Understanding Le Chatelier's Principle and Equilibrium Shifts

1. 53 Days Until the Harvard Westlake Final Catalyst: • Define what equilibrium is using the rate of the forward reaction and the rate of the reverse reaction. • What is activation energy?Label it on a reaction coordinate. 3. How is a catalyst related to activation energy? End

3. The Briggs-Rauscher Reaction IO3− + 2H2O2 + CH2(COOH)2 + H+ ⇌ ICH(COOH)2 + 2O2 + 3H2O Amber Color Navy Blue Color

4. Justify – TPS • Why did the reaction keep changing colors?

5. LECTURE 8.4 – LE CHATELIER’S PRINCIPLE

6. Today’s Learning Target • LT 8.7 – I can define Le Chatelier’s principle and use this principle to predict how concentration, temperature, and pressure will impact a given equilibrium.

7. What is Le Chatelier’s Principle?

8. Le Chatelier’s Principle “If a system at equilibrium is disturbed by a change in temperature, pressure, or concentration, the system will shift its equilibrium position so as to counteract the effect of the stress.” If equilibriums are disturbed, it will shift to restore that equilibrium.

9. How do concentration, pressure, and temperature impact equilibrium?

10. Le Chatelier’s Principle and Concentration If we add more of a product/reactant, then our reaction will shift to the other side in order to compensate for this new amount.

11. Class Example • I have the following equilibrium: H2O ⇌ H3O+ + OH- • If I add H3O+, then will my reaction shift to the right or to the left?

12. Table Talk • I have the following equilibrium: CaCO3 ⇌ CaO + CO2 • If I add CaCO3, then will my reaction shift to the right or to the left?

13. Le Chatelier’s Principle and Volume/Pressure If we increase pressure, the reaction shifts to the side with less molecules If we decrease pressure, the reaction shifts to the side with more molecules

14. Class Example • I have the following equilibrium: N2 (g) + 3H2 (g) ⇌ 2NH3 (g) • If I increase the pressure, then will my reaction shift to the right or to the left?

15. Table Talk • I have the following equilibrium: CaCO3 ⇌ CaO + CO2 • If I decrease pressure, then will my reaction shift to the right or to the left?

16. Le Chatelier’s Principle and Temperature When a reaction is endothermic, heat is listed as a reactant. Heat + Reactants  Products When a reaction is exothermic, heat is listed as a product. Reactants  Products + Heat Therefore, treat heat like a reactant or a product

17. Class Example • I have the following equilibrium: N2 (g) + 3H2 (g) ⇌ 2NH3 (g) + 92 kJ • If I increase the temperature, then will my reaction shift to the right or to the left?

18. Table Talk • I have the following equilibrium: 556 kJ + CaCO3 (s) ⇌ CaO (s) + CO2 (g) • If I decrease the temperature, then will my reaction shift to the right or to the left?

19. Use the following words: • Le Chatelier • Concentration • Pressure • Temperature • Stress Summarize

20. White Board Questions • State whether it will shift to the left, right, or stay the same based on the given conditions NaOH (aq) + HCl (aq)  NaCl (s) + H2O (l) • Add HCl • Remove NaOH • Add NaCl • React NaOH with HNO3

21. White Board Questions • State whether it will shift to the left, right, or stay the same based on the given conditions 4HCl (g)+ O2 (g)  2H2O(g) + 2Cl2 (g)+ 113 kJ • Increase pressure • Decrease temperature • Add H2O • Remove O2 • Add HCl

22. White Board Questions • State whether it will shift to the left, right, or stay the same based on the given conditions NaCl (aq)  Na+ (aq) + Cl- (aq) + 426 kJ • Decrease the temperature • Add Na+ • Remove Cl- • Add HCl (think about what the compound contains)

23. Screencast-o-matic • Today, students get to the be the teacher! • You will have an opportunity to teach the world how Le Chatelier’s Principle works by using screencast-o-matic to solve problems involving Le Chatelier’s Principle and record them.

25. Closing Time • Wikispaces! • Screencast-o-matic! • ACS Chemistry Olympiad! • Unit 8 Exam!