1. http://www.absorblearning.com/media/item.a ction?quick=w8 Thornburg 2014

2. Understanding Reversible Reactions & Equilibrium Thornburg 2014

3. Reversible Reactions A reversible reaction is a reaction in which the reactants are changing into products and products are changing back into reactants at the same time Example: 2SO 2 + O 2 2SO 3 Thornburg 2014

4. Equilibrium When the rate of the forward reaction is the same as the rate of the reverse reaction, this is called equilibrium At chemical equilibrium, there is no net change in the amount of reactants and products Thornburg 2014

5. Room ARoom B Reactants Products + Heat Thornburg 2014

6. A parallel Example… When the number of students leaving the room and entering the room is the same during a 5 minute passing period The total number of students does not change, but it is a new group of students in the room

7. Le Chatelier’s Principle If a stress is applied to a chemical system, the system will change in a way that relieves the stress and restores equilibrium You need to know how the following 3 stresses will affect the equilibrium of a system: temperature pressure Concentration Thornburg 2014

8. Room A (Heater is on) Room B (Nice and Cool – Air conditioner is on) Reactants Products + Heat If we increase the temperature, which reaction will speed up – the forward reaction or the reverse reaction? Thornburg 2014

9. If the temperature is increased, equilibrium will shift and the reaction which absorbs heat will speed up. Thornburg 2014

10. Room ARoom B Reactants Products + Heat If we increase the concentration of reactants, which reaction will temporarily speed up – the forward reaction or the reverse reaction? Thornburg 2014

11. Reactants Products If the concentration of reactants is increased, the forward reaction will temporarily increase If the concentration of products is increased, the reverse reaction will temporarily increase Thornburg 2014

12. Room A Room B Reactants Products 3 + Heat 1 If we increase the pressure, which reaction will speed up – the forward reaction or the reverse reaction? Thornburg 2014

13. If pressure is increased, equilibrium will shift and the reaction which creates fewer particles will be speed up Thornburg 2014