Notional Concept

As far as this section is concerned, thermal aspects of the FRRPP process are of most interest, based on the manner at which it was able to store the exotherm locally and apparently able to release it to temperatures much higher than the adiabatic temperature rise in a coherent fashion (Cases 1-2) or catastrophically (Case 3) in micro-, meso-, and macroscales. The following case studies detail such behavior. 

1 Case 1 - Pressure Control Stirred-Tank Batch Reactor 

Reagent grade ether and styrene monomer were rid of dissolved gases by vacuum freeze-thaw cycles. The ether was distilled, while the styrene was used as is. Thus, styrene still contained nonvolatile inhibitor. The reactor was initially charged with 1 ml styrene, 100 ml ether, and AIBN (equivalent to 0.3 wt% in the system). The setpoint pressure in the reactor was slowly increased and the reactor temperature was recorded. 

Time (min s) Reactor temp. (°C) Init.-free temp. (°C) Pressure (psig) Comment(s) 

A detailed look at the temperature readings in Table 2.2.1 shows that higher temperature flashes were also obtained. For example, when the temperature was generally at 100°C, readings of 102 and 104°C can be seen momentarily from the digital display. 

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A possible reason for carrying out an experiment and analyzing the data is to test one notion, concept, model, hypothesis, or theory, or else possibly to select from among several competing theories. If the data do not coniform to what is anticipated by some particular theory, then its validity is challenged. In such a circumstance, one may devise a new notion, concept, or theory to better fit the data, or possibly reject one concept in favor of another. Whatever new idea emerges is then tested in still further experiments. 

In this theory, the fundamental notion is the concept of beam introduced similarly to that ft om the geometrical optics. The faces of the discontinuity will reflect all the electromagnetic beams due to the zero conductivity of the air filling the discontinuity The edge of the discontinuity will diffract the incident beam similarly to the Fresnel diffraction in optics. 

To extract infomiation from the wavefimction about properties other than the probability density, additional postulates are needed. All of these rely upon the mathematical concepts of operators, eigenvalues and eigenfiinctions. An extensive discussion of these important elements of the fomialism of quantum mechanics is precluded by space limitations. For fiirther details, the reader is referred to the reading list supplied at the end of this chapter. In quantum mechanics, the classical notions of position, momentum, energy etc are replaced by mathematical operators that act upon the wavefunction to provide infomiation about the system. The third postulate relates to certain properties of these operators ... 

Equation (A2.1.1) is essentially an expression of the concept of thermal equilibrium. Note, however, that, in this fominlation, this concept precedes the notion of temperature. 

The above argument shows that complete overlap of coil domains is improbable for large n and hence gives plausibility to the excluded volume concept as applied to random coils. More importantly, however, it introduces the notion that coil interpenetration must be discussed in terms of probability. For hard spheres the probability of interpenetration is zero, but for random coils the boundaries of the domain are softer and the probability for interpenetration must be analyzed in more detail. One method for doing this will be discussed in the next section. Before turning to this, however, we note that the Flory-Huggins theory can also be used to yield a value for the second virial coefficient. 

The simplest, qualitative, theoretical understanding of the nature of oxirene is provided by Breslow s concept of antiaromaticity. Whatever criticisms may be levelled at this notion (78JA6920), it does correctly predict that oxirene should be unusually unstable. 

A particularly useful concept in synthesizing MENs is the notion of corresponding composition scales. It is a tool for incorporating thennodynamic constraints... 

To deal with circumstances such as the bonding in ozone, the notion of resonance between Lewis structures was developed. According to the resonance concept, when more than one Lewis structure may be written for a molecule, a single structure is insufficient to describe it. Rather, the true structure has an electron distribution that is a hybrid of all the possible Lewis structures that can be written for the molecule. In the case of ozone, two equivalent Lewis structures may be written. We use a double-headed aiTow to represent resonance between these two Lewis structures. 

