Rates Solution Page 2

  1. (a) Define collision theory as an important part of reaction kinetics.

Refer to class notes

(b) In the reaction CO + ½ O2 → CO2 (all reactants and products are gases)

A particular CO molecule collides with an oxygen molecule once in 10-9 secs. Yet virtually no reaction occurs at room temperature. Explain how collision theory is extended to explain this observation.

When reactants collide they should (i) possess the energy of activation and (II) proper orientation. For this to happen, the reactants should collide with sufficient kinetic energy. Once the activated complex is formed they will easily change into products.

  1. A small increase in temperature of 10oC may double or triple the rate of the reaction. Explain this result by using the concept of activation energy and the Boltzmann Distribution Curve (kinetic energy distribution curve) Refer to Maxwell Boltzmann distribution curve.

When there is a ten degree rise in temperature, if the area under the curve, which reflects the molecules possessing energy of activation or greater doubles or triples the rate of reaction doubles or triples as the case may be. Draw the graph and explain.

  1. Given the reaction NO + ½O2 → NO2 (All are gases). What is the effect on the rate of production of nitrogen dioxide (increase or decrease) if the following happens?

(1) More nitrogen oxide (nitric oxide) is added: Increased Rate

(2) More oxygen is added: Increased Rate

(3) The temperature of the reaction is lowered: Decreased Rate

(4) a catalyst is added: Increased Rate

  1. (a) List the three characteristics of the activated complex

(1) A Short Life

(2) High Potential energy

(3) Has a transition structure

(b) Assuming that the reaction in question #5 occurs in one step, propose a structure for the activated complex

BC = Bond Changing or Bond Weakening

BM = Bond Making or new attractive forces forming

BB = Bond Breaking

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