Collision Theory
Chemistry: AQA A Level, topic 1.5.1
Collision Theory
Collision theory is the theory of how reactions happen.
When will a reaction happen?
- For a reaction between two molecules to happen, they must come into close proximity with each other.
- For a particular reaction to happen, several conditions must be met:
- The correct part of the molecules must collide.
- The molecules must collide with enough energy to react.
Steric factor
- The steric factor is the fancy name for saying that the location of a collision matters.
- For example, if you were trying to react the OH bond in ethanol (CH3CH2OH), a collision with the CH3 group wouldn't do anything.
Activation energy
- The activation energy is the energy needed for a reaction to happen.
- The activation energy is used to break the bonds in the reactants before new bonds can form in the products.
- For both reasons of activation energy and steric factor, most collisions do not result in a reaction.
Test yourself on Collision Theory
What information is contained within enthalpy profile diagrams?