Decomposition, factors affecting

Reacting species, predominant, 80 Reaction coordinate, 133 Reaction heat, 135 additivity of, 111 measurement of, 111 Reaction rates, 124 factors affecting, 125 Reactions, 38,129 acid-base, 188 balancing, 42, 217, 219 calcium carbonate decomposition, 143... 

DS Tarbell, EJ Longosz. Thermal decomposition of mixed carboxylic-carbonic anhydrides. Factors affecting ester formation. J Org Chem 24, 774, 1959. 

Rates of Gas-Phase Reactions. Reaction rates have been reported for only a few CVD gas-phase reactions, and most reports are primarily for the silane system. Because of the high temperatures and low pressures used in CVD, the direct use of reported gas-phase rate constants must be done with care. In addition to mass-transfer and wall effects, process pressure may be another factor affecting reaction rates. Process pressure affects major CVD processes, such as the deposition of Si from SiH4 and GaAs from Ga(CH3)3, reactions that involve unimolecular decomposition. The collisional activation, deactivation, and decomposition underlying these reactions can be summarized qualitatively by the following reactions (139, 140) ... 

Table 3.4 Factors Affecting the Decomposition of Animal Bodies...

Nevertheless, the kinetics of decomposition are of sufficient interest, for both theoretical and practical reasons, that it seems worthwhile to include the results of at least the more carefully done studies. In this section we summarize features common to all decompositions and the factors affecting decomposition rates. The discussion is essentially limited to solids, since most experimental and theoretical work has been done in this area. It should be pointed out that many of the theoretical foundations were laid several decades ago, and that newer developments deal mostly with refinements. Kinetics of the individual compounds are treated in their respective sections. 

Valiela, I., Teal., J.M., Allan, S.D., van Etten, R., Goehungel, D., and Volkman, S. (1985) Decomposition in salt marsh ecosystems the phases and major factors affecting disappearance of above-ground organic matter. J. Exp. Mar. Biol. Ecol. 89, 29-54. 

Another point is that the reduction and oxidation potential limits (electrochemical window) are defined as the potentials at which the current density reaches a predefined value that is arbitrarily chosen [40, 48], Ue et al. also mention that the same problem arises in the choice of the sweep rate [40]. For example Egashira and coworkers obtained a log I- U line shifted to a higher position at a faster potential scan in comparison to a slower scan because of non-Faradaic currents such as the larger charging currents of the double-layer, and the decomposition of impurities [41]. The last factor affecting the electrochemical window is the electrode itself, its composition and its morphological surface structure, which defines the electrocatalytic properties [40]. 

Even with PI, theoretically one of the simplest ionization processes, the internal energy distribution, P(E), of the molecular ion cannot be predicted on the basis of Franck—Condon factors alone. Autoionization is well-known as being important [15, 177, 637, 640, 800], as is the more recently recognised effect of shape resonance [220, 803, 906]. It has also been shown that the onset of a decomposition can affect the energy distribution, P(E), [801, 802]. The latter effect is possibly a consequence of competition between neutral and ionic decompositions. 

The rates of decomposition determined in FIK [43] depend upon the internal energy distribution of the assembly of reactant ions. The energy distribution produced through FI is not a well-characterised property and factors affecting the internal energy warrant discussion (see Sect. 6.1). The literature on FIK of different classes of molecules is surveyed in Sects. 6.2—6.5. 

Rapid and complete solvent evaporation is required for optimum performance. Atomisation occurs in the flame reaction zone, i.e. the conversion of sample molecules into atoms. Three factors affect the number of atoms formed. Firstly, the anion with which the metal atom is combined. Calcium chloride for instance is more easily dissociated than calcium phosphate. The second factor is flame temperature. Higher temperatures cause more rapid decomposition and, indeed, are often specifically required for elements which form refractory oxides. Finally, gas composition may affect the rate of atomisation if the constituents in the gas react with the sample or its derivatives. In the outer zone of the flame the atoms are burned to oxides. In this form they no longer absorb radiation at the wavelength of the uncombined ground state atoms. 

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