# Problem 3-2 - Example 3-2 A gas with a molecular weight of...

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Example 3-2 A gas with a molecular weight of 147 is compressed isothermally and reversibly in a piston-cylinder assembly from an initial pressure of 60 kPa to a final pressure of 180 kPa. The initial volume and temperature are 344 cm 3 and 10°C. Determine a) the heat transferred b) the work done Solution: a) For a reversible process () 21 QT S S =− For an ideal gas, the entropy change is 22 11 ln ln p TP R ssc TMP ⎛⎞ −= ⎜⎟ ⎝⎠ Since 12 TT = , this reduces to 2 1 kJ 8.314 180 kPa kJ kmol K ln ln 0.0621 kg 60 kPa kg K 147 kmol P R ss MP = = Qm T s s To find the mass, use the ideal gas law 1 PVM m RT = 3 3 1 m kg 60 kPa 344 cm 147 100 cm kmol 0.00129 kg kJ 8.314 10 273 K kmol K m == +

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Heat may now be calculated as
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Problem 3-2 - Example 3-2 A gas with a molecular weight of...

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