Chemical reactions, effects

Chemical reaction effects can be treated as first order... 

Cambridge) and G. Porter (London) studies of extremely fast chemical reactions, effected by disturbing the equilibrium by means of very short pulses of energy. 

Table 12.1 Consecutive Chemical Reactions Effect of Final Time on the Selection of the Best Grid Point Using the Volume Criterion ...

Particle attrition not due to thermal or chemical reaction effects (i.e., mechanical attrition) occurs much more rapidly in the grid region of fluidized beds than in the bulk of the bed. This is due to high-velocity gas... 

There are chemical reactions between the released contaminant and ambient air or surfaces. If the released contaminant reacts, any reacted material can no longer be considered airborne (although the reaction products may also be hazardous), and so chemical reactions effectively reduce the rate or amount of airborne contaminant. Some reactions can be characterized as dry or wet deposition. 

In the biomedical literature (e.g. solute = enzyme, drug, etc.), values of kf and kr are often estimated from kinetic experiments that do not distinguish between diffusive transport in the external medium and chemical reaction effects. In that case, reaction kinetics are generally assumed to be rate-limiting with respect to mass transport. This assumption is typically confirmed by comparing the adsorption transient to maximum rates of diffusive flux to the cell surface. Values of kf and kr are then determined from the start of short-term experiments with either no (determination of kf) or a finite concentration (determination of kT) of initial surface bound solute [189]. If the rate constant for the reaction at the cell surface is near or equal to (cf. equation (16)), then... 

Dynamic Behaviour Reactor behaviour during start-up is illustrated in Figure 4. The reactor was operating initially at normal conditions but without o-xylene in the feed, when the o-xylene flow rate was raised to 152 g/hr. The hot spot developed quickly (within 3 minutes) at the reactor exit and propagated upstream as heat transfer and chemical reaction effects led to the heating of the catalyst pellets to their steady-state temperatures. 

Let the symbol H be read as the effective concentration or activity of H and the symbol [H ] be read as the concentration of H. The effective concentration H refers to the ions of H that actually participate in a reaction. This is different from the concentration [H ], which refers to the actual concentration of iG, but not all the actual concentration of this H participate in the chemical reaction. Effective concentration is also called activity. The effective concentration or activity of a solute is obtained from its actual concentration by multiplying the actual concentration by an activity coefficient,/(i.e., H =/[H ]). 

General model for physical transport of solute disregarding any chemical reaction effects. The model accounted for the continuous phase resistance and the interfacial resistance and permeation through a composite emulsion globule. It also quantified the loss in extraction efficiencies by leakage due to membrane breakage. 

IIIK) Farage, V. J., Janjic, D. Uncatalyzed Oscillatory Chemical Reactions, Effect of Different 1982-3 Constraints during the Oxidation Reaction of 1,4-Cyclohexanedione by Acidic Bromate. Chem. Phys. Lett. 93(6) 621-624. 

Benderskii, V., Goldanskii, V. and Makarov, D. (1991). Low-temperature chemical reactions. Effect of symmetrically coupled vibrations in collinear exchange reactions. Chem. Phys. 154, 407-424... 

The optimal results indicate both the thermal separation and chemical reaction effects. The more product alcohol in the entire column, the less reflux ratio we need to satisfy the purity restrictions. The slow increase of the reflux ratio during the first three hours is allowed, since a large amount of product alcohol results from the drastic increase of the feed flow of the educt alcohol. However, when the feed flow has reached its maximum value, the reflux ratio needs to increase drastically in order to ensure the distillate purity constraint. The decrease of the reflux ratio can be explained with the time delay between the feed supply of educt alcohol and the resulting effect of formation of product alcohol caused by the chemical reaction. 

A pure batch reactor, used for a rapid exothermic reaction, is inherently very unstable. A well known example of such a reactor is a bomb. When we want to control a chemical reaction effectively, also in the laboratory, the semi-batch mode is usually preferred. A certain amount of one reactant (A) is put into the reactor, and heat to a temperature that makes the reaction possible. The other reactant (B) is introduced into the reactor with a controlled rate. When the reactor has adequate cooling, the reactor temperature can be kept effectively within desired limits. The practical problem is a how to adjust the cooling rate to the strongly varying reaction rate. 

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