The Nature of Chemical Interaction

More interesting from a fundamental point of view is the observation that the efficiency of poisoning depends also on the physical structure of the deposited impurity this is in turn governed by the nature of chemical interaction between the impurity and the electrode surface. In other words, a different mechanism of deposition may result in a structure of the deposit which does not inhibit the active surface substantially. Thus, in the case of Pt electrodes, it has been observed that if the impurity content is around 14 ppm Fe, the cathode may even be activated since small crystallites of iron are formed [167]. [Pg.16]

The above discussion points to the need for more detailed studies of stereochemical patterns and emphasizes the importance of such investigations in developing concepts of the nature of chemical interactions in the molecule. [Pg.65]

In the following section, the nature of chemical interactions between an ionic liquid and a transition metal catalyst is systematically developed according to the role of the ionic liquid in the different systems. [Pg.377]

An investigation of the nature of chemical interaction based on these criteria does not claim to give a full account of the problem in question however, when 2q>plied to A -c ... [Pg.98]

Up until now we have discussed the general methods for computing the cluster wavefunctions we now consider how the wavefunctions can be analyzed to obtain insights into the nature of chemical interactions at surfaces. In the introduction, we pointed out that the most commonly used method of analysis is the Mulliken population analysis and that this method of analysis may give misleading results. One alternative to a population analysis to get information about the charge associated with a given atom is the orbital projection approach. Here, one takes an atomic or molecular orbital, projection operator, P(( ) = spin orbital. The expectation value of P(v>) taken with respect to the cluster wavefunction provides a measure of the extent to which

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The nature of chemical coagulants are such that the macrofloc may possess certain charges for example lime (CaO), alum (A1203) and flocculating polyvalent cations cany positive charges, which interact with proteins. The interactions are simply illustrated in Figure 7.6. [Pg.179]

Methyl rotors pose relatively simple, fundamental questions about the nature of noncovalent interactions within molecules. The discovery in the late 1930s1 of the 1025 cm-1 potential energy barrier to internal rotation in ethane was surprising, since no covalent chemical bonds are formed or broken as methyl rotates. By now it is clear that the methyl torsional potential depends sensitively on the local chemical environment. The barrier is 690 cm-1 in propene,2 comparable to ethane,... [Pg.158]

Why did he think this was so One answer is that alkanes are available as raw material for the chemical industry, and new reactions by which they can be converted into functionally substituted organic compounds are likely to be of considerable interest to the industrial chemist. A second answer is that the nature of any interaction between an alkane and a transition metal must be quite different from that of other hydrocarbons (i.e., alkenes, alkynes, and aromatic compounds) having 7r-electrons that can play a dominant role. [Pg.148]

Experimental design does not explain the nature of any interaction, as this is a chemical task, but it provides helpful suggestions to explain it. Fairly often,... [Pg.60]

In this Sect, we discuss 1H, 19F and nB NMR studies of BF3 NH2C2H5 and BF3 NHC5H10 complexes, with principal emphasis on the former. We present the chemical composition of commercial BF3 amine complexes, their thermal stability in the solid state and in solution, the effect of moisture and heat upon their composition, the nature of their interaction with the epoxide and amine components utilized in TGDDM-DDS commercial prepregs, the composition of BF3 amine complexes in commercial prepregs, their thermal stability in the prepregs, and the chemical structure of the predominant catalytic species of the cure reactions of the prepreg. [Pg.8]

These level splittings are the essential features that determine the type of chemical interaction, i.e., 2c-le, 2c-2e or 2c-3e bond. However, as discussed in the preceding section, there are not many examples in which these bonds occur in such a pure state. Archetypal representatives of these bonding modes (e.g.,, H2, HeH) are in fact rather atypical for chemical bonds in general. In nearly all other cases, we have to deal with mono- or polyatomic fragments, carrying additional electrons in other orbitals. These electrons will interfere with and affect the nature of the primary frontier orbital interactions. Here we focus on the nature of the electron pair bond and how this bond can be influenced by Pauli repulsion effects due to other fragment orbitals such as lone pairs.54 72... [Pg.34]

Soft X-ray Imaging. The nature of their interaction with matter makes soft X-rays ideal for imaging the interior structure of inorganic nanoscopic systems and biological cells. Consequently, soft X-ray microscopy has been most widely applied to chemical imaging in the fields of cell biology, environmental science, soft matter and polymers, and nanomagnetism. [Pg.112]

Z. Czyznikowska, R. Zalesny, P. Cysewski, Quantum chemical study of the nature of stacking interactions of 2-oxo-adenine with native B-DNA purine bases. Pol. J. Chem. 82, 2269-2279 (2008)... [Pg.398]

A catalyst surface may be assumed to be characterized by specific poisoning if the number of adsorption sites, the strength (or the strength distribution) of the adsorbate-catalyst interaction, and the nature of this interaction as well as the chemical nature of the adsorbed species can be determined. All three properties are equally important to characterize fully, i. e., qualitatively and quantitatively, a catalyst surface. The number of adsorption sites may be determined from the adsorbed amount of poison as measured by conventional techniques, whereas thermoanalytical methods have to be applied for a quantitative characterization of the adsorption bond strength. Spectroscopic methods will be most suitable for studies of the chemical nature of the adsorbed species and the nature of the adsorbate-surface interaction. [Pg.195]

T o identify the nature of predominant interactions at interfaces between non-reactive metal M and ionocovalent oxide AO, different attempts have been made to correlate the energetic properties of interfaces (work of adhesion, work of immersion) to the energy of formation of M oxide or other quantities characteristic of the contacting phases, such as the surface energy of the metal or the gap energy of the ceramic. Any successful correlation between an energetic quantity of interfaces and the formation energy or enthalpy of MO oxide indicates the occurrence of a chemical interaction between M and AO at the interface, even... [Pg.207]

In this case the two systems evidently behave independently. Situations like this are fairly common in chemistry, generally associated with an approach to the classical limit in which the quantum potential becomes negligible and non-local interactions insignificant. Although the basic law therefore refers inseparably to the whole universe, it tends to fragment into numerous independent parts, each constituted of further sub-units that are non-locally connected internally. The key to this fragmentation is the lack (or nature) of chemical interaction between sub-units, which can be treated in the traditional way. [Pg.77]

Chemical behaviour depends on chemical potential and electromagnetic interaction. Both of these factors depend on the local curvature of space-time, commonly identified with the vacuum. Any chemical or phase transformation is caused by an interaction that changes the symmetry of the gauge field. It is convenient to describe such events in terms of a Lagrangian density which is invariant under gauge transformation and reveals the details of the interaction as a function of the symmetry. The chemically important examples of crystal nucleation and the generation of entropy by time flow will be discussed next. The important conclusion is that in all cases, the gauge field arises from a symmetry of space-time and the nature of chemical matter and interaction reduces to a function of space-time structure. [Pg.166]

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