Chemical kinetics as part of physical chemistry in the XIXth century and at the beginning of the XXth century: Analysis of the origin and development of phenomenological kinetics
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Intern. Zs. f. Gesch. u. Ethik tier Naturwiss., Techn. u. IVied., 4 (1996): 19-30 0036-6978/96/010019-12 $ 1.50 + 0.20 9 1996 Birkhtiuser Verlag, Basel
Chemical Kinetics as Part of Physical Chemistry in the XIXth Century and at the Beginning of the XXth Century: Analysis of the Origin and Development of Phenomenological Kinetics
Viktor A. Kritsman
Dieser Artikel beruht auf meinem Vortrag fiber ,,Origin and Development of the Phenomenological Kinetics as an Important Pm't of Physical Chemistry: 19th-20th Centuries" auf dem XIXth Interna- tional Congress of History of Science (Zaragoza, Spain), 1993. In dieser Abhandlung wurden die Entstehang und Entwicklung der phgnomenologischen chemischen Kinetik vom 19. his zum Beginn des 20. Jahrhunderts aufgund der von mir frtiher entwickelten Methode der Erforschung des geschichtlichen Prozesses der Chemie analysiert. Die historische Analyse wurde mit den verschie- denen Reaktionsmodellen verkniipft, die den wichtigsten kinetischen Theorien als Grundlage gedient hatten. Es wurde auch eine neue Definition der ph~nomenologischen chemischen Kinetik vorge- schlagen. Sie wird als Lehre vonder Reaktionsgeschwindigkeit betrachtet und durch die Verwendung physikalischer Modelle der ldnetischen Gastheorie interpretiert.
At the beginning of the 1850s, the description of chemical reactions by means of formulae had clearly demonstrated the importance of the time factor for studying reactions. At this time chemists finally acknowledged the necessity of studying reaction rates. The development of chemical statics and dynamics in the 1850s- 1870s also stimulated the emergence of phenomenological chemical kinetics as an important part of physical chemistry in the 1880s I. The doctrine of reaction velocity and its interpretation on the basis of the kinetic theory of gases is called phenomenological chemical kinetics. In this doctrine, rates of reactions were studied and calculated mainly theoretically ("formally").
A hundred years later, chemical kinetics had become the theory that deter- mined to a large extent the nature and the trends of research in physical chemistry. Its concepts, laws, models and methods are widely applied now in various branches of science and technology which deal with the transformation of matter and energy by means of chemical reactions 2. This increased importance of chemical kinetics has attracted the attention of many researchers to the problems of its history and methodology from the t880s until now 3.
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Although historical studies have provided much information on factual details, several important matters concerning the development of chemical kinet- ics have not yet been investigated, among them:
- the concept of time in chemistry before the emergence ofphenomenoIogi- cal chemical kinetics in the 1880s;
- the existence of different models (physical, chemical, mathematical) ap- plied to the explanation of the process of chemical reaction; their origins and interaction;
- the transition from the model of "simple" reaction to the model of the reacting system, and the reasons why phenomenological kinetics was replaced by new theories in the 20th century.
In our analysis of the origin and development of phenomenological kinetics, we have used the principles of historical analysis and periodisation of chemical kinetics described above 4. My historical analysis of the origin and development of chemical kinetics is principally about the emergence of the system approach. Special attention is paid to different types of reaction models (see Fig. 1). On the basis of this approach, I identify four periods in the history of chemical kinetics (see Fig. 2). The first three are connected with the origin and development of phenomenological chemical kinetics. In short, the stages of this process can be formulated as follows.
Period I: Prehistory of chemical kinetics (up to the 1850s)
During the scientific revolution of the XVIIth century, chemists developed a view of a reaction as simple combination, dissolution and recombination of particles. These transformations were taken to be instantaneous. In the XVIIIth century this concept of the chemical reaction was implicitly formulated in various tables of chemical affinity, which summarized the results of the comparative studies of chemical processes by Antoine Lavoisier, Torbem Bergman and others. At the turn of the XIXth century, these tables of affinity were replaced by the analysis of states of equilibrium, which were understood as the result of a balance of the forces of affinity of direct and reverse reactions in chemical processes on an almost mechanical analogy (see Claude Louis Berthollet chemical statics (1800- 1803) 5 .
Some investigations at the end of this period had showed, however, that mechanical models of forces of affinity could not account for the pecularities of chemical transformations. For this purpose, several specific chemical models (signs, formulae) were developed.
