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Approaching Equilibrium Lesson 1

Approaching Equilibrium Lesson 1. Approaching Equilibrium Many chemical reactions are reversible if the activation energy is low. Reactants ⇌ Products. Approaching Equilibrium Many chemical reactions are reversible if the activation energy is low. Reactants ⇌ Products

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Approaching Equilibrium Lesson 1

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  1. Approaching Equilibrium Lesson 1

  2. Approaching Equilibrium Many chemical reactions are reversible if the activation energy is low. Reactants⇌Products

  3. Approaching Equilibrium Many chemical reactions are reversible if the activation energy is low. Reactants⇌Products Always on left Always on right

  4. Approaching Equilibrium Many chemical reactions are reversible if the activation energy is low. Reactants⇌Products

  5. Approaching Equilibrium Many chemical reactions are reversible if the activation energy is low. Reactants⇌Products Forward Rate is from left to right

  6. Approaching Equilibrium Many chemical reactions are reversible if the activation energy is low. Reactants⇌Products Reverse Rate is from right to left

  7. Lets see what happens to some reactants if they are placed in a reaction vessel and allowed to react.

  8. Approaching Equilibrium Products Reactants Forward Rate Reverse Rate

  9. Approaching Equilibrium Products Reactants Forward Rate Reverse Rate

  10. Approaching Equilibrium Products Reactants Forward Rate Reverse Rate

  11. Approaching Equilibrium Products Reactants Forward Rate Reverse Rate

  12. Approaching Equilibrium Products Reactants Forward Rate Reverse Rate

  13. Approaching Equilibrium Products Reactants Forward Rate Reverse Rate

  14. Approaching Equilibrium Products Reactants Forward Rate Reverse Rate

  15. Approaching Equilibrium Products Reactants Forward Rate Reverse Rate Are Equal

  16. Approaching Equilibrium Products Reactants Forward Rate Reverse Rate Are Equal Are Constant

  17. Approaching Equilibrium from Products Products Reactants Forward Rate Reverse Rate Are Equal Are Constant Same as before

  18. Time [Reactant] Forward Rate [Product] Reverse Rate NetRate 0 8000 170 0 0 170 5 7500 160 1000 16 144 10 6800 145 2000 20 125 15  5600 120 2500 30 90 20 4600 100 3200 40 60 25 3600 84 4000 50 34 30 2900 75 4900 56 19 35 2000 65 6000 58 7 40 1600 60 6000 60 0 45 1600 60 6000 60 0 50 1600 60 6000 60 0

  19. Equilibrium has been attained after 40 minutes. The forward and reverse rates are equal and the reactant and productconcentrations are constant.

  20. Graph the [reactant] and [product] as equilibrium is approached. Concentration   8000 7000    6000 5000   4000 3000 2000 1000 0 15 30 Time equilibrium

  21. Graph the forward, reverse, & net rates as equilibrium is approached.  Rate   160 140    120 100   80 60 40 20 0 15 30 Time equilibrium

  22. Approaching Equilibrium Reactant concentrations start high and decreaseas the reaction proceeds. The forward rate, which depends on collisions of the reactants, also decreases. Product concentrations start at zero and increase as the reaction proceeds. The reverse rate, which depends on collisions of the products, also increases. Eventually the forward rate is equal to the reverse rate and the concentrations are constant. This is equilibrium.

  23. Characteristics of a System at Equilibrium The Forward rate = The Reverse rate The Reactant and Product concentrations are constant The Macroscopic (observable) properties are constant The system is Dynamic as the forward and reverse reactions continue. The equilibrium can be approached from starting with reactants or starting with products.

  24. Approaching Equilibrium from Products Products Reactants Forward Rate Reverse Rate

  25. Approaching Equilibrium from Products Products Reactants Forward Rate Reverse Rate

  26. Approaching Equilibrium from Products Products Reactants Forward Rate Reverse Rate

  27. Approaching Equilibrium from Products Products Reactants Forward Rate Reverse Rate

  28. Approaching Equilibrium from Products Products Reactants Forward Rate Reverse Rate

  29. Approaching Equilibrium from Products Products Reactants Forward Rate Reverse Rate Are Equal Are Constant Same as before

  30. If you start with products all aspects of the approach to equilibrium are reversed! Products and Reverse Rate decrease Reactants and Forward Rate increases

  31. Conditions Necessary for Equilibrium The system is closed. The temperature is constant. The Ea is low enough so that the reaction is reversible. Simulation1

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