Examples of Chemical Reactions

In this book we will consider a variety of reactions that take place in the gaseous state, in liquids other than water (nonaqueous media), and in aqueous solutions. Let us consider a few examples before we move on to increase our understanding of chemical reactions and how we interpret equations that represent those reactions. 

Most of the time you might not be conscious of it, but chemical reactions are taking place in the atmosphere all the time. If the sky above you is not blue, though, or if there is an odor to the air around you, then you know that chemical reactions have taken place. 

For example, ground-level air pollution usually begins with the exhaust gases being emitted into the atmosphere from motor vehicles. The exhaust gases consist mostly of carbon dioxide (CO ) and water (H O), but they may contain some nitric oxide (NO). Catalytic converters are supposed to remove NO, and they mostly do, but air pollution does take place. 

Nitric oxide itself is a colorless gas, but in the atmosphere it is converted to nitrogen dioxide (NOj) by the following reaction  

If you have ever been in an urban environment in warm weather, you probably saw NO, a reddish-brown gas that lends a brownish haze to the sky if there is enough of it. From an airplane or a hilltop, a layer of brown-colored air is particularly conspicuous. NOj is also toxic, but it is not the real culprit in an air pollution episode. 

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There are numerous examples of chemical reactions consequent upon chemical groups which occur repeatedly along a chain. In some cases the reaction occurs randomly between adjacent pairs of groups such as in the reaction between aldehydes and polyvinyl alcohol and of zinc dust with polyvinyl chloride ... 

Consider the examples of some of the forms of chemical equations (and related representations) met in school and college (i.e. middle and senior high school) science and chemistiy classes that are shown in Table 4.1. For the purposes of this chapter half-equations (Example 11) and symbolic representations of processes such as ionisation (Example 10) will be included under the generic heading of chemical equations . Table 4.1 does not include examples of chemical reactions and reaction schemes that include stmctural formulae, as are commonly nsed in organic chemistiy. 

The knowledge was consolidated on further examples of chemical reactions (macro level, submicro level symbolic). 

Examples of chemical reactions have been presented and carried out in different types of HEX reactors. Applications such as oxidation, nitration, hydrosilylation, are still in progress in the industrial companies... 

In this chapter, we study the variation in the FF during asymmetric stretching and bending in ammonia, internal rotation in H202, and along the intrinsic reaction coordinate (IRC) of three prototypical examples of chemical reactions, viz., (1) a thermoneutral reaction, such as a symmetrical gas-phase SN2 type nucleophilic substitution ... 

We have seen many examples of chemical reactions involving enolate anions, and should now realize just how versatile they are in chemical synthesis (see Chapter 10). We have also seen several examples of how equivalent reactions are utilized in nature. For the triose phosphate isomerase mechanism above, we did not actually invoke a distinct enolate anion intermediate in the enolization process, but proposed that there was a smooth flow of electrons. For other reactions, we shall also need to consider whether enolate anions are actually involved, or whether a more favourable alternative exists. The aldol-type reaction... 

A. Examples of chemical reactions in drug biotransformation (hydrolysis)... 

With our first example of chemical reactions, we want to get acquainted with a very important type of reaction in organic chemistry, that is, with nucleophilic substitution at a saturated carbon atom. Since halogens are very common constituents of man-made organic chemicals, we consider their displacement by environmentally relevant nucleophiles. In these cases the halogen plays the role of the leaving group. 

For example, the standard synergetic approach [52-54] denies the possibility of any self-organization in a system with with two intermediate products if only the mono- and bimolecular reaction stages occur [49] it is known as the Hanusse, Tyson and Light theorem. We will question this conclusion, which in fact comes from the qualitative theory of non-linear differential equations where coefficients (reaction rates) are considered as constant values and show that these simplest reactions turn out to be complex enough to serve as a basic models for future studies of non-equilibrium processes, similar to the famous Ising model in statistical physics. Different kinds of auto-wave processes in the Lotka and Lotka-Volterra models which serve as the two simplest examples of chemical reactions will be analyzed in detail. We demonstrate the universal character of cooperative phenomena in the bimolecular reactions under study and show that it is reaction itself which produces all these effects. 

This paper outlines the basis for applying thermodynamic principles in studying the chemistry of natural water systems of all kinds, discusses the kinds of thermodynamic models available, and indicates some important limitations of such thermodynamic approaches. The general ideas will be illustrated by considering a few examples of chemical reactions of some interest in various kinds of natural water systems. 

Figure 1.1 Examples of chemical reactions, a) This truck s iron frame has rusted over time due to outdoor exposure, b) The chemical composition of this egg changes when it is dropped into a hot pan. c) Fall leaves change color because of the chemical reactions that occur within their veins.

