Lecture 11: Collision Theory

Collision Theory

States that there are three things that must happen in order for a reaction to take place

1. Molecules must collide

2. Molecules must be in the proper orientation

3. Enough kinetic energy in order for the reaction to occur

The Maxwell-Boltzman Distribution

At a given temperature some molecules have more energy than others

Activation energy

• Energy needed to initiate reaction and overcome reaction barrier

• Difference between reactants and activated complex

The Arrhenius equation

k = Ze^-E_a/RT

The frequency factor

Describes the number of times two molecules collide

• Varies only slightly across small temperature ranges

• Accounts for both orientation effects and collision frequency

What is the A factor equal to?

The high temperature limiting rate constant for the reaction

Spontaneous processes

physical or chemical change that occurs with no outside intervention, however some energy may be supplied to get process started

Catalyst

Substance that increases rate of reaction by lowering the activation energy by changing the mechanism of the reaction (alternate path).