filled with 2-lbm of oxygen at a pressure of 80 psia. What is the temperature of the oxygen?

3-75 A 2-kg mass of helium is maintained at 300 kPa and 27C in a rigid container. How large is the container, in m3? 3-76 A spherical balloon with a diameter of 9 m is filled with helium at 27C and 200 kPa. Determine the mole number and the mass of the helium in the balloon. Answers: 3 0 .6 k mol, 123 kg 3-77 Reconsider Prob. 3-76. Using EES (or other) K S software, investigate the effect of the balloon diameter on the mass of helium contained in the balloon for the pressures of (a) 100 kPa and (b) 200 kPa. Let the diameter vary from 5 m to 15 m. Plot the mass of helium against the diameter for both cases.

78 A 1-m3 tank containing air at 25C and 500 kPa is connected through a valve to another tank containing 5 kg of air at 35C and 200 kPa. Now the valve is opened, and the entire system is allowed to reach thermal equilibrium with the surroundings, which are at 20C. Determine the volume of the second tank and the final equilibrium pressure of air. Answers: 2.21 m3 , 28 4 .1 kPa

3-79E 2.l of air at 65F and 32 psia is contained in an elastic tank. What is the volume of the tank? If the volume is doubled at the same pressure, determine the final temperature. 3-80 A rigid tank contains an ideal gas at 1227C and 200 kPa gage. The gas is cooled until the gage pressure reads 50 kPa. If the atmospheric pressure is 100 kPa, determine the final temperature of the gas.

3-81 A rigid tank whose volume is unknown is divided into two parts by a partition. One side of the tank contains an ideal gas at 927C. The other side is evacuated and has a volume twice the size of the part containing the gas. The partition is now removed and the gas expands to fill the entire tank. Heat is now applied to the gas until the pressure equals the initial pressure. Determine the final temperature of the gas. Answer: 3327C FIGURE P 3 -81 3-82 Argon in the amount of 0.6 kg fills a 0.05-m3 piston cylinder device at 550 kPa. The piston is now moved by changing the weights until the volume is twice its original size. During this process, argon's temperature is maintained constant. Determine the final pressure in the device.

3-83 The pressure in an automobile tire depends on the temperature of the air in the tire. When the air temperature is 25C, the pressure gage reads 210 kPa. If the volume of the tire is 0.025 m3, determine the pressure rise in the tire when the air temperature in the tire rises to 50C. Also, determine the amount of air that must be bled off to restore pressure to its original value at this temperature. Assume the atmospheric pressure is 100 kPa.

3-85C What is the principle of corresponding states? 3-86C How are the reduced pressure and reduced temperature defined? 3-87 Determine the specific volume of superheated water vapor at 15 MPa and 350C, using (a) the ideal-gas equation, (b) the generalized compressibility chart, and (c) the steam tables. Also determine the error involved in the first two cases. Answers: (a) 0 .0 1 9 1 7 m3/kg, 6 7 .0 percent, (M 0 .0 1 2 4 6 m 3/kg, 8 .5 percent, (c) 0 .0 1 1 4 8 m3/kg 3-88 Reconsider Prob.

3-87. Solve the problem using the generalized compressibility factor feature of the EES software. Again using EES, compare the specific volume of water for the three cases at 15 MPa over the temperature range of 350 to 600C in 25C intervals. Plot the percent error involved in the ideal-gas approximation against temperature, and discuss the results. 3-89 Determine the specific volume of refrigerant-134a vapor at 0.9 MPa and 70C based on (a) the ideal-gas equation, (b) the generalized compressibility chart, and (c) data from tables. Also, determine the error involved in the first two cases. 3-90 Determine the specific volume of superheated water vapor at 3.5 MPa and 450C based on (a) the ideal-gas equation, (b) the generalized compressibility chart, and (c) the steam tables. Determine the error involved in the first two cases.

3-91E Ethane in a rigid vessel is to be heated from 80 psia and 100F until its temperature is 540F. What is the final pressure of the ethane as predicted by the compressibility chart? 3-92 Ethylene is heated at constant pressure from 5 MPa and 20C to 200C. Using the compressibility chart, determine the change in the ethylene's specific volume as a result of this heating. Answer: 0 .0 1 7 2 m3/kg 3-93 Saturated water vapor at 350C is heated at constant pressure until its volume has doubled. Determine the final temperature using the ideal gas equation of state, the compressibility charts, and the steam tables. 3-94E Saturated water vapor at 400F is heated at constant pressure until its volume has doubled. Determine the final temperature using the ideal gas equation of state, the compressibility charts, and the steam tables.

3-95 Methane at 8 MPa and 300 K is heated at constant pressure until its volume has increased by 50 percent. Determine the final temperature using the ideal gas equation of state and the compressibility factor. Which of these two results is more accurate? 3-96 What is the percentage of error involved in treating carbon dioxide at 5 MPa and 25C as an ideal gas? Answer: 4 5 percent 3-97 Carbon dioxide gas enters a pipe at 3 MPa and 500 K at a rate of 2 kg/s. C 0 2 is cooled at constant pressure as it flows in the pipe and the temperature of C 0 2 drops to 450 K at the exit. Determine the volume flow rate and the density of carbon dioxide at the inlet and the volume flow rate at the exit of the pipe using (a) the ideal-gas equation and (b) the generalized compressibility chart. Also, determine (c) the error involved in the first case. 3-98 Determine the specific volume of nitrogen gas at 10 MPa and 150 K based on (a) the idea-gas equation and (b) the generalized compressibility chart. Compare these results with the experimental value of 0.002388 m3/kg, and determine the error involved in each case. Answers: (a) 0 .0 0 4 4 5 2 m 3/kg, 8 6 .4 percent; (b) 0 .0 0 2 4 0 4 m3/kg, 0 .7 percent Other Equations of State 3-99C What is the physical significance of the two constants that appear in the van der Waals equation of state? On what basis are they determined?

3-100 100 grams of carbon monoxide are contained in a weighted piston-cylinder device. Initially the carbon monoxide is at 1000 kPa and 200C. It is then heated until its temperature is 500C. Determine the final volume of the carbon monoxide treating it as (a) an ideal gas and (b) a -Rubin gas. 3-101 Methane is heated in a rigid container from 80 kPa and 20C to 3()()C. Determine the final pressure of the methane treating it as (a) an ideal gas and (b) . 3-102E Carbon monoxide is heated in a rigid container from 14.7 psia and 70F to 800F. Determine the final pressure of the carbon monoxide treating it as (a) an ideal gas and (b) a Benedict-Webb-Rubin gas.

3-103E Refrigerant-134a at 160 psia has a specific volume of 0.3479 ft3/lbm. Determine the temperature of the refrigerant based on (a) the ideal-gas equation, (b) the van der Waals equation, and (c) the refrigerant tables. 3-104 Nitrogen at 150 K has a specific volume of 0.041884 m Determine the pressure of the nitrogen, using (a) the ideal-gas equation and (b) . Compare your results to the experimental value of 1000 kPa.