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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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In this lecture, you have been introduced to some of the common techniques employed in experimental chemical kinetics. In all these methods, the concentration of some or all of the species involved in a chemical reaction need to be measured as a function of time. If reactants/products are optically active, a physical property such as optical rotation can be used to measure changes in concentration. If the conductance of the reaction mixture changes significantly (because of the conductance of the reactants/products being significantly large), then it is a good measure for assessing time dependent concentrations. A time tested classical chemical method to study the extent of a reaction is to take out a small portion of the reaction mixture (such as half or one milliliter), freeze or quench the progress of the reaction and estimate the concentration of one of the species. Modern kinetics is progressing towards studying faster and even faster chemical events. |
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Flash photolysis combined with absorption spectroscopy can study reactions on a microsecond time scale. Laser induced fluorescence extends the measurements to nanosecond time scales. It has been possible to extend the time resolution to pico seconds and femtoseconds using very short laser pulses (pump) to initiate a reaction and then use a second laser pulse (probe) to monitor the extent or the progress of the reaction. These techniques have been briefly described towards the end of the lecture. All these methods involve a very high degree of experimental sophistication involving precision optics, electronics and spectroscopy |
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Congratulations, you have finished Lecture 27. To view the next lecture select it from the left hand side menu of the page |
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