Chemical equilibrium historical development

Historically, the state of reaction at chemical equilibrium was evaluated for fairly simple reactions, with only a few species, from the "Law of Mass Action. 1 In recent years, high-temperature reactions, including many possible species (as many as 20 or more), have become of interest and newer techniques suitable for numerical solution on high-speed digital computers have been developed.2 Initially, we will discuss chemical equilibrium from the vantage point of the "Law of Mass Action." It states that the rate at which a chemical reaction proceeds is proportional to the "active" masses of the reacting substances. The active mass for a mixture of ideal gases is the number density of each react-... 

The chapter starts with a brief introduction on the historical development of chemical equilibrium. On the basis of this historical analysis, the ways in which chemical equilibrium has been, and is, taught in curricula for secondary and higher education is then addressed. This curricular analysis provides a framework for the discussion of the teaching and learning of chemical equilibrium. A review is presented of learning difficulties associated with chemical equilibrium, followed by an overview of teaching... 

The historical development of chemical equilibrium has been described in several reviews (e.g., Berger, 1997 Laidler, 1985 Lindauer, 1962 Lund, 1965, 1968). The concept of chemical equilibrium was introduced in the 1860s in the context of empirical studies of incomplete and reversible chemical conversions. Explanations for these phenomena were formulated on the basis of two essentially different theoretical perspectives, a kinetic framework and a thermodynamic framework. 

The two main developments in science that initiated industrial catalysis were the discoveries of catalytic hydrogenation by Paul Sabatier and the ammonia synthesis by Fritz Haber, which built upon the chemical equilibrium thermodynamics of Jacobus van t Hoff and the rate equation of Svante Arrhenius. Many processes, often based on catalytic hydrogenation, followed. Section 1.2 gives a historic review of the early developments in catalysis. Because of its pivotal role in the initiation of industrial catalysis, we devote an entire section to the development of the ammonia synthesis. 

In this contribution, we describe and illustrate the latest generalizations and developments[1]-[3] of a theory of recent formulation[4]-[6] for the study of chemical reactions in solution. This theory combines the powerful interpretive framework of Valence Bond (VB) theory [7] — so well known to chemists — with a dielectric continuum description of the solvent. The latter includes the quantization of the solvent electronic polarization[5, 6] and also accounts for nonequilibrium solvation effects. Compared to earlier, related efforts[4]-[6], [8]-[10], the theory [l]-[3] includes the boundary conditions on the solute cavity in a fashion related to that of Tomasi[ll] for equilibrium problems, and can be applied to reaction systems which require more than two VB states for their description, namely bimolecular Sjy2 reactions ],[8](b),[12],[13] X + RY XR + Y, acid ionizations[8](a),[14] HA +B —> A + HB+, and Menschutkin reactions[7](b), among other reactions. Compared to the various reaction field theories in use[ll],[15]-[21] (some of which are discussed in the present volume), the theory is distinguished by its quantization of the solvent electronic polarization (which in general leads to deviations from a Self-consistent limiting behavior), the inclusion of nonequilibrium solvation — so important for chemical reactions, and the VB perspective. Further historical perspective and discussion of connections to other work may be found in Ref.[l],... 

In treating the various topics in this book the particular method employed has been determined in each case by considerations of simplicity, usefulness and logical development. In some instances the classical, historical approach has been preferred, but in others the discussion follows more modern lines. Whenever feasible the generalized procedures, involving reduced temperatures and pressures, which have been evolved in recent years chiefly by chemical engineers, are introduced. As regards statistical methods, the author feels that the time has come for them to take then-place as an essential part of chemical thermodynamics. Consequently, the applications of partition functions to the determination of heat capacities, entropies, free energies, equilibrium constants, etc., have been introduced into the text in the appropriate places where it is hoped their value will be appreciated. 

The theory and conditions for phase equilibrium are well established. If more than one phase is present, then the chemical potential of a component is the same in all phases present. As chemical potential is linked functionally to the concepts of fugacity and activity, models for phase behavior prediction and correlation based on chemical potentials, fugacities, and activities have been developed. Historically, phase equilibrium calculations for hydrocarbon mixtures have been fragmented with liquid-vapor, liquid-liquid, and other phase equilibrium calculations, subject to separate and diverse treatments depending on the temperature, pressure, and component properties. Many of these methods and approaches arose to meet specific needs in the chemical process industries. Poling, Prausnitz,... 

In this chapter I will try to explain why the creation of the Dutch chemical society occurred relatively late, and why it took on a hybrid character from the start. We will show that the founding of the NCV was the result of a carefully negotiated equilibrium between different groups of chemists, and also that initial opposition within academic circles had to be overcome. In order to understand these peculiarities of the Dutch case, it is important to first tell more about the institutional and social development of chemistry in the Netherlands up to 1903. In the course of this historical sketch the mutual relations and conflicts between the different groups of chemical practitioners will become clear, and also why the NCV was not founded earlier. 

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