1. Collision Theory

2. Use the Collision Theory to explain the rate of chemical reactions. Include: Activation energy Draw potential energy diagrams for various reactions. Include: exothermic, endothermic, activated complex, enthalpy Additional KEY Terms transition state

3. In order for a chemical reaction to occur, the reacting particles must collide with each other. If the particles do not collide, no reaction occurs. The collision theory states:

4. 1. Particles must collide with correct orientation

5. 2. Particles must collide with enough energy: Activation Energy (E A ): Minimum energy needed for a reaction to take place. Energy is required to break old bonds Energy (Potential) is stored within new bonds Colliding particles have Kinetic Energy (velocity) If total energy (PE + KE) ≠ Activation Energy - NO REACTION

6. Activation Energy Particles with Activation Energy Each reaction has its own specific activation energy. Maxwell-Boltzman Curve Frequency of successful collisions determines the Rate of a reaction.

7. At point of collision: Particles form unstable intermediate particle called the activated complex or transition state. AC has maximum potential energy but exists for a very small time. + Kinetic Energy Potential Energy Kinetic Energy

8. Enthalpy (H) is the heat content or total energy possessed by the particles in a system. Energy released or absorbed in a reaction is called the change in enthalpy, ΔH, or heat of reaction. Units of energy are Joules (J). ΔH = H products - H reactants

9. -ΔH : products have less enthalpy (energy) then reactants. Heat flows out of the system – exothermic. +ΔH : products have more energy than reactants. Heat absorbed into the system – endothermic. ΔH = 10 - 15ΔH = H products - H reactants ΔH = 15 - 10ΔH = H products - H reactants

10. Reaction coordinate diagram or Potential energy (PE) diagram Represents the PE change during a reaction.

11. Greater activation energy - slower reaction rate - longer the reaction takes.

13. 2 H 2 + O 2 → 2 H 2 O

14. CH 3 CH 2 Br + OH − → CH 3 CH 2 OH + Br −

15. CAN YOU / HAVE YOU? Use the Collision Theory to explain the rate of chemical reactions. Include: Activation energy Draw potential energy diagrams for various reactions. Include: exothermic, endothermic, activated complex, enthalpy Additional KEY Terms transition state