Catalyst

1. Take out your HW! Catalyst • Objectives • I can define Le Chatelier’s principle. • I can describe factors that shift chemical equilibrium. • Agenda • Catalyst • Homework Review • Unit 9 Stations • Exit Slip: Le Chatelier’s Principle What are the five factors or conditions that affect the rate of a chemical reaction? What are the three factors that may shift the position of chemical equilibrium? What is due this Wednesday in Chemistry class?

2. Exit Slip Review • Assignment: 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. • Sample Answer: Chemical equilibrium is a state of balance in which the rate of a forward reaction equals the rate of the reverse reaction. At equilibrium, the concentrations of the reactants and products stop changing. However, the amount of reactant and product may not be equal. Chemical equilibrium involves reversible reactions that proceed in both the forward and reverse direction. A completion reaction does not go to equilibrium because all of the reactants turn into products. This is called going to “completion”. In the bucket equilibrium demonstration, the system ended up at equilibrium because the amount of water transferred either way became the same.

3. Exit Slip Review Continued • This student paragraph received a 4: A chemical equilibrium is when a chemical or substance equals out or moves at the same rate. A reversible reaction is when the products and reactants can switch or reverse the opposite way. A completion reaction is when they only move forward. When they move at the same rate it will reach a equilibrium. For example, in the water demonstration, one started out with a lot of water and the other didn’t. Since they were moving at the same rate, they reached equilibrium.

4. 9b Make Up Assignment • pp. 522 #20 – Answer and justify your answer. • Correct and then write a final draft of your chemical equilibrium paragraph.

5. HW: pp. 518 #2, 3, 9; pp. 522 #18 &19 #2) Chemical equilibrium responds to the following stresses: changes in pressure, changes in temperature, and changes in concentration of reactants or products. 3) Adding extra reactant shift the equilibrium to the right. Adding extra product shifts the equilibrium to the left. • Yes, doubling the pressure causes the volume to be cut in half. This results in double the concentration of all products and reactants. Then the equilibrium will shift towards the side with less gas. • You could use an analogy to explain Le Chatelier’s principle such as a balance.

6. HW continued #19 H2 (g) + Cl2 (g) çè 2HCl (g) + 184 KJ • Add Cl2 – forward • Remove HCl – forward • Increase pressure - neither • Decrease temperature – forward • Remove H2 – reverse • Decrease pressure – neither • Increase temperature – reverse • Decrease volume - neither

7. Reaction Rate/Equilibrium Stations • Expectations: • You must work record all your work on your own sheet of paper. • You must cooperate with your table group mates to share materials and work quickly but carefully. • You may speak quietly with your group members about your work. • You will have about 20 minutes at each station. If you finish early, work on any reaction rate or equilibrium worksheet, HW, or DWO challenge material. • The Stations: • Station 1: True/False Strips • Station 2: What’s so Equal about Equilibrium? (Article) • Station 3: Le Chatelier’s Principle Balancing Game

8. 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: • Complete any worksheets or article questions that you have not finished.