All the fabulous success stories and the terrible disasters that can occur in kitchens around the world can be blamed on chemical reactions. Cakes are light and fluffy because the baking soda in the batter reacts with an acid to produce carbon dioxide, a gas. When sugar is heated, it turns into dark brown, gooey caramel. The cut surfaces of apples and bananas turn brown because they react with oxygen in the air. All of these are examples of chemical reactions in the kitchen. 

Some other examples of chemical reactions and their representation by chemical formulae are ... 

The aim of this section is to demonstrate how reaction calorimetry in combination with IR-ATR spectroscopy can be used for the determination of kinetic and thermodynamic parameters. Several examples of chemical reactions will be discussed, each highlighting a different aspect in the application of reaction calorimetry. The reactions considered are the hydrolysis of acetic anhydride, the sequential epoxidation of 2,5-di-ferf-butyl-l,4-benzoquinone and the hydrogenation of nitrobenzene. The results discussed in this section were obtained using a new calorimetric principle presented below. 

Synchronous processes represent the most demonstrative and unique example of chemical reaction ensembles, arranged in time and space. Interest in synchronous chemical reactions is also so much keener, because in biological systems many processes are synchronous. This means that biochemical reactions are arranged and performed in systems with molecular and permolecular structures, which is the chemist s pipe dream . Studies performed in recent decades have allowed the development of the interaction theory for synchronous chemical reactions at two levels—microscopic and macroscopic. Strictly speaking, parallel reactions may also be taken as synchronous reactions although proceeding simultaneously in the reaction system, they are characterized by the absence of any interaction between them. However, such synchronous reactions are trivial and of no special interest for chemistry. It is of much more importance when they interact and, therefore, induce oscillations in yields of synchronous reaction products. 

In fact, there are examples of chemical reaction in catalysis, which proceed on membranes not dividing the reaction zone into zones. They behave in the system as normal catalysts, e.g. obeying kinetic regularities of heterogeneous catalytic systems. 

Table 1 Examples of chemical reactions catalyzed by antibodies...

Standard methods and techniques are covered and examples of chemical reactions are provided to illustrate the applicability of a particular method/technique to specific chemical systems and to demonstrate the utility of the information obtained in deciphering the mechanism. It is not the purpose of this chapter to provide an in-depth review of the chemistry involved. 

Make flashcards that contain examples of chemical reactions. Quiz each other on reaction types by using the flashcards. Explain how you identified each type. 

This discussion will be mainly qualitative. We will begin with a classic example of chemical reactions directly related to the electron density distribution the electrophilic aromatic substitution reactions of the benzene derivatives aniline and phenol ... 

When a compound undergoes a reaction and maintains its molecular structure and thus its identity, the reaction is called a physical reaction. Melting, evaporation, dissolution, and rotation of polarized light are some examples of physical reactions. When a compound undergoes a reaction and changes its molecular structure to form a new compound, the reaction is called a chemical reaction. Combustion, metathesis, and redox are examples of chemical reactions. Chemical reactions can be represented by a chemical equation with the molecular formulae of the reactants on the left and the products on the right. 

You have already seen several examples of chemical reactions sugar and acid (Figure 3.1), aluminum and bromine (Figure 1, p. 2), and sodium and chlorine (Figure 1.9). 

There are many other examples of chemical reactions being induced by shearing stresses. A mechanism involving metallization seems plausible. Areas of application include photochemistry, degradation of polymers, friction and wear, mechanical alloying and cutting processes. 

It is quite likely that there might be numerous examples of chemical reactions which oscillate without any period thus forming condidates for exploded points. However, this remains to be verified. 

The heating of sugar, the reduction of metals from their ores and the cracking of petroleum molecules are all examples of chemical reactions. 

Biochemistry and are far from being meant as a comprehensive list of the numerous chemical reactions that have been used by chemists and biochemists to obtain substances in the pure state. More examples of chemical reactions used as aids in separation processes are dispersed throughout the book. Two such noteworthy examples are (i) Ion-exchange chromatography, and (ii) electrorefining which is purification by chemical reactions carried out with the help of an electric current. In the same context one is also reminded of the use of some chemical reactions for separation of inorganic ions mentioned in the previous chapter during discussion of Solvent Extraction. 

Table 11.8 lists some of the models that have been discussed in the literature [Shalhi 1993] in chronological order. The increasing model complexity with time is illustrated by Table 11.8 with gradual recognition of the importance of hydrodynamics, mass transfer and reaction kinetics. In some of the models no account of removal is taken, and indeed in some extreme examples of chemical reaction fouling, removal of a deposit once formed is indeed negligible. 

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