“equilibrium”  what does it mean?  what word does it look like?  what does it mean? ...

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  • Slide 1
  • Equilibrium What does it mean? What word does it look like? What does it mean? What word does it look like?
  • Slide 2
  • Aim: How can we look at systems at equilibrium? Equilibrium: a state of balance Dynamic Equilibrium: when overall rates of forward and reverse reactions are equal This is a Reversible Equilibrium and is indicated by a double arrow Equilibrium: a state of balance Dynamic Equilibrium: when overall rates of forward and reverse reactions are equal This is a Reversible Equilibrium and is indicated by a double arrow
  • Slide 3
  • Physical Equilibrium Physical Equilibrium is balance in physical processes Phase equilibrium: equilibrium between phases Physical Equilibrium is balance in physical processes Phase equilibrium: equilibrium between phases
  • Slide 4
  • Solution Equilibrium Solution Equilibrium: dissolving & crystallization happening at equal rate liquid-gas liquid-solid
  • Slide 5
  • Chemical Equilibrium CH 4 (g) + H 2 O (g) 3 H 2 (g) + CO (g)
  • Slide 6
  • Chemical Equilibrium CH 4 (g) + H 2 O (g) 3 H 2 (g) + CO (g)
  • Slide 7
  • Homework Finish equilibrium review pages
  • Slide 8
  • Remember: Equilibrium is Stability CH 4 + H 2 O 3 H 2 + CO Fwd rxn rate = Rev Rxn rate Using up reactants to make products CH 4 + H 2 O 3 H 2 + CO Fwd rxn rate = Rev Rxn rate Using up reactants to make products
  • Slide 9
  • How will a closed system react when a stress if applied? equilibrium stress new equilibrium
  • Slide 10
  • Le Chateliers Principle Closed systems will adjust to balance stresses Concentration, temperature, pressure Shifts are increased reaction rates in either Fwd (right) or Rev (left) directions Closed systems will adjust to balance stresses Concentration, temperature, pressure Shifts are increased reaction rates in either Fwd (right) or Rev (left) directions
  • Slide 11
  • Slide 12
  • Slide 13
  • Concentration Pen/pencil trick, pointing towards shift A + B C Add-Away, Take-Towards Pen/pencil trick, pointing towards shift A + B C Add-Away, Take-Towards
  • Slide 14
  • Slide 15
  • Slide 16
  • https://www.youtube.com/watch?v=7zu UV455zFs
  • Slide 17
  • Concentration Add-Away
  • Slide 18
  • Concentration Take-Towards
  • Slide 19
  • Le Chateliers Principle: Temperature Treat heat/energy like any other reactant Adding heat favors reaction Removing heat favors reaction Treat heat/energy like any other reactant Adding heat favors reaction Removing heat favors reaction
  • Slide 20
  • N 2 + 3 H 2 2 NH 3 + 22 kJ
  • Slide 21
  • 12.6 kJ + H 2 + I 2 2 HI
  • Slide 22
  • Do Now: Answer the following questions 1. What is Le Chateliers Principle? 2. Label the forward and reverse reactions as endothermic or exothermic: CO (g) + 3 H 2 CH 4 (g) + H 2 O (g) + heat 3. In which direction will equilibrium shift if the temperature is increased? 4. In which direction will equilibrium shift if the temperature is decreased? 1. What is Le Chateliers Principle? 2. Label the forward and reverse reactions as endothermic or exothermic: CO (g) + 3 H 2 CH 4 (g) + H 2 O (g) + heat 3. In which direction will equilibrium shift if the temperature is increased? 4. In which direction will equilibrium shift if the temperature is decreased?
  • Slide 23
  • Pressure Only for gases; count # of molecules on each side If # is equal, pressure has no effect pressure shifts towards fewer molecules pressure shifts towards more molecules Only for gases; count # of molecules on each side If # is equal, pressure has no effect pressure shifts towards fewer molecules pressure shifts towards more molecules
  • Slide 24
  • Pressure Example 4 NH (g) + 5 O 2 (g) 4 NO (g) + 6 H 2 O (g) = gas molecules = gas molecules Increase pressure: shift (more to less) 9 10 Decrease pressure: shift (less to more) 9 10 4 NH (g) + 5 O 2 (g) 4 NO (g) + 6 H 2 O (g) = gas molecules = gas molecules Increase pressure: shift (more to less) 9 10 Decrease pressure: shift (less to more) 9 10
  • Slide 25
  • N 2 + 3 H 2 2 NH 3 Equilibrium shift [N 2 ] [H 2 ] [NH 3 ] # molecules: Increased pressure shifts towards fewer molecules Decreased pressure shifts towards more molecules
  • Slide 26
  • H 2 + I 2 2 HI Equilibrium shift [H 2 ] [I 2 ] [HI] # molecules: Increased pressure shifts towards fewer molecules Decreased pressure shifts towards more molecules
  • Slide 27
  • Conclusion Questions 1. How does a system at equilibrium respond to a stress? List the factors that can be stresses on an equilibrium system.
  • Slide 28
  • Conclusion Questions 2. Given the reaction at equilibrium: N 2 (g) + 3 H 2 (g) 2 NH 2 (g) + heat Which stress would cause the equilibrium to shift to the left? (a) Increasing the temperature (b) Adding N 2 (g) to the system (c) Adding H 2 (g) to the system 2. Given the reaction at equilibrium: N 2 (g) + 3 H 2 (g) 2 NH 2 (g) + heat Which stress would cause the equilibrium to shift to the left? (a) Increasing the temperature (b) Adding N 2 (g) to the system (c) Adding H 2 (g) to the system
  • Slide 29
  • Conclusion Questions 2. Given the reaction at equilibrium: N 2 (g) + O 2 (g) 2 NO (g) If the concentration of N 2 (g) is increased, the concentration of O 2 (g) will (a) Decrease (b) Remain the same (c) Increase 2. Given the reaction at equilibrium: N 2 (g) + O 2 (g) 2 NO (g) If the concentration of N 2 (g) is increased, the concentration of O 2 (g) will (a) Decrease (b) Remain the same (c) Increase