Although time as a physical or philosophical concept is an extremely subtle quantity, in chemical kinetics we adopt a fairly primitive notion of time as a linear fourth dimension (the first three being spatial dimensions) whose initial value (t = 0) can be set by the experimenter (for example, by mixing two reactant solutions) and whose extent is accurately measurable in standard units. The time dimension persists as a variable until the experimenter stops observing the reaction, or until... 

Accident Proneness. Tlie old notion that certain people are accident-prone has been difficult to establish as fact. A more acceptable concept may be "accident liability," which can be related to factors tliat often are temporary and do not depend primarily on persoiuality traits, such as w ork situation or stress. 

Another important concept is the notion of stabilization by means of coordination, A classic example is the. stabilization of the fugitive species cyclobutadiene, C4H4I by coordination to (Fe(CO)3l (p. 936). As the C atom is isoclectronic with (BH], so (C4H4] is isoelectronic with the borane fragment (BaH which is similarly stabilized by coordination to (Fe(CO)3l or the isoelectronic (Cofr/ -CsHs)) (see Panel on p. 174), Indeed it is a general feature of metallaboranc chemistry that such clusters are often much more stable than are the parent boranes themselves. 

Vorstelltmg,/. conception, idea, notion representation, performance introduction review (of troop.s remonstrance. Vorstellungsfahig wcit, /. conceptual (or imaginative) power. 

Viewing things from the perspective of his physical theory of contact electricity, Volta was intrigued by the apparently endless power of the battery to keep the electric fluid in motion without the mechanical actions needed to operate the classical, friction, electrostatic machine, and the electrophorus. He called his batteiy alternately the artificial electric organ, in homage to the torpedo fish that had supplied the idea, and the electromotive apparatus, alluding to the perpetual motion (his words) of the electric fluid achieved by the machine. To explain that motion Volta relied, rather than on the concepts of energy available around 1800, on his own notion of electric tension. He occasionally defined tension as the effort each point of an electrified body makes to get rid of its electricity but above all he confidently and consistently measured it with the electrometer. 

The example demonstrates that the concepts in chemistry rely heavily on notions from group theory, specifically the concept, introduced in Sec. 11, of the equivalence of configurations with respect to a permutation group. The cycle index and the main theorem of Sec. 16 play a role. 

Closely related to the concept of chirality, and particularly important in biological chemistry, is the notion of prochirality. A molecule is said to be prochiral if can be converted from achiral to chiral in a single chemical step. For instance, an unsymmetrical ketone like 2-butanone is prochiral because it can be converted to the chiral alcohol 2-butanol by addition of hydrogen, as we ll see in Section 17.4. 

What I hope to have added to the discussion has been a philosophical reflection on the nature of the concept of element and in particular an emphasis on elements in the sense of basic substances rather than just simple substances. The view of elements as basic substances, is one with a long history. The term is due to Fritz Paneth, the prominent twentieth century radio-chemist. This sense of the term element refers to the underlying reality that supports element-hood or is prior to the more familiar sense of an element as a simple substance. Elements as basic substances are said to have no properties as such although they act as the bearers of properties. I suppose one can think of it as a substratum for the elements. Moreover, as Paneth and before him Mendeleev among others stressed, it is elements as basic substances rather than as simple substances that are summarized by the periodic table of the elements. This notion can easily be appreciated when it is realized that carbon, for example, occurs in three main allotropes of diamond, graphite and buckminsterfullenes. But the element carbon, which takes its place in the periodic system, is none of these three simple substances but the more abstract concept of carbon as a basic substance. 

This is a crudal and frequently overlooked point about electronic configurations. They are far from being based in quantum mechanics it is precisely this theory that shows them to be an inadequate concept The notion that electron orbits and configurations really exist or "refer" is a relic of the old quantum theory and of Pauli s introduction of the exclusion prind-ple in its original and now strictly incorrect... 

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