1 / 33

Equilibrium

Equilibrium. Review Lab Reports. Objective/Warm-Up. SWBAT describe equilibrium and determine shifts based on Le Chatelier’s principle. What does the word “equilibrium” mean to you?. Chemical Equilibrium. Chemical equilibrium:

george
Download Presentation

Equilibrium

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Equilibrium

  2. Review Lab Reports

  3. Objective/Warm-Up • SWBAT describe equilibrium and determine shifts based on Le Chatelier’s principle. • What does the word “equilibrium” mean to you?

  4. Chemical Equilibrium • Chemical equilibrium: • Rate of forward reaction (reactants to products) = rate of reverse reaction (products decomposing to reactants)

  5. Reversible Reactions • The conversion of reactants into products and the conversion of products into reactants occur simultaneously. • Example: 2SO2 + O22SO3

  6. N2 (g) + 3 H2 (g) 2 NH3 (g) Chemical Equilibrium • chemical equilibrium is best represented with a double arrow: • The double arrow is used to indicate that the reaction is an equilibrium reaction. • It indicates that the reaction occurs in both directions simultaneously.

  7. Equilibrium • At equilibrium, the forward and reverse reaction rates are equal. • The concentrations of reactants and products stop changing. • This does NOT mean that the concentrations are equal.

  8. Equilibrium Expressions • Guided Inquiry worksheet

  9. Writing Equilibrium Constants • aA + bB  cC + dD • Keq = [C]c x [D]d [A]a x [B]b • The brackets indicate the concentration in molarity.

  10. Write the Equilibrium Constant • N2O4 2NO2 • H2 + I2  2HI • 3H2 + N2  2NH3 • 2BrCl  Cl2 + Br2

  11. Magnitude of Equilibrium Constants • When Kc (or Kp or Ksp) < 1, more reactants than products are present at equilibrium. N2 (g) + O2 (g) 2 NO (g) Kc = [NO]2 = 1 x 10-30 [N2] [O2] • Equilibrium lies to the left. • Reactants are favored.

  12. Magnitude of Equilibrium Constants • When Kc (or Kp or Ksp) is > 1, more products than reactants are present at equilibrium. CO (g) + Cl2 (g) COCl2 (g) Kc = [COCl2] = 4.57 x 109 [CO] [Cl2] • Equilibrium lies to the right. • Products are favored.

  13. Chemical Equilibrium • CO2 (g) + H2 (g) CO (g) + H2O (l) If a solid or liquid is involved, its concentration is constant and in not included in the equilibrium constant expression. • For this example: Kc = [CO] [CO2][H2]

  14. Calculating Keq 2CO (g) ↔ C (s) + CO2 (g) [CO] = 0.034M [CO2 ] = 0.0045M What is the value of Keq ? Ans: 3.89

  15. N2O4 (g) ↔ 2NO2 (g) [N2O4 ] = 2.0M [NO2 ] = 0.2M What is the value of Keq ? Ans: 0.02

  16. 2ICl (g) ↔ I2 (g) + Cl2 (g) [ICl ] = 2.5 M [I2] = 2.0 M [Cl2] = 1.2 M What is the value of Keq ? Ans: 0.384

  17. Objective/Warm-Up • SWBAT apply LeChatelier’s principle and solve equilibrium problems. • How do you know a reaction is at equilibrium? • Write the equilibrium expression: • 2ICl (g) ↔ I2 (g) + Cl2 (g)

  18. LeChatelier’s Principle • When a stress is applied to a system, the system will try to relieve that stress.

  19. Le Chatelier’s Principle • http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/lechv17.swf • http://www.chm.davidson.edu/java/LeChatelier/LeChatelier.html • http://virtual.yosemite.cc.ca.us/smurov/ex14-1.htm

  20. Practice

  21. Q vs. K • http://www.yteach.com/page.php/resources/view_all?id=equilibrium_concentration_Le_Chatelier_dimerisation_oxide_temperature_catalyst_page_0&from=search

  22. Objective/Warm-Up • SWBAT apply LeChatelier’s principle and solve equilibrium problems. • N2O4 (g) 2NO2 (g) • Which way will the above reaction shift if: • More NO2 is added • N2O4 is removed • Pressure is increased

  23. Le Chatelier’s Principle • http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/lechv17.swf • http://www.chm.davidson.edu/java/LeChatelier/LeChatelier.html • http://virtual.yosemite.cc.ca.us/smurov/ex14-1.htm

  24. Video

  25. Objective/Warm-Up • SWBAT apply LeChatelier’s principle and solve equilibrium problems. • N2O4 (g) 2NO2 (g) • Which way will the above reaction shift if: • More NO2 is added • N2O4 is removed • Pressure is increased

  26. Objective/Warm-Up • SWBAT apply LeChatelier’s principle and solve equilibrium problems. • Which way will the system shift? • As4O6 (s) + 6 C (s) As4 (g) + 6 CO (g) • Addition of carbon monoxide • Addition of carbon • Removal of carbon • Addition of As4O6 • Removal of As4O6 • Removal of As4

  27. Summary of Le Chatelier’s principle • Amounts of products and reactants: equilibrium shifts to compensate • N2  H2 E.g. N2 + 3H2 2 NH3 + 92 kJ N2 + 3H2 2NH3 + 92 kJ shift right N2 + 3H2 2NH3 + 92 kJ N2 + 3H2 2NH3 + 92 kJ N2 + 3H2 2NH3 + 92 kJ shift left N2 + 3H2 2NH3 + 92 kJ N2 + 3H2 2NH3 + 92 kJ Temperature: equilibrium shifts to compensate:  Heat N2 + 3H2 2NH3 + 92 kJ shift left N2 + 3H2 2NH3 + 92 kJ N2 + 3H2 2NH3 + 92 kJ Pressure (due to decreased volume): increase in pressure favors side with fewer molecules Catalysts: does not influence reaction

  28. Equilibrium of Fish

  29. http://www.yteach.com/page.php/resources/view_all?id=equilibrium_concentration_Le_Chatelier_dimerisation_oxide_temperature_catalyst_page_2&from=searchhttp://www.yteach.com/page.php/resources/view_all?id=equilibrium_concentration_Le_Chatelier_dimerisation_oxide_temperature_catalyst_page_2&from=search

  30. Practice

  31. Group Activity • In groups of 4 people, choose an equilibrium reaction and represent it to the class in some way (poem, skit, song, dance, role play, etc.). • All group members must participate. • Use of props is recommended. • You must include three disturbances and explain their corresponding shifts according to Le Chatelier’s principle.

More Related