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Catalyst

Take out your HW!. Catalyst. Objectives I can define chemical equilibrium and identify systems that are in chemical equilibrium . I can investigate factors that shift chemical equilibrium. Agenda Catalyst What is Equilibrium? Demonstration & Simulations: Equilibrium Exit Slip.

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Catalyst

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  1. Take out your HW! Catalyst • Objectives • I can define chemical equilibrium and identify systems that are in chemical equilibrium. • I can investigate factors that shift chemical equilibrium. • . • Agenda • Catalyst • What is Equilibrium? • Demonstration & Simulations:Equilibrium • Exit Slip What does “reversible” mean? Give examples of a reversible physical or chemical process.

  2. Start Up: Think Box • Take 1 minute to write as many things as you can think of in the box at the top of your Notes Day 3 worksheet. • When you think of the word EQUILIBRIUM, what do you think of?

  3. Definition of equilibrium • Using the scenarios we just wrote down, what is a possible definition of equilibrium. • Put it in your own words, write down how YOU would define equilibrium… • Your definition does not have to sound scientific • Equilibrium is the exact balancing of two processes, one of which is opposite of the other. • Equilibrium implies “balance” or “steadiness”

  4. What is chemical equilibrium? • Chemical equilibrium is a state of balance in which the rate of a forward reaction equals the rate of the reverse reaction and the concentrations of the products and reactants remain unchanged.

  5. Check for Understanding • Hold up a 1 for forward and a 2 for reverse. • Which reaction rate is faster (higher) at time 2 min?

  6. Check for Understanding • Hold up the number of fingers corresponding to the time at which the reaction first reaches equilibrium.

  7. Check for Understanding • Hold up the number of fingers to answer: • What is the reaction rate at equilibrium?

  8. Completion Reaction vs. Reversible Reaction

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

  10. White Board Practice • PCl5 PCl3 + Cl2 • Is this a completion reaction or a reversible reaction? How do you know?

  11. White Board Practice • PCl5 PCl3 + Cl2 • Write the forward reaction: • Write the reverse reaction:

  12. White Board Practice • 2 H2(g) + O2(g) → 2 H2O (l) • Is this a completion reaction or a reversible reaction? How do you know? • Label the reactants and the products.

  13. Quick Check • Hold up a number according to the following scale: • 1 = I need lots more help! • 2 = I have the basics and can work with a partner. • 3 = I am able to work on my own. • 4 = I could teach the class.

  14. Demonstrations: Chemical Equilibrium • Listen and watch carefully during the demonstrations. • Answer the questions on your worksheet as we go.

  15. Demonstration 1: • What is equilibrium? (There are two containers. Container A has more water than container B. A student uses a large beaker to transfer water from A to B. At the same time, a student uses a small beaker to transfer water from B to A.) • 1. Prediction: What will eventually happen to the amounts of water in each container? • 2. Prediction: What will eventually happen to the amounts of water being transferred each direction? • As the demonstration is going, answer problems 3 and 4. • After the demonstration work with a partner to complete 5 and 6.

  16. Let’s Go Over It… • 5. What do each of the following represent in terms of a reversible reaction? • _ The amount of water in container A • _ The amount of water in container B • _ The amount of water transferred from A to B • _ The amount of water transferred from B to A • 6. What does this demonstration show about a reaction that is at equilibrium?

  17. Let’s Go Over It… • 5. What do each of the following represent in terms of a reversible reaction? • _ The amount of water in container A – Reactant Concentration • _ The amount of water in container B – Product Concentration • _ The amount of water transferred from A to B – Forward Reaction Rate • _ The amount of water transferred from B to A – Reverse Reaction Rate • 6. What does this demonstration show about a reaction that is at equilibrium? The amount of reactant and product do not have to be the same. Rather, the amount of reactant and product stop changing when the rate of the forward and reverse reactions are equal.

  18. Demonstration 2 • (There are two containers. Container B has more water than container A. A student uses a large beaker to transfer water from A to B. At the same time, a student uses a small beaker to transfer water from B to A.) • 7. Before the demo: Make a prediction – what do you think will happen? • 8. After the demo: What was similar and what was different about the demonstration when we started with a smaller amount in container A? Why did the reaction behave this way?

  19. Check For Understanding: Summing it Up! At Equilibrium… • HCl + NaOH H2O + NaCl • At equilibrium the concentrations of products and reactants are (1 – changing/ 2 - not changing) • The forward reaction is happening (1 - at the same time as/ 2 – after) the reverse reaction • We say that the forward rate is (1 – greater than/ 2 - the same as) the reverse rate • This means the amounts of products and reactants (1 – are equal/ 2 – does not change)

  20. Demonstration 3 and 4: Computer Simulations • With a partner, pick up a laptop. Open the internet and type in: http://tinyurl.com/boonchem12 • Click “run now” to open the simulation • Carefully observe the simulation. Take notes and answer questions on your handout.

  21. Simulation 3 & 4 Set Up • Open the simulation. Set the gray energy level bars for A and B equal to one another. In this simulation, you will add 75 molecules to “A” and observe what happens. • Before adding the molecules, answer question #9. • Observe the simulation for at least 2 min. or until the reaction comes to equilibrium. Then, answer questions #10 and #11. • Simulation #4: Reset the simulation by changing the number of molecules to zero. Then, move the gray energy bar for “A” and the ruler up to between 20 and 40. • Before adding 75 molecules to A, answer question #12. • Observe the simulation for at least 2 min. or until the reaction comes to equilibrium. Then, answer questions #13. • Add heat, observe, and answer question #14. Add molecules to “B”, observe, and answer #15.

  22. Vocabulary Practice • On your iPad practice your Reaction rates and equilibrium vocabulary with the following games: • BrainRush Reaction Rates sorting game: http://tinyurl.com/boonchem13 • Quizlet Equilibrium Vocabulary Flashcards: http://tinyurl.com/boonchem14 • Challenge: If you are confident with vocabulary, try this Advanced assignment on calculating reaction rates: P. 576-581, p. 581 #1-3

  23. http://tinyurl.com/boonchem11 • Exit Slip Expectations: • You will work silently and independently. • When you are done, cover your exit slip with your handouts. • Tools: • You may use all your notes, worksheets, and flash cards. • You may use your own calculator. • What do I turn in? • You will turn in your exit slip only. • Homework: • pp. 496-501 problems pp. 501 #1-3, 6, 7

  24. Homework • Homework: • pp. 496-501 problems pp. 501 #1-3, 6, 7

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