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Diffusion-controlled (or diffusion-limited) reactions are reactions in which the reaction rate is equal to the rate of transport of the reactants through the reaction medium (usually a solution). [1] The process of chemical reaction can be considered as involving the diffusion of reactants until they encounter each other in the right ...
In recent times, reaction–diffusion systems have attracted much interest as a prototype model for pattern formation. [20] The above-mentioned patterns (fronts, spirals, targets, hexagons, stripes and dissipative solitons) can be found in various types of reaction–diffusion systems in spite of large discrepancies e.g. in the local reaction ...
Fiveling (decahedral nanoparticle) showing diffusion growth at tips. [52] For completeness, there is a different type of kinetic control of shapes called diffusion control, [53] [54] which can lead to more complex shapes such as dendrites [55] and others, [39] for instance the star-shaped decahedral nanoparticle shown in the figure.
The encapsulated molecules or radicals are called cage pairs or geminate pairs. [5] [6] In order to interact with other molecules, the caged particle must diffuse from its solvent cage. The typical lifetime of a solvent cage is 10-11 seconds. [7] Many manifestations of the cage effect exist. [8]
Transition state theory explains the dynamics of reactions. The theory is based on the idea that there is an equilibrium between the activated complex and reactant molecules. The theory incorporates concepts from collision theory, which states that for a reaction to occur, reacting molecules must collide with a minimum energy and correct ...
The total reaction may be diffusion controlled (the electron transfer step is faster than diffusion, every encounter leads to reaction) or activation controlled (the "equilibrium of association" is reached, the electron transfer step is slow, the separation of the successor complex is fast). The ligand shells around A and D are retained.
A necessary condition for thermodynamic control is reversibility or a mechanism permitting the equilibration between products. Reactions are considered to take place under thermodynamic reaction control when the reverse reaction is sufficiently rapid that the equilibrium establishes itself within the allotted reaction time. In this way, the ...
Hantz reactions are a class of pattern-forming precipitation reactions in gels implementing a reaction–diffusion system. The precipitation patterns are forming as a reaction of two electrolytes : a highly concentrated "outer" one diffuses into a hydrogel , while the "inner" one is dissolved in the gel itself.