作者sokuso123 (nick)
看板Grad-ProbAsk
标题Re: [理工] [热力学]-2nd law
时间Sun Dec 20 00:12:35 2009
※ 引述《hihaka2001 (hihaka)》之铭言：
: 请问大家
: one mole of an ideal gas at 300K is isothermally compressed by a constant
: external pressure equal to the final pressure.
: At the end of the process, P=Pex. Because P is not equal to Pex at all but
: the final state, this state is "irreverisble" The initial volume is 25L and
: the final volume is 10L . The surrounding is 300K
: Calculate ΔS ,ΔS (surrounding) ΔS(total)
: 我的问题是
: 外界的热量要怎麽算
: 也就是说ΔS (surrounding)要怎麽算
Q-W=ΔU
而ΔU=CpΔT=0
所以 Q=W
V2
等温过程W=mRT1 ln ----
v1
10
=28.8*10^-3*0.287*300*ln----
25
=-2.27 kJ
Q=-2.27kJ
ΔSsur=2.27/300=7.57*10^-3 kJ/k
--
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◆ From: 140.113.198.249
※ 编辑: sokuso123 来自: 140.113.198.249 (12/20 00:13)
1F：推 hihaka2001:你算到系统了 他的SURR的s是12.45 12/20 00:16