69:
chemical actions under ordinary conditions, it is subject to numerous exceptions, and cannot therefore be taken (as its authors originally intended) as a secure basis for theoretical reasoning on the connection between thermal effect and chemical affinity. The existence of reactions which are reversible on slight alteration of conditions at once invalidates the principle, for if the action proceeding in one direction evolves heat, it must absorb heat when proceeding in the reverse direction. As the principle was abandoned even by its authors, it is now only of historical importance, although for many years it exerted considerable influence on thermochemical research.
197:
158:: “as motion was explained by the Newtonian concept of force, chemists wanted a similar concept of ‘driving force’ for chemical change? Why do chemical reactions occur, and why do they stop at certain points? Chemists called the ‘force’ that caused chemical reactions affinity, but it lacked a clear definition.
68:
Berthelot independently enunciated a generalization (commonly known as
Berthelot's Third Principle, or Principle of Maximum Work), which may be briefly stated as: every pure chemical reaction is accompanied by evolution of heat. Whilst this principle is undoubtedly applicable to the great majority of
217:
and does not suffer dissipation due to friction or heat exchanges. A simple example would be a frictionless spring, or a weight on a pulley in a gravitational field. Suppose further, that we thermally connect the primary system to a third system, a "reversible heat source". A reversible heat source
212:
unified all of this in his 300-page "On the
Equilibrium of Heterogeneous Substances". Suppose, for example, we have a general thermodynamic system, called the "primary" system and that we mechanically connect it to a "reversible work source". A reversible work source is a system which, when it does
218:
may be thought of as a heat source in which all transformations are reversible. For such a source, the heat energy δQ added will be equal to the temperature of the source (T) times the increase in its entropy. (If it were an irreversible heat source, the entropy increase would be larger than δQ/T)
184:. In 1875, after quantifying the heats of reaction for a large number of compounds, Berthelot proposed the “principle of maximum work” in which all chemical changes occurring without intervention of outside energy tend toward the production of bodies or of a system of bodies which liberate
165:, called the “Newtonian hypothesis”, which stated that light and heat are forms of matter attracted or repelled by other forms of matter, with forces analogous to gravitation or to chemical affinity.
52:, in a more accurate form. Berthelot's version was essentially: "every pure chemical reaction is accompanied by evolution of heat." (and that this yields the maximum amount of work). The effects of
574:
506:
815:
666:
200:
Thermodynamic systems in the maximum work theorem. dU is the energy lost to the reversible heat system as heat energy δQ and to the reversible work system as work δW.
135:
is essentially the energy of a chemical reaction "free" or available to do external work. Historically, the "free energy" is a more advanced and accurate replacement for the
617:
380:
313:
729:
417:
350:
759:
706:
253:
283:
444:
820:
When the primary system is reversible, the equality will hold and the amount of work delivered will be a maximum. Note that this will hold for
208:
in the 1850s and 60s, heats of reaction and the work associated with these processes were given a more accurate mathematical basis. In 1876,
102:
56:, however, showed this version to be incorrect. This was rectified, in thermodynamics, by incorporating the concept of
846:
870:
112:
901:
517:
466:
841:
767:
205:
628:
132:
97:
91:
and others to follow, the work principle was found to be a particular case of a more general statement:
161:
During the entire 18th century, the dominant view in regard to heat and light was that put forward by
169:
73:
37:
81:
33:
17:
585:
361:
294:
36:
produced there from. The principle was developed in approximate form in 1875 by French chemist
711:
391:
324:
177:
144:
140:
128:
77:
25:
734:
681:
181:
231:
851:
264:
148:
136:
53:
41:
428:
111:
The principle of work was a precursor to the development of the thermodynamic concept of
173:
155:
124:
49:
895:
209:
88:
45:
162:
100:
between the same initial and final state, the delivery of work is a maximum for a
213:
work, or has work done to it, does not change its entropy. It is therefore not a
214:
196:
80:
will tend to yield the maximum amount of chemical energy in the form of
57:
143:” used by chemists of olden days to describe the “force” that caused
195:
185:
29:
384:
The gain in internal energy of the reversible heat source
317:
The gain in internal energy of the reversible work source
154:
According to
Nobelist and chemical engineering professor
824: reversible system which has the same values of
44:, and then in 1876 by American mathematical physicist
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737:
714:
684:
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520:
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431:
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24:
was a postulate concerning the relationship between
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753:
723:
700:
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611:
568:
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438:
421:The gain in entropy of the reversible heat source
411:
374:
354:The gain in entropy of the reversible work source
344:
307:
277:
257:The loss of internal energy by the primary system
247:
72:Thus, to summarize, in 1875 by the French chemist
147:. The term dates back to at least the time of
94:
448:The temperature of the reversible heat source
8:
287:The gain in entropy of the primary system
769:
745:
736:
713:
692:
683:
657:
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468:
456:We may now make the following statements
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569:{\displaystyle dS+dS_{h}+dS_{w}\geq 0\,}
168:In the 19th century, the French chemist
882:Source: Ilya Prigogine's 1998 textbook
863:
501:{\displaystyle -dU=\delta Q+\delta W\,}
87:In 1876, however, through the works of
810:{\displaystyle \delta W\leq -(dU-TdS)}
204:With the development of the first two
7:
661:{\displaystyle \delta Q=TdS_{h}\,}
14:
578:(Second law of thermodynamics)
804:
783:
761:gives the following equation:
510:(First law of thermodynamics)
1:
32:evolution, and the potential
84:as the reaction progresses.
