The Nature of Chemical Reactions

Boo, H. K. (1994). A-level chemistry students conceptions and understandings of the nature of chemical reactions and approaches to learning of chemistry content. Unpublished Ph.D. thesis. University of London, London. 

The explanation of these findings was at that time never self-evident. In contrast to the other reactivity theories, which then existed and had already been well-established theoretically, the infant frontier-electron theory was short of solid physical ground, having suggested a possibility of the involvement of a new principle relating to the nature of chemical reactions. 

A comparison has been made of Platforming and of thermal reforming from the standpoint of yield-octane number relationships, product properties, hydrocarbon types, and with respect to the nature of chemical reactions responsible for improvement of octane number. Comparison is based on studies of thermal reforming in a commercial operation at a Pennsylvania refinery and in a pilot plant on a midcontinent naphtha and in pilot plants and laboratory Platforming on the same stocks. 

In addition to exploring the chemical identity of gases and the nature of chemical reactions, Joseph Gay-Lussac was one of the first balloonists. In one of his balloon flights to test hypotheses on the composition of air and the extent of Earths magnetic field, Gay-Lussac reached an altitude of7000 meters (23,000 feet). This record remained unbroken for the next 50 years. 

These relations reveal the nature of chemical reactions involved in formation of CBPCs, which include dissolution of oxides and acid phosphates, and their subsequent acid-base reaction to form ceramics. Therefore, the Gibbs free energy plays an important role in determining which reactions (and hence which components) are most suitable in forming ceramics. 

Comparing the terms plasma chemical vapor deposition and luminous chemical vapor deposition, the dilference exists in the meaning of plasma and luminous gas and its implications to the nature of chemical reactions that occur in the gas phase. Without referring the details of the difference, however, the process could be described either plasma polymerization (plasma CVD) or luminous CVD in all practical purposes. 

Water is highly unusual in the extent of its interactions with solutes, but even minimal solvent-solute interactions can play a major role in the nature of chemical reactions. To calculate pH during acid-base titrations in a nonaqueous solvent, we must consider not only the equilibria discussed in Chapter 3 but also reactions discussed in Sections 4-2, 4-3, and 4-4. 

AND SEEN HOW CHEMICAL KINETICS AND CHEMICAL EQUILIBRIUM CONCEPTS HELP US UNDERSTAND THE NATURE OF CHEMICAL REACTIONS. IT... 

Using an apparatus constructed on the same principles, Ott and Schmidt99 prepared carbon suboxide C302 by thermal decomposition of diacetyltartaric anhydride on a feebly glowing platinum catalyst — the nature of chemical reaction is obscure. 

Because it requires many possible variables, such as temperature, pressure, the nature of chemical reaction, and the character of the solid surface, and because it incorporates many constants which require experimental evaluation, the general mathematical model to estimate the product gas distribution for different levels of carbon conversion can become exceedingly complicated. Practical application of this model is particularly difficult when a choice has to be made between reaction mechanisms, each of which can generate complex functions with a sufficient number of arbitrary constants to fit any given experimental curve. The purpose of the work discussed in this paper was to study the influence of temperature and the partial pressure of hydrogen and steam on the rate of steam-hydrogen and coal char reactions based on the previous pilot plant data obtained at IGT (10, 11) and to develop a correlation to estimate the performance of a hydrogasification reactor in terms of its product gas distribution for different levels of carbon conversion. 

A self-consistent treatment and natural coupling between those methods are essential to reveal the nature of chemical reactions in solution. 

We have studied basic definitions in chemistry, and we have examined the properties of gases, liquids, solids, and solutions. We have discussed chemical bonding and intermolecular forces and seen how chemical kinetics and chemical equilibrium concepts help us understand the nature of chemical reactions. It is appropriate at this stage to apply our knowledge to the study of one extremely important system the atmosphere. Although Earth s atmosphere is fairly simple in composition, its chemistry is very complex and not fully understood. The chemical processes that take place in our atmosphere are induced by solar radiation, but they are intimately connected to natural events and human activities on Earth s surface. 

The nature of chemical reactions is the breaking of old bonds and the formation of new bonds. Molecular reaction dynamics is the study on how the old bonds are broken and how the new bonds are formed. In the past few decades, molecular reaction dynamics is an important field of physical chemistry and chemical physics. Its main task is to study elementary chemical reaction processes on the atomic scale and femtosecond (even attosecond) time scale. The in-depth study of this field offers important knowledge to atmospheric chemistry, interstellar chemistry, as well as combustion chemistry, and deepens our understanding of the essential nature of chemical reactions in nature. In the 1980s, the improvement of the crossed molecular beam technique [1] and femtosecond chemistry [2] enabled the molecular reaction dynamics to have a rapid development, and gradually mature. In the last ten years, the molecular reaction dynamics had a lot of progress and made a series of achievements, due to the many new technologies, the development, and innovation of new experimental methods, and advances in theory and computation [3]. 

An understanding of the nature of chemical reactions requires the details of the elementary-reaction steps in which, the molecules come together, rearrange, and leave as species that differ from the reactants. There are two descriptions that deal with the rates of chemical reactions. The collision theory considers the concept that the reaction of molecules can occur only as a result of collision of the reactant molecules. The transition-state theory focuses on the species that corresponds to the maximum-energy stage in the reaction process. This species is called the activated complex or transition state. The transition state, denoted by the symbol A for reaction (1), is a short-lived species, which is converted to C. The reader is referred to [1-10] for a thorough discussion of the energetics involved in chemical reactions. 

In the same period also the observation of time become important for the determination of the nature of chemical reactions. Time of decurrence was clearly contemplated for the... 

Fujimoto H, Katata M, Yamabe S, Fukui K (1972) An MO-theoretical interpretation of the nature of chemical reactions III. Bond interchange. Bull Chem Soc Jpn 45(5) 1320-1324... 

The collision theory is a useful one not only in the sense that it has provided insight into the nature of chemical reactions, but also because it is a theory that can be readily tested. The mark of a scientific theory is that it can be tested and falsified. So far, collision theory has been supported by experimental evidence, but if new data were produced that could not be explained using the collision theory then it would need to be modified or dismissed in favour of a new theory that did explain all the evidence. Currently collision theory is the best explanation of the experimental data produced so far (at this working level). It should be noted here that we have not begun to distinguish between elementary and complex, multi-step reactions. That discussion is developed in Chapter 16 with the introduction of the idea of the rate-determining step in a sequence of stages. This is an example of how the theory is modified to explain more complex situations. Note that unimolecular reactions are an apparent exception which require special treatment. 

When a system reaches thermodynamic equilibrium, however, its history is of no importance. Regardless of the path leading to equilibrium, the state of equilibrium can be described by general laws. In this chapter we shall first look at the nature of chemical reactions then we study the relation between entropy production and the rates of chemical reactions that drive the system to equilibrium. 

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