1.  Le Châtelier’s Principle

2. The Principle  When a chemical system at equilibrium is disturbed by a change in a property, the system adjusts in a way that opposes the change!  [CoCl 4 ] 2- (aq) + 6H 2 0 ⇌ [Co(H 2 O) 6 ] 2+ + 4Cl - + Heat  Left side: blue, right side: pink

3. Summary VariableType of changeResponse of system ConcentrationIncreaseShifts to consume the added reactant or product DecreaseShifts to replace removed reactant or product TemperatureIncreaseShifts to use some of the added thermal energy DecreaseShifts to replace some of the removed thermal energy VolumeIncrease (decrease pressure)Shifts towards the side with larger total amount of gases Decrease (increase pressure)Shifts towards the side with the smaller amount of gases

4.  Reaction Game! In your groups, decide whether the equilibrium shifts left or right!

5. Concentration CCl 4 + 2 HF ⇌ CCl 2 F 2 + 2HCl 1. Remove some HF 2. Add some drops of HCl 3. Add CCl 4 4. Remove CCl 2 F 2

6. Temperature AND Concentration CH 4 + 2O 2 ⇌ 2H 2 O + CO 2 1. Removing heat 2. Syphoning out CO 2 3. Doing the reaction in an area with little oxygen 4. Doing the reaction in a sauna

7.  PRACTICE p. 457 #1,4-8(a,b)