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Unformatted text preview: 60. (a) The ideal gas is diatomic, so f = 5 (see Table 203). Since this is an isobaric (constant pressure) process, with no change in the number of moles, then the ideal gas in ratio form (see Sample Problem 201) leads to V f V i = T f T i = 8 3 . With C V = f 2 R , Eq. 214 gives S gas = nR ln 8 3 + n 5 2 R ln 8 3 where n is the number of moles (25 mol), not to be confused with the number of reservoirs (also denoted n in the later parts of this problem). Consequently, we obtain S gas = 7 2 (25 mol) 8 . 31 J mol K ln 8 3 = 713 J / K . Since Q = nC p T for this process, the entropy change of the reservoir (which transfers energy Q to the gas, so it (the heat) is negativevalued in this context) is (using Eq. 212) S res = Q T = n ( 7 2 R ) (800 K 300 K) 800 K = 454 J / K . Therefore, S system = S gas + S res = 259 J/K....
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This note was uploaded on 11/12/2011 for the course PHYS 2001 taught by Professor Sprunger during the Fall '08 term at LSU.
 Fall '08
 SPRUNGER
 Physics

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