Read the sections on Collision Theory, Transition State Theory, and Molecular Dynamics in...

Read the sections on Collision Theory, Transition State Theory, and Molecular Dynamics in the Professional Reference Shelf on the CD-ROM.

(a) Use collision theory to outline the derivation of the Polanyi-Semenov equation, which can be used to estimate activation energies from the heats of reaction, AHR, according to the equation

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(b) Why is this a reasonable correlation? (Hint: See Professional Reference Shelf 3R. 1: Collision Theory.)

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(c) Consider the following family of reactions:

Estimate the activation for the reaction

which has an exothermic heat of reaction of 6 kcal/mol (i.e., ΔHR = −6 kcal/mol).

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(d) What parameters vary over the widest range in calculating the reaction rate constant using transition state theory (i.e., which ones do you need to focus your attention on to get a good approximation of the specific reaction rate)? (See Professional Reference Shelf R3.2.)

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(e) List the assumptions made in the molecular dynamics simulation R3.3 used to calculate the activation energy for the hydrogen exchange reaction.

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(f) The volume of the box used to calculate the translational partition function for the activated complex was taken as 1 dm3. True or False?

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(g) Suppose the distance between two atoms of a linear molecule in the transition state was set at half the true value. Would the rate constant increase or decrease over that of the true value and by how much (i.e., what factor)?

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(h) List the parameters you can obtain from Cerius2 to calculate the molecular partition functions.