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| Recap |
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this Lecture you have learnt the following |
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Summary |
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The mechanisms of chemical reactions have always kept chemists busy as these studies have lead to the discovery of a wide variety of elementary reactions (i.e., reactions in which molecularity is the same as the order with no further possibility of a break up into additional constituent reactions) and the detection of several short lived intermediates. The mechanism of a reaction need not be unique as there could be several pathways leading to the products. In addition, the mechanisms often change when temperature and pressure conditions are changed and when catalysts are added to enhance the reaction rates. Once the steps or the elementary reactions constituting the reaction mechanism are identified we need an equation for the rate law. Convenient approximations (which are valid over significant periods during the reactions) such as the steady state approximation (wherein the small concentration of an intermediate remains constant) and preequilibrium ( wherein the reactants quickly come to a near equilibrium with an intermediate) are useful in simplifying the rate equations. Using these, it is possible to identify suitable rate coefficients for reaction process. |
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Examples of reaction mechanisms of decomposition of ozone, oxidation of nitric oxide, unimolecular reactions and enzymes kinetics have been given in this lecture. With the knowledge gained in this lecture, you will be able to derive the rate law if the reaction mechanism is given to you. Similarly, given the strichiometry and the order of a reaction you may also be able to propose a mechanism for a given reaction. There is a good chance that your mechanism may be correct! |
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Congratulations, you have finished Lecture 28. To view the next lecture select it from the left hand side menu of the page |
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