Characteristic time of reaction

Residence time solid to characteristic time of reaction... 

Figure 17 shows the time evolution of the potential energy of RDX for temperatures from T = 1200 to 3000 K for the three densities studied. We find that higher densities lead to faster chemistry, and the temporal evolution of the potential energy can be described rather well with a simple exponential function, from which we extract an overall characteristic time of reaction (the solid lines in Fig. 17 shows the exponential functions). 

The characteristic time of reaction 1 with respect to NO removal is ii = (k [O3])... 

At conditions in the upper stratosphere, the characteristic time of reaction 4.30 for reaction of Cl is about 1 second and that of reaction 4.31 for reaction of CIO is approximately 1... 

It has also been demonstrated that the extent of the enhancement increases with the ratio 5 of the characteristic time of reaction to the characteristic time of permeation, as long as the flow rate of the permeate, which increases with the membrane area, remains below the feed flow rate. 

Water was produced through the reduction of stored NOx and was detected at the reactor exit with a time delay of about 50 s, that compared well with the characteristic time of C02desorption. Likewise, the consumption of C02 was ascribed to the reverse of reaction (10), which implied readsorption of C02 on BaO/Ba(OH)2 once NO had been reduced. 

The development of a quantitative theory of a free-radical copolymerization implies the derivation of equations for the rate of the monomers depletion and the statistical characteristics of the chemical structure of macromolecules present in the reaction system at the given conversion p of monomers. Elaborating such a theory one should take into account a highly important peculiarity inherent to any free-radical copolymerization. This peculiarity is that the characteristic time of a macroradical life is appreciably less than the time of the process duration. Consequently, its products represent definitely... 

As discussed in an earlier section, <5L is the characteristic length of the flame and includes the thermal preheat region and that associated with the zone of rapid chemical reaction. This reaction zone is the rapid heat release flame segment at the high-temperature end of the flame. The earlier discussion of flame structure from detailed chemical kinetic mechanisms revealed that the heat release zone need not be narrow compared to the preheat zone. Nevertheless, the magnitude of <5L does not change, no matter what the analysis of the flame structure is. It is then possible to specify the characteristic time of the chemical reaction in this context to be... 

The batch-batch reactor becomes a practical device when the characteristic times for reaction and deactivation are of the same order of magnitude. If they are not and if deactivation is much slower, then C oo becomes very low and difficult to measure accurately. Fortunately, this ratio can be controlled by the experimenter by proper choice of W V. 

Two-photon excitation at X = 307 nm provides 186 kcal/mol of energy to tetra-hydrofuran (THF) the excited molecule breaks a C—O bond with a characteristic time of 55 15 fs to form an oxytetramethylene diradical. This species, now with 114 kcal/mol of available energy, has a lifetime of 65 15 fs it decays primarily through a C—C p-cleavage reaction, giving the trimethylene diradical (42 amu, t 120 fs). The cleavage to trimethylene is the dominant reaction. ... 

For reactions between ions of like charge, the term in xrc (1 + kR) 1 should be multiplied by a number 0.6—0.9, whereas for unlike charges, this number is 0.3—0.6 depending on R. Certainly, eqn. (58) is not the appropriate correction term. In eqn. (57), the ionic relaxation time for univalent ions is Tjon = 1/(477[rc Dn), where n is the electrolyte concentration. This is also the characteristic time for reaction (pseudo first-order decay time) of a univalent species reacting with one or other ion of the... 

Research on the temperature dependence of charge recombination reaction (1) has shown the P700 decay time to depend on temperature at 150 K < T < 270 K. Below 150 K only 10-30% of the total number of P1 particles accumulated under the action of light disappear after the light is switched off, the characteristic time of their decay being independent of temperature. 

From the results of the investigations discussed in this and in previous chapters it follows that tunneling recombination reactions proceed relatively slowly. Thus, at the typical values of the parameters ve = 10ir s 1 and ae = lA in the expression for the probability of electron tunneling, the characteristic tunneling times to distances of R = 10-20 A amount to 10 6-102s. These times are far longer than the characteristic time of diffusional approach of particles separated by the same distances in water solutions ... 

The criterion of homochronity tk/(P, where d is the characteristic dimension of the system, k is the thermal diffusivity and r is the characteristic time of the chemical reaction. Due to the strong dependence of the chemical reaction rate on temperature (see the next two criteria), it is necessary to define the temperature to which the quantity r relates. We will relate it to the theoretical temperature of combustion. 

One way or another we have a characteristic time of the chemical reaction which, together with the detonation velocity, yields a characteristic length Dt of occurrence of the chemical reaction. Direct comparison of this length with the tube diameter does not make sense since all motions occur along the tube axis. Therefore we may expect that the characteristic distance of braking and cooling will enter—the quantity d/ where is the dimensionless braking coefficient.10... 

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