Calculate the work done by a gas as it slowly expands from point A to point B on the pV diagram shown at right. 2. If 500 J of heat entered the gas in the previous problem, what is the change in the internal energy of the gas? XXXXXXXXXXx 10 J of heat enters an ideal gas 5 as it expands at a constant T = 77 C to o four times its initial volume. How many moles of gas are there? 4. The plates on a submarine rupture, and the inrushing water adiabatically compresses the sub's air (an ideal diatomic gas) to 1/8 of its original volume. If the air was initially at a pressure of 1 atm and a temperature of 27 C, find the final o pressure and temperature of the compressed air. 5. A steam power plant takes in heat at a temperature of 650 K and exhausts heat to a river at a temperature of 300 K. What is the maximum possible efficiency of the power plant? 6. In #5, if 1.5 x 10 J of heat enters the river in 0.7 sec, 7 find the power output of the maximum efficiency power plant. 7. A steam power plant produces 1.5 x 10 W of power. It 7 exhausts heat at a rate of 2.5 x 10 W to a river at a 7 temperature of 5 C. Find the efficiency of the power plant. o 8. Find the temperature of the steam entering the power plant above if its actual efficiency is 70% of the maximum efficiency XXXXXXXXXXmoles of an ideal diatomic gas go through the cycle shown at right. The temperatures at points A, B, and C are 216.5 K, 192.5 K, and 144.3 K respectively. Find the heat entering and leaving the gas, and the cycle's efficiency. 10. For the cycle of #9, find the change in entropy of the gas for the processes A -> B, B -> C, and C -> A XXXXXXXXXXkg of water at 0 C is heated to a temperature of 100 C. o o Find the change in entropy of the water XXXXXXXXXXkg of water at 100 C vaporizes into steam at 100 C. o o Find its change in entropy. 13. Four moles of an ideal gas expands at constant temperature until its pressure is reduced to half of its initial value. What is the change in entropy of the gas? Data: ice: c = 2090 J/kg K . water: c = 4190 J/kg K . steam: c = 2010 J/kg K . Lf = 3.33 x 10 J/kg 5 Lv = 2.26 x 10 J/kg 6 Answers: XXXXXXXXXXJ XXXXXXXXXXJ XXXXXXXXXXmoles XXXXXXXXXXatm, 416 C o XXXXXXXXXXx 10 W XXXXXXXXXXC 7 o (9) QH C = 37,500 J, Q = -35,100 J, XXXXXXXXXX, -210 J/K, +210 J/K XXXXXXXXXXJ/K XXXXXXXXXXx 10 J/K XXXXXXXXXXJ/K
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