Chemical Kinetics as Part of Physical Chemistry FORSCHUNG - RESEARCH
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Mechanical "force" models of reactions (R. Descartes, I. Newton, a.o. - Up to middle XVIJI c.). Analogy of mechanical and chemical processes (K. Wenzel, C. Berthollet, a.o. - Second half of the XVIII/beginning of the XIX cc.). Improving the static model of chemical equilibrium (J.L. Gay-Lussac, M. Chevreal, G. Rose - Up to 1850s). Transition from the static to the dynamic model of chemical transformation (L. Wilhelmy, M. Berthelot, C. Guldberg- 1850s-1870s). Studying the reaction rates, based on the model of the kinetic theory of gases (Collision of spheres, J.H. Van't Hoff, S. Arrhenius, W. Ostwald a.o. - 1880s-1890s). Further development of the theory of collisions (W.G. McLewis, C. Hinshelwood, I. Christi- arisen a.o. - 1910s-1930s). Formation and development of the transition state based on the physico-chemical model of the transition state-"activated complex" and used for the "kinetic description of different reactions (M. Polanyi, M. Evans, H. Eyring, K. Laidler, C. Hinshelwood, N.N. Semenov a.o. - 1930s-1990s). Compiling and studying the Tables of affinity (E. Geoffroy, I. Newton, T. Bergman, A. Lavoisier a.o. - 1700s-1770s). The use of symbols to describe transformation mechanisms (A. Lavoisier, W. Higgins, E. Fulham, N. Clemant a.o. - 1770s-1810s). The use of formula models to describe the mechanisms of complex reactions (H. Davy, J. Liebig a.o.- 1820s-1850s). Early attempts at finding the interrelation between the rates and mechanisms of reactions (A. Kekule, O. Laurent, A. Vernon Harcourt, W. Esson, N. Menshutkin a.o.- 1850s-1870s). Systematically combined physical and chemical models for the kinetic description of different reactions (W. Ostwald, R. Ltither, N.A. Shilov a.o. - 1890s-1900s). Study of simple and complex reactions (including chain reactions), the base of a new physico-chemical model (M. Bodenstein, W. Nernst, C. Hinshelwood, N.N. Semenov a.o. - 1910s-1930s).
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XVII C.-XVlII C. XlX C. XX C.
Fig.2. Formation and development of chemical kinetics (periodization) 1. Period I. Prehistory of chemical kinetics - up to 1850s. 2. Stage 1. Doctrine of "affinity" as the basis for studying reactions. Beginning of the concept
of time in chemistry: XVIII-be~nning of the XIXth century. 3. Stage 2. Creating the prerequisities of chemical kinetics: 1800s-1840s. 4. Period II. Emergence of basic concepts of chemical kinetics (1850s-1870s). 5. Period IlL The development of phenomenological chemical kinetics (1880s--1900s). 6. Stage 1. Elaborating the kinetic classification of simple reactions regarded as stages of
complex transformations: 1880s-1900s. 7. Stage 2. Studying the regularities of complex reactions: 1890s-1900s. 8. Period IV. Transformation of chemical kinetics into a science of the interrelation between the
rates and mechanisms of reactions: 1910s-1990s. 9. Stage 1. Investigations of the interrelation between the rates and the mechanisms of simple
and complex reactions: 1910s-middle 1930s. 10. Stage 2. Development of chemical kinetics as a science of the interrelation between the rates
and the mechanisms of the reactions: late 1930s-1990s.
Period II: Emergence of basic concepts of phenomenological chemical kinetics (1850s-1870s):
The understanding of chemical structure in the XIXth century (theory of chemical constitution before 1860) was closely connected with the development of the concept of the temporal continuity of chemical reactions (Nicola C16ment, Charles Desormes, Alexander Wil l iamson a.o.) 6 (see Fig.3). Thus the time factor came into consideration, leading later, mainly in XXth century, to the investiga-
tions of the rate and mechanisms of reactions and relations between them.
Chemical Kinetics as Part of Physical Chemistry FORSCI ' tUNG-RESEARCH
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Fig. 3. Main trends in the use of time to characterize the reactions: XVIII c.-1850s 1. First concepts of a multi-stage reaction. W. Higgins, 1789; E. Fulham, 1794. 2. Elaborating the first mechanisms of multi-stage catalytic reactions. 1790s- 1850s. D. Clement,
Ch. Desormes, H. Davy, W. Higgins, J. Liebig, A. Williamson. 3. Acceleration - indicator of reaction rate, 1840s. 4. Time - a function of the multi-stage nature of a process, 1850s, J. Liebig. 5. Separation of chemical dynamics from statics. 1850s, A. Williamson. 6. Application of mechanical analogies to estimate chemical affinity. 1770s, C. Wenzel. 7. Time - the major indicator of dynamics. 1850s, A. Williamson.
