Chemical Forums
Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: noor123 on January 15, 2015, 07:32:45 AM
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How does the collision theory explain the rate laws for complex or consecutive reactions?
I know that the collision theory is about how for instance the increase in conc. of reactants lead to more successful collisions and thus making the rxn faster, or also change in temperature or pressure can have its effect. And since complex reactions can have several intermediates, can increasing the concentration of reactants of the first reaction lead to making the intermediates more faster and thus the products aswell?
Am i thinking on the right way?
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I'm not sure I understand what the question is.
Chemical kinetics remains a very empirical or semi-empirical discipline. First principles approaches like collision theory are successful to some degree, but applying them to even simple reactions can be anything but straightforward. Complex reactions are... well, complex.
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Another approach would be to treat only the elementary reactions in a detailed way. then describe the whole mechanism in a phenomenological one.
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Another approach would be to treat only the elementary reactions in a detailed way. then describe the whole mechanism in a phenomenological one.
It must be kept in mind that there are possibilities to develop a detailed mechanism but its exact verification may be impossible to do. The applied combustion hydrocarbons mechanisms have been verified based on the macro values eg. flame speed. No one says that GRI mech 3.0 is 100% correct.
Additional problem of nowadays is real process simulation with consideration a detailed chemical mechanism and a physical phenomena (convection, diffusion, thermodiffusion, dynamic of fluid). There aren't such strong CPUs in the world to carry on this simulation (or maybe are :) ).
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but its exact verification may be impossible to do
you can argue that that's always impossible. but that's not the question here, as I understand it.