ME/CH EN 2300 Thermodynamics I Homework #13 Due Friday April 27 th 1. (7-88 ) An insulated piston cylinder device initially contains 300 L of air at 120 kPa and 17 C. Air is now heated for 15 minutes by a 200-W resistance heater placed inside the cylinder. The pressure of the air is maintained constant during the process. Determine the entropy of the air assuming (a) constant specific heats and (b) variable specific heats. 2. (7-92) An insulated rigid tank is divided into two equal parts by a partition. Initially, one part contains 5 kmol of an ideal gas at 250 kPa and 40 C, and the other side is evacuated. The partition is now removed and the gas fills the entire tank. Determine the total entropy change during this process. 3. (7-95) An insulated rigid tank contains 4 kg of argon gas at 450 kPa and 30 C. A valve is now opened and argon is allowed to escape until the pressure in the tank drops to 200 kPa. Assuming the argon remaining inside the tank has undergone a reversible, adiabatic process, determine the final mass in the tank. 4.
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