An important point was reached with the development of the concept of the limit of reversible reactions. This concept was widely discussed in the 1850s- 1870s (Williamson, Ludwig Wilhelmy, Marcelin Berthelot, Cato Guldberg, Peter Waage a.o.) (see Fig.4). 7 Around this time, the idea of reaction rate as a mathe- matical function of concentration was being developed.
Historians often say that Wilhelmy's study of the rate of the reaction of the catalytic inversion of sucrose (1850) was ignored by contemporary chemists. 8 True, there were relatively few citations of his paper, but there are still good grounds for believing that it was read and that it influenced the subsequent development of this theory and contributed to the transition from static to dynamic models of Chemical equilibrium.
In 1861-1863 the Russian chemist Dmitriy Mendelee v stated in his influential textbook on organic chemistry that without the study of reaction rates one could not understand chemical processes (especially complex reactions of organic compounds) 9.
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FORSCHUNG - RESEARCH Viktor A. Kritsman
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Fig. 4. Formation of concepts of the conditions of chemical equilibrium reactions: 1800s-1870s 1. "Chemical statics", 1801-1803, C. Berthollet. 2. Experimental study of equilibrium reactions of the exchange of salts. 1840s-1850s, R.
Bunsen, H. Debus, J. Malaguti, M. Margerittes, D. Gladstone. 3. Formation of the concept of dynamic equilibrium and the derivation of the principal postulate
of chemical kinetics. 1870s, J.H. Van't Hoff, C. Guldberg, P. Waage. 4. Electrochemical theories of atTmity. 1810s-1830s, J. Berzelius, H. Davy, M. Faraday. 5. Analogy between physical and chemical processes, 1850s-1870s, R. Clausius, A. Sainte-
Claire Deville, L. Pfaundler, A. Horstman, D.I. Mendeleev. 6. Formulation of the law of mass action, based on mechanical models of reversible reactions.
1860s-1870s, M. Berthelot, L. Pean de Sainte Gilles, C. Guldberg, P. Waage, J.H. Van't Hoff.
A new understanding of the mechanisms of chemical reactions was achieved in the middle of the XIXth century with the development of the concept of intermediate atonlic group, which is produced in the course of a reaction and, depending on the conditions of the process, can be transformed in different ways, resulting in different final products (A. Laurent, A. Kekule). This model, which had developed from the earlier ideas of J. Dumas, Ch. Gerhard and others, found a more exact formulation in the XXth century in the theory of transition state or the theory of absolute reaction rates.
A combination of physical, chemical and mathematical models was used in a series of investigations of chemical dynamics, in particular in the study of the complexity of chemical reactions in the 1860s by Berthelot and Leon Pean de Saint-Gilles, Guldberg and Waage, August G. Vernon Harcourt and William Esson (see Fig. 5). 10
Chemical Kinetics as Part of Physical Chemistry FORSCHUNG - RESEARCH
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Fig. 5. Origin of the fundamentals of chemical dynamics: 1850s-1870s. 1. Modelling the "elementary act" reactions allowing the redistribution of atoms during the
formation of a new atomic associate in the reaction. 1850s, R. Bunsen, H. Roscoe, A. Laurent, A. Kekule.
2. Principles of the theories of chemical structure and of intermediate compounds formed during reactions. 1850s-1870s, A. Kekule, A.M. Butlerov, V.V. Markovnikov.
3. Mechanisms of complex reactions, based on formula models. 1850s-1870s, J. Liebig, A. Williamson, M. Berthelot.
4. Principles of chemical affinity and the kinetic concepts in the study of the structural-kinetic regularities. First stage- late 1870s, N.A. Menshutkin.
5. Verification of the major chemical notions in studies of reactions. 1850s-1860s. A. Kekule, S. Cannizzaro a.o.
6. The study of the main kinetic regularities of complex reactions. 1860s, A. Vernon Harcourt, W. Esson.
7. Consideration of kinetic characteristics in identifying the individual elements of a kinetic system. 1850s, L. Wilhelmy.
8. Distinction between the regions of chemical statics and dynamics. 1850s, A. Williamson. 9. Establishment of the main principles of chemical kinetics. 1880s Van't Hoff, S. Arrhenius. 10. Showing the dynamic aspect of chemical statics when analyzing formula models. 1850s,
Especially important for understanding the reaction system and its kinetic description were a series of publications by the chemist Vernon Harcourt and the mathematician and chemist Esson in 1866-1867.
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Period IH: The development of phenomenological chemical kinetics as part of physical chemistry (1880s-1900s):
The chief founders of phenomenological chemical kinetics, in the 1880s, Jacobus Henricus Van't Hoff and Svante Arrhenius, chose as the fundamental subject of s...