Kinetics+Part+4 - the reverse reaction. For an endothermic...

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Effects of Concentration and Temperature Collision Theory – The Basis of the Rate Law Concentrations are multiplied in the rate law due to probability of collisions. Temperature affects frequency of collisions. Increasing the temperature increases the average speed of the particles and increases their frequency of collision. In the vast majority of collisions the molecules rebound without reacting. There must be an energy threshold that must be reached – Activation Energy. Only those collisions with enough energy to exceed E a can lead to reaction. The magnitudes of both E a and T affect the fraction of sufficiently energetic collisions. A reversible reaction has two activation energies, one in the forward direction and one in the reverse. Higher T increases reaction rate in both directions For an exothermic process the forward reaction is faster than
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Unformatted text preview: the reverse reaction. For an endothermic process the reverse reaction is faster than the forward reaction. These conclusions are consistent with the Arrhenius equation the larger the E a , the smaller the value of k , and the slower the reaction: Larger E a smaller k decreased rate 1 Molecular Structure and Rate The molecules must collide such that the reacting atoms make contact. A collision must have enough energy and a particular molecular orientation to be effective. Transition State Theory The Activated State CH 3 Br + OH CH 3 OH + Br Draw an energy diagram for this reaction depicting the transition state (activated complex). Transition state theory suggest that every reaction (and every step in an overall reaction) goes through its own transition state. 2...
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Kinetics+Part+4 - the reverse reaction. For an endothermic...

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