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Capitolo 5

Il bilancio entropico

$OOD OXFH GL FLz O¶RJJHWWR GHL GXH HQXQFLDWL VRQR SURSULR OH PDFFKLQH WHUPLFKH L PRWRUL

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nunciato di Clausius.

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Secondo

Principio della Termodinamica

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FRVD QRQ SXz DYYHQLUH

YLHQH HVSUHVVR PHGLDQWH GXH HQXQFLDWL GLVWLQWL VHEEHQH ULJXDUGLQR HQWUDPEL OH PDFFKL

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QH WHUPLFKH VL WUDWWD FRPXQTXH GL PDFFKLQH FRPSOHWDPHQWH GLYHUVH WUD ORUR

ID ULIHULPHQWR DG DPELWL WHFQRORJLFL PROWR VSHFL¿FL VHPEUD LPSUREDELOH SRWHUQH WUDUUH

GHOOH FRQVHJXHQ]H GL FDUDWWHUH JHQHUDOH

QHVVXQR GHL VXRL HQXQFLDWL VL SUHVWD DG HVVHUH IRUPXODWR PDWHPDWLFDPHQWH

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XQ XQLFR SULQFLSLR ¿VLFR FRQLXJDWR LQ DPELWL GLYHUVL

GLPRVWUDUH FKH HVLVWH XQ OLPLWH WHRULFR SHU OH SUHVWD]LRQL GHOOH PDFFKLQH WHUPLFKH

LQGLYLGXDQGRQH DQFKH LO YDORUH

LQGLYLGXDUH OH FDXVH GL SHQDOL]]D]LRQH GHOOH SUHVWD]LRQL GHOOH PDFFKLQH WHUPLFKH UHDOL

ULVSHWWR DO OLPLWH WHRULFR PHQ]LRQDWR DO SXQWR SUHFHGHQWH

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¿QRUD KD ULFKLHVWR O¶LPSLHJR GL XQ JDV LQ¿QLWDPHQWH UDUHIDWWR

LQWURGXUUH XQD QXRYD YDULDELOH GL VWDWR GHQRPLQDWD

entropia

H TXDQWL¿FDUQH OH YDULD]LRQL

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GHOOD VXD HQWURSLD H JOL VFDPEL WHUPLFL D FXL q VRJJHWWR WDOH ELODQFLR SRWUj HVVHUH FRQ

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VLGHUDWR FRPH O¶HVSUHVVLRQH PDWHPDWLFD GHO 6HFRQGR 3ULQFLSLR

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TXDQWL¿FDUH OH YDULD]LRQL GHOOD JUDQGH]]D HQHUJLD LQWHUQD

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LQIDWWL LQ TXHVWR FDVR OD ORJLFD PDWHPDWLFD FRQVHQWH GL DIIHUPDUH FKH VL WUDWWD GL DIIHUPD]LRQL

WUD ORUR HTXLYDOHQWL R LQ DOWUL WHUPLQL FKH HVVH FRVWLWXLVFRQR GXH IDFFH GHOOD VWHVVD PHGDJOLD

6L FRQVLGHULQR GXQTXH GXH VRUJHQWL D WHPSHUDWXUD

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FLDQR ODYRUDUH GXH PDFFKLQH WHUPLFKH XQ PRWRUH H XQD PDFFKLQD IULJRULIHUD &RPH LQGLFDWR

LQ )LJXUD D VL VXSSRQJD GDSSULPD FKH O¶HQXQFLDWR GL .HOYLQ ± 3ODQFN VLD IDOVR H TXLQGL

FKH VLD SRVVLELOH IDU IXQ]LRQDUH LO PRWRUH FRQYHUWHQGR LQ SRWHQ]D PHFFDQLFD WXWWR LO ÀXVVR

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WDOH SRWHQ]D PHFFDQLFD SHU IDU Vu FKH OD PDFFKLQD IULJRULIHUD IXQ]LRQL ULVSHWWDQGR O¶HQXQFLDWR

GL &ODXVLXV WDOH PDFFKLQD SUHOHYHUj TXLQGL LO ÀXVVR WHUPLFR

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