Reaction rate theory, Eyring

Reviews of reaction rate theory by Laidler and Wayne are very helpful. A classic book by Glasstone et al. is still an excellent introduction to the subject. Eyring et al." provide an advanced, detailed treatment of kinetic theory. 

Hie possibility that a particle with energy Jess than the barrier height can penetrate is a quantum-mechanical phenomenon known as the tunnel effect. A number of examples are known in physics and chemistry. The problem illustrated here with a rectangular barrier was used by Eyring to estimate the rates of chemical reactions. ft forms the basis of what is known as the absolute reaction-rate theory. Another, more recent example is the inversion of the ammonia molecule, which was exploited in the ammonia maser - the fbiemnner of the laser (see Section 9.4,1). 

The transition state theory provides a useful framework for correlating kinetic data and for codifying useful generalizations about the dynamic behavior of chemical systems. This theory is also known as the activated complex theory, the theory of absolute reaction rates, and Eyring s theory. This section introduces chemical engineers to the terminology, the basic aspects, and the limitations of the theory. 

According to Eyring s reaction-rate theory,90 the elementary bimolecular chemical reaction between reactant species A and B proceeds through a transition-state... 

The Arrhenius theory (above) was wholly empirical in terms of it derivation. A more rigorous, but related, form of the theory is that of Eyring (also called the theory of absolute reaction rates). The Eyring equation is... 

Detonation, Absolute Reaction Rate Theory of Eyring or Activated Complex Theory. See Absolute Rate Theory in Vol 1 of Encycl, p A4-R and in Cook (1958), p 134... 

Detonation, Activated Complex Theory or Transition State Theory. Same as Detonation, Absolute Reaction Rate of Eyring... 

Eyring absolute reaction rate theory see Absolute rate theory 1 A4 6 E508... 

According to the absolute reaction rate theory as first applied by Eyring et al. to electrode reactions [31]... 

The relation between the frequency v of local jumps, shear stress r, temperature T and macroscopic rate of creep e was well established by Eyring s reaction rate theory [41]. Let us consider that a number of vl0 thermally activated structural units attempt per unit time to cross a potential barrier Ur, the net flow v, of units that will succeed is then given by ... 

Transition-state theory or reaction-rate theory was extensively developed by H. Eyring and collaborators (Glasstone et al., 1941 Frost and Pearson, 1961). 

Bosse [48] proposed a new model to predict binary Maxwell-Stefan diffusion coefficients Dij, based on Eyrings absolute reaction rate theory [49]. A correlation from Vignes [50] which was shown to be valid only for ideal systems of similar-sized molecules without energy interactions [51] was extended with a Gibbs-excess energy term... 

The classical inversion mechanism is a thermally activated process 2>, activation energies being determined from the variation of inversion rates with temperature. The corresponding rates for passage over the barrier may be calculated from the absolute reaction rate theory 2>. The rate constant is given by the Eyring rate equation ... 

The next development of the chemical reaction rate theory was provided by Eyring [49-51], who suggested a more advanced model... 

As a result of the development of quantum mechanics, another theoretical approach to chemical reaction rates has been developed which gives a deeper understanding of the reaction process. It is known as the Absolute Reaction Rate Theory orthe Transition State Theory or, more commonly, as the Activated Complex Theory (ACT), developed by H. Eyring and M. Polanyi in 1935. According to ACT, the bimolecular reaction between two molecules A2 and B2 passes through the formation of the so-called activated complex which then decomposes to yield the product AB, as illustrated below ... 

As pointed out by Doolittle, the relationship between the viscosity of liquids and their free volume remained for a long time only an intuitive hypothesis though it described quite well numerous experimental results. A theoretical approach to the solution of the problem of the relationship between the viscosity of liquid and its free volume was generalized for the first time by Eyring [85] in terms of the absolute reaction rates theory. The formulas obtained by Eyring pointed to a qualitative relationship between viscosity and the ratio of the volume occupied by liquid molecules C to the volume occupied by holes through which molecules jump to the neighboring position ... 

More detailed expressions are available from absolute reaction rate theory (Pelzer and Wigner 1932 Evans and Polanyi 1935 Eyring 1935). This approach treats the forward and reverse reaction processes as crossings of molecular systems over a mountain pass on their potential energy surface. Systems at the pass are called activated complexes, denoted by t f... 

Eyring applied his reaction rate theory to viscosity and specifically modified it for H bonded fluids (626). However, he used it just to explain in a general way the viscosity of associated liquids, since the contributions. .. of van der Waals, dipole, and H bond forces, and especially of repulsive forces, are not known for any associated liquid. The state of affairs is not greatly different today. 

This paper deals with some aspects of the theory of photochemical reactions, and necessarily makes contact with the theory of unimolecular reactions and the theory of energy transfer. The indirect influence of Henry Eyring s work is manifest in much of what follows since, in part, we are concerned with the validity of the usual concepts of unimolecular reaction rate theory. 

I have not mentioned at all in this set of comments the fascinating new studies that relate orbital symmetries and reaction pathways these also have greatly increased our understanding of photochemical reactions. They are, however, concerned with aspects of reaction rate theory intrinsically different from those studied by Henry Eyring. For that reason the interested reader is referred to the literature. ... 

The first discussion of this problem, including a derivation of (9) by absolute reaction rate theory, was given by Eyring, Hirschfelder, and Taylor. ... 

Although the name Henry Eyring had come to my attention many times before the autumn of 1947, it was only then that my intimate association with him began. It lasted for six inspiring years. Before that time he had already won fame in his application of reaction-rate theory to a myriad of problems, including chemical reactions, biological processes, and viscosity. 

Henry Eyring s courses in statistical mechanics and reaction rate theory opened a new world to me when I took them in 1947-48 while a graduate student in physiology. My most vivid memories of these courses are the clarity of his lectures, his enthusiasm for his subject, and the insight he imparted into the behavior of matter at the molecular level. The brilliance of his lectures was emphasized when Henry was out of town and his post-doctoral students had to substitute for him they suffered in the inevitable comparison. 

The Eyring surface erosion model was applied together with the general absolute reaction rate theory to the rate of mass loss of meteors as they pass through the atmosphere. Atmospheric erosion of the heat shield of space vehicles upon reentry is a problem of great importance to which this theory is directly applicable. 

The values between brackets are calculated from Eyring s reaction rate theory in this calculation it was supposed ... 

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