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Catalyst

Catalyst. Objectives I can define Le Chatelier’s principle. I can describe factors that shift chemical equilibrium. Agenda Catalyst Video Investigation: Equilibrium Le Chatelier’s Principle Exit Slip.

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Catalyst

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  1. Catalyst • Objectives • I can define Le Chatelier’s principle. • I can describe factors that shift chemical equilibrium. • Agenda • Catalyst • Video Investigation: Equilibrium • LeChatelier’s Principle • Exit Slip Pick up a whiteboard and marker and complete the following benchmark review question: If each of these flasks has the same number of gas molecules inside, which one has the lowest pressure? (a) Flask 1 (c) Flask 2 (b) Flask 3 (d) Flask 4

  2. Video Investigation: Dynamic Equilibrium • Answer the following questions on a white board: • What is dynamic equilibrium? • Explain the example of dynamic equilibrium in the video. • Can you come up with your own example?

  3. What is Le Chatelier’s Principle? • For a reversible process at equilibrium, when conditions of concentration, temperature, or pressure are changed, the reaction shifts in a direction that will counteract the stress and restore equilibrium.

  4. Think Box: In my own words. • First, watch the video explain Le Chatelier’s Principle. • Rewrite Le Chatelier’s Principle in your own words. • You will have 2 minutes to write on your own. • You will have 2 minutes to discuss with the person next to you and revise your work. In an equilibrium system, when there is a change in conditions, the equilibrium will shift to counteract or undo the change.

  5. add reactants or take away products causes shift to the right (forward) • add product or take away reactants causes shift to the left (reverse) • increase temp causes shift to endothermic side • decrease temp cause shift to exothermic side • increase pressure causes shift to less moles of gas • decrease pressure causes shift to more moles of gas

  6. What will undo the change? How does Le Chatelier’s Principle work? Example #1: N2(g) + 3H2(g) ↔ 2NH3(g) + heat Left / reverse To remove the extra heat Right/ forward To replace the lost heat Right/ forward To decrease the extra reactant Left / reverse To decrease the extra product Right/ forward To decrease the moles of gas Left / reverse To increase the moles of gas

  7. What will undo the change? • Example #2: N2O4(g) + heat ↔ 2NO2(g) Right/ forward To remove the extra heat Left / reverse To replace the lost heat Right/ forward To decrease the extra reactant Left / reverse To decrease the extra product Left / reverse To decrease the moles of gas Right/ forward To increase the moles of gas

  8. Check for Understanding • Compare the charts for example 1 and 2 in your notes. Why does increasing the temperature cause different shifts in equilibrium? • (1) The affect of changing temperature is random. • (2) The shift is to the left for endothermic reactions and to the right for exothermic reactions. • (3) The shift is to the right for endothermic reactions and to the left for exothermic reactions.

  9. Check for Understanding • Compare the charts for example 1 and 2 in your notes. Why does increasing the pressure cause different shifts in equilibrium? • (1) The affect of changing pressure is random. • (2) The shift is to the side with less moles of gas to counteract the increase in pressure. • (3) The shift is to the side with more moles of gas to counteract the increase in pressure.

  10. White Board Practice • Instructions: • Write your answer on your white board. • When Ms. Boon says go, hold up your white board.

  11. Answer the question as you watch the video… • List all reversible processes that you saw in the video. What caused the processes to continue or change directions?

  12. White Board Practice • PCl5 PCl3 + Cl2 • In order to shift the equilibrium to the right, the rate of the _____________________________ reaction will increase. • In order to shift the equilibrium to the left, the rate of the ___________________________ will increase.

  13. White Board Practice • PCl5 PCl3 + Cl2 • Adding more product shifts the equilibrium to the ___________. • Adding more product increases the rate of the ______________________________ reaction. • Taking away some of reactant shifts the equilibrium to the _________________.

  14. White Board Practice • 2 H2(g) + O2(g) ↔2 H2O (g) • Taking away some H2 will increase the rate of the _______________ reaction. • Decreasing the pressure will shift the equilibrium to the ________.

  15. White Board Practice • 6CO2 + 6H2O + 12 kJ  C6H12O6 + 6CO2 • Increasing the temperature will increase the rate of the __________________ reaction. • Increasing the temperature shifts the equilibrium to the ____________________.

  16. Catalyst • Objectives • I can define Le Chatelier’s principle. • I can describe factors that shift chemical equilibrium. • Agenda • Catalyst • Video Investigation: Equilibrium • LeChatelier’s Principle • Exit Slip Find your folder and your returned Chemistry work. Take about 4 minutes to organize your folder for student led conferences. Put the most recent items on the top. Pass in your homework - The article questions.

  17. Le Chatelier’s Principle Video Demo • Answer the following questions on the back of your notes handout. • Copy the chemical reaction equation for the synthesis of thiocyanatoiron: Fe3+(aq) + SCN-(aq) ↔ [Fe(SCN)]2+(aq) [Fe(SCN)]2+ is a red-orange color. Fe3+ is pale yellow and SCN- is colorless. • Use Le Chatelier’s principle to predict how the color will change if more reactants are added. Why? • Use Le Chatelier’s principle to predict how the color will change if some reactants are taken away. Why?

  18. Independent Practice • Assignment: • Choice 1: Complete all Reactions Rates & Equilibrium handouts and book HW. (Basic or Beginner Choice) • Choice 2: Equilibrium Article and questions (Proficient or Intermediate) • Choice 3: Challenge Assignment (Gibbs Free Energy or Calculating Reaction Rates – See “Challenge Zone” For page numbers). Homework: Read pp. 512- 518, pp. 518 #1, 2, 3,6, 9; pp. 522 #18, 19, 20, 21, 23 • Expectations: • You may work with the person next to you. • You will use respectful academic language and speak at a noise level at which only people next to or across from you can hear.

  19. Exit Slip: http://tinyurl.com/boonchem15 • Part 1: • Write at least 5 sentences explaining what chemical equilibrium is. Use examples from class. Use the key terms: reversible reaction, completion reaction, and chemical equilibrium. • Part 2: • Grade your level of understanding of the current unit on a scale of 1 – 4. 4 is the highest. • Homework: • HW: Read pp. 512- 518, pp. 518 #1, 2, 3,6, 9; pp. 522 #18, 19, 20, 21, 23

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