Chem Collision Theory Flashcards

Collision Theory

Theoretical model that states that molecules must collide in order to react

one particle and container wall

two particles (three particle collisions are very rare)

Effectiveness of collisions is determined by

_______ & ___________

Reactant Orientation & Energy

Reaction Rate

the speed at which reactant particles achieve the activation energy

Activation energy (E_a)

energy needed to start a reaction and form the activated complex

Activated complex

short-lived transition state between reactants and products at the point where energy is the greatest in a reaction

Factors Affecting Reaction Rates

1. Nature of Reacting Species

• Complexity

• State

  • Gases react more easily than solids or liquids

  • Aqueous solutions react almost instantaneously\

    2. Temperature

• Almost always increases reaction rate

Higher temp →
greater kinetic energy →
More frequent collisions

3. Concentrations of Reactants

• More reactants → more collisions

4. Surface Area: Increases frequency of collisions

5. Pressure (Gases): Increase pressure → increase reaction rate

6. Addition of a catalyst

• Does not change the reaction

• Lowers activation energy