Lesson_28 - Collision theory of gaseous reactants For the bimolecular elementary reaction A B products to occur it is necessary that molecules of A

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Lesson 28 Collision theory of gaseous reactants For the bimolecular elementary reaction, A + B products to occur, it is necessary that molecules of A and B collide. Will all colliding molecules react? The rate of molecular collisions per volume can be estimated by the expression: V N V N u s cm collision . No B A 2 3 πσ =
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Lesson 28 Calculating the frequency of collisions in a gas reaction s cm 10 5 cm 10 3 cm 10 2.8 4 8 3 19 × = × = × = = - u V N V N B A σ s cm collisions 10 1.1 s cm collision No. 3 29 3 × = Molecular density: Molecular radius: Average speed: A very high frequency!
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Lesson 28 Activation energy If molecular collisions were the only controlling factor for chemical reactions in the gas phase, this very high rate of molecular collisions would indicate that all gas reactions would be extremely fast. This does not agree with experimental data on gas reactions. In fact, reactant molecules must achieve a given energy level ( activation energy ) before the reaction can take place.
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Lesson 28 Reaction profile
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Lesson 28 An analogy for transition state and activation energy of chemical reactions
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Lesson 28 Temperature effects
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This note was uploaded on 04/13/2009 for the course CHEMISTRY 102 taught by Professor Soares during the Spring '09 term at Waterloo.

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Lesson_28 - Collision theory of gaseous reactants For the bimolecular elementary reaction A B products to occur it is necessary that molecules of A

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