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Unformatted text preview: 0.169 kJ/K 7–52 Reconsider Prob. 7–51. Using EES (or other)
software, study the effect of the mass of the iron
block on the final equilibrium temperature and the total entropy change for the process. Let the mass of the iron vary
from 1 to 10 kg. Plot the equilibrium temperature and the total entropy change as a function of iron mass, and discuss
the results. 7–61 Oxygen gas is compressed in a pistoncylinder device
from an initial state of 0.8 m3/kg and 25°C to a final state of
0.1 m3/kg and 287°C. Determine the entropy change of the
oxygen during this process. Assume constant specific heats.
7–62 A 1.5m3 insulated rigid tank contains 2.7 kg of carbon
dioxide at 100 kPa. Now paddlewheel work is done on the
system until the pressure in the tank rises to 120 kPa. Determine the entropy change of carbon dioxide during this process
Answer: 0.323 kJ/K
in kJ/K. Assume constant specific heats. CO2
1.5 m3
100 kPa
2.7 kg 7–53 A 50kg iron block and a 20kg copper block, both initially at 80°C, are dropped into a large lake at 15°C. The...
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This document was uploaded on 11/28/2012.
 Spring '09

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