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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 ...
The theory of diffusion-controlled reaction was originally utilized by R.A. Alberty, Gordon Hammes, and Manfred Eigen to estimate the upper limit of enzyme-substrate reaction. [3] [4] According to their estimation, [3] [4] the upper limit of enzyme-substrate reaction was 10 9 M −1 s −1.
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.
Reaction–diffusion systems are mathematical models that correspond to several physical phenomena. The most common is the change in space and time of the concentration of one or more chemical substances: local chemical reactions in which the substances are transformed into each other, and diffusion which causes the substances to spread out ...
The reaction order is 1 with respect to B and −1 with respect to A. Reactant A inhibits the reaction at all concentrations. The following reactions follow a Langmuir–Hinshelwood mechanism: [4] 2 CO + O 2 → 2 CO 2 on a platinum catalyst. CO + 2H 2 → CH 3 OH on a ZnO catalyst. C 2 H 4 + H 2 → C 2 H 6 on a copper catalyst. N 2 O + H 2 ...
This is referred to as air inhibition and is a diffusion-controlled reaction with rates typically in the order of 10 7 –10 9 mol −1 s −1, [3] the resulting peroxy radicals (ROO•) are less reactive towards polymerisation. However air stabilisation is not suitable for monomers with which it can form explosive peroxides, such as vinyl ...
The cage effect can be quantitatively described as the cage recombination efficiency F c where: = / (+) [9] Here F c is defined as the ratio of the rate constant for cage recombination (k c) to the sum of the rate constants for all cage processes. [9]
It is formed in vivo from the diffusion-controlled reaction of nitrogen monoxide (ON •) and superoxide (O •− 2). It is an isomer of nitric acid and isomerises with a rate constant of k = 1.2 s −1, a process whereby up to 5% of hydroxyl and nitrogen dioxide radicals may be formed. It oxidises and nitrates aromatic compounds in low yield.