847:Thomsen-Berthelot principle
918:
612:{\displaystyle dS_{w}=0\,}
375:{\displaystyle \delta Q\,}
308:{\displaystyle \delta W\,}
176:had attempted to quantify
670:(Reversible heat source)
621:(Reversible work source)
22:principle of maximum work
724:{\displaystyle \delta Q}
412:{\displaystyle dS_{h}\,}
345:{\displaystyle dS_{w}\,}
871:Encyclopædia Britannica
842:Chemical thermodynamics
172:and the Danish chemist
98:thermodynamic processes
811:
755:
754:{\displaystyle dS_{h}}
725:
702:
701:{\displaystyle dS_{w}}
662:
613:
570:
502:
440:
413:
376:
346:
309:
279:
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206:laws of thermodynamics
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884:Modern Thermodynamics
812:
756:
726:
703:
663:
614:
571:
503:
441:
414:
377:
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250:
248:{\displaystyle -dU\,}
199:
133:Helmholtz free energy
768:
735:
712:
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629:
586:
518:
467:
429:
392:
362:
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278:{\displaystyle dS\,}
265:
232:
439:{\displaystyle T\,}
170:Marcellin Berthelot
74:Marcellin Berthelot
38:Marcellin Berthelot
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145:chemical reactions
78:chemical reactions
76:which stated that
48:, in the field of
40:, in the field of
26:chemical reactions
18:history of science
674:
673:
452:
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182:heats of reaction
178:chemical affinity
129:Gibbs free energy
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902:Thermochemistry
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852:Thermochemistry
838:
766:
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149:Albertus Magnus
137:thermochemistry
121:
119:Thermochemistry
109:
66:
54:irreversibility
42:thermochemistry
12:
11:
5:
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259:
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193:
192:Thermodynamics
190:
174:Julius Thomsen
156:Ilya Prigogine
125:thermodynamics
120:
117:
93:
65:
62:
50:thermodynamics
13:
10:
9:
6:
4:
3:
2:
914:
903:
900:
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848:
845:
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839:
835:
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831:
827:
823:
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786:
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771:
764:
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762:
746:
742:
738:
718:
715:
693:
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669:
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582:
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546:
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524:
521:
514:
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494:
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457:
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403:
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368:
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336:
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328:
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271:
268:
261:
260:
256:
241:
238:
235:
228:
227:
224:
223:
222:
219:
216:
211:
210:Willard Gibbs
207:
198:
191:
189:
187:
183:
179:
175:
171:
166:
164:
159:
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150:
146:
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138:
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126:
118:
116:
114:
107:
105:
104:
99:
92:
90:
89:Willard Gibbs
85:
83:
79:
75:
70:
63:
61:
59:
55:
51:
47:
46:Willard Gibbs
43:
39:
35:
31:
27:
23:
19:
883:
878:
866:
829:
825:
821:
819:
678:Eliminating
677:
455:
220:
203:
167:
163:Isaac Newton
160:
153:
122:
110:
101:
95:
86:
71:
67:
21:
15:
828: and
215:heat engine
113:free energy
858:References
103:reversible
793:−
781:−
778:≤
772:δ
716:δ
633:δ
560:≥
492:δ
483:δ
471:−
366:δ
299:δ
236:−
151:in 1250.
896:Category
836:See also
832: .
221:Define:
141:affinity
106:process.
96:For all
64:Overview
58:entropy
16:In the
731:, and
180:using
139:term “
127:, the
20:, the
873:1911
186:heat
82:work
34:work
30:heat
822:any
131:or
123:In
898::
830:dS
826:dU
708:,
188:.
115:.
60:.
28:,
805:)
802:S
799:d
796:T
790:U
787:d
784:(
775:W
747:h
743:S
739:d
719:Q
694:w
690:S
686:d
653:h
649:S
645:d
642:T
639:=
636:Q
606:0
603:=
598:w
594:S
590:d
563:0
555:w
551:S
547:d
544:+
539:h
535:S
531:d
528:+
525:S
522:d
495:W
489:+
486:Q
480:=
477:U
474:d
433:T
404:h
400:S
396:d
369:Q
337:w
333:S
329:d
302:W
272:S
269:d
242:U
239:d
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