Sunday, January 22, 2012

Rates of Reaction #3: Rate Theories

Collision theory:
  • Reaction rate is directly proportional to the number of successful collisions per second
  • Factors that effect the success of a collision:
    • Orientation: Molecules have to collide at certain angles in order for them to react
    • Kinetic Energy: When molecules collide, they must have enough kinetic energy in order for them to undergo reaction

Transition State Theory
Transition state complexes occur at the peaks of the potential energy graphs, and they are large molecules made up of all the reactants. Bonds are forming and breaking at the same time. 

Catalysts can reduce the activation energy by one or more of the following mechanisms:
  • bend or stretch bonds to make them easier to break
  • bring two reactants closer together
  • provide a different reaction
  • provide a microenvironment