1. Question of the Day For a reaction involving a single reactant, the following data were obtained. Day 2 4-15 Determine the order of the reaction. Either show work or explain!

2. Question of the Day Does an oreo get soggy quicker in milk or a milkshake? Explain the difference in reaction rate in terms of one of the four factors influencing reaction rates (BE SPECIFIC!) Day 3 4-16

4. http://wps.prenhall.com /esm_brown_chemistry_ 9/2/660/169060.cw/inde x.html Homework # 2 Chapter 14 – w/ discussion partner – show me successful screen (100%) # 7 = the reaction rate would quadruple.  doubling the partial pressure is the same as doubling the concentration.

5. Question of the Day The following data were collected for the rate of disappearance of NO in the reaction: 2NO (g) + O 2(g)  2NO 2(g) Write the rate law for this equation: _______________________ Solve for k: What are the units for k? Day 5 4-22

6. Rxn Mechanisms & Rate-Determining Steps A.A reaction mechanism is a series of ____________ that lead to a net reaction. B.Reaction mechanisms can have _____________ steps. C.Parts of mechanisms 1.Net reaction is _________ simple rxns one or more the goal

7. Rxn Mechanisms & Rate-Determining Steps C.Parts of mechanisms 1.Net reaction is __________ 2.Elementary step is one of the __________ in the ________ 3.Intermediate product is a product that is made by _______________ _____ that becomes a _________ in a subsequent ________________ the goal reactionsprocess an elementary step reactant elementary step

8. Rxn Mechanisms & Rate-Determining Steps C.Parts of mechanisms 4.Catalyst is a substance that first appears as a _________ in one ________________ and then becomes a ________ in a subsequent ________________ reactant elementary step product elementary step

9. Reaction mechanisms that have multiple steps have one step that is the rate-determining step. The rate- determining step is the step that is the _______ of all the steps. Rxn Mechanisms & Rate-Determining Steps slowest

10. Postlabs are due on Wednesday 4-23 Lab reports and presentations are due Friday 4-25

11. E.Write several mechanisms and identify any intermediates and catalysts. 1.1-step mechanism for reaction of calcium oxide with water Rxn Mechanisms & Rate-Determining Steps

12. Question of the Day Day 6 4-23 Describe how intermediates, activated complexes, and catalysts are different (thoroughly!).

13. http://wps.prenhall.com /esm_brown_chemistry_ 9/2/660/169060.cw/inde x.html Homework # 2 Chapter 14 – w/ discussion partner – show me successful screen (100%) # 7 = the reaction rate would quadruple.  doubling the partial pressure is the same as doubling the concentration.

14. E.Write several mechanisms and identify any intermediates and catalysts. 2.2-step mechanism for rxn of NO 2 with CO to produce NO and CO 2 (all gases) Rxn Mechanisms & Rate-Determining Steps NO 2 + NO 2  NO 3 + NO NO 3 + CO  NO 2 + CO 2 slow fast NO 2 + CO  NO + CO 2 net Period 1 stopped 4-22

15. 2.2-step mechanism for rxn of NO 2 with CO to produce NO and CO 2 (all gases) Rxn Mechanisms & Rate-Determining Steps NO 2 + NO 2  NO 3 + NO NO 3 + CO  NO 2 + CO 2 slow fast NO 2 + CO  NO + CO 2 net Intermediate =NO 3

16. E.Write several mechanisms and identify any intermediates and catalysts. 3.3-step mechanism for the rxn of HBr with O 2 to produce H 2 O and Br 2 (all gases) Rxn Mechanisms & Rate-Determining Steps HBr + O 2  HOOBr HBr + HOOBr  2 HOBr 2 HBr + 2 HOBr  2 H 2 O + 2 Br 2 4 HBr + O 2  2 H 2 O + 2 Br 2

17. 3.3-step mechanism for the rxn of HBr with O 2 to produce H 2 O and Br 2 (all gases) Rxn Mechanisms & Rate-Determining Steps HBr + O 2  HOOBr HBr + HOOBr  2 HOBr 2 HBr + 2 HOBr  2 H 2 O + 2 Br 2 4 HBr + O 2  2 H 2 O + 2 Br 2 Intermediates = HOOBr and HOBr

18. 4.Write the net rxn for the following 2-step mechanism. NO 2(g) + SO 2(g) → NO (g) + SO 3(g) 2 NO (g) + O 2(g) → 2 NO 2(g) Rxn Mechanisms & Rate-Determining Steps

19. Review Analyze the following reaction mechanism: step 1: N 2 O  N 2 + O step 2: N 2 O + O  N 2 + O 2 What is the net reaction? Are there any intermediates and/or catalysts present?

20. Equilibrium Equilibrium occurs when the forward and reverse reactions occur at equal rates – NOT a standstill!

21. Equilibrium A. Physical Equilibrium Example 1. H 2 O (l) ⇄ H 2 O (g) 2. Appearance of system Rate of Evap. = Rate of Cond. To regular eyes: Looks as if nothing is happening But on the molecular level: 2 rxns or  s occur simultaneously

22. B.Chemical Reaction Options 1. Rxn goes to completion  products stay & reaction stops; Ex : burning 2. No go : He + Ne  no rxn 3. Rxn reaches equilibrium = get a set amount of reactants & products coexisting C.Main Concern of Equilibrium Calculations 1. How FAR will the reaction go? 2. How much product can be made? Equilibrium

23. D. What conditions must be met to attain equilibrium? –Constant T & P –Closed container –  G = 0 Equilibrium

24. E. Example equilibrium system and experimental data: 2 HI (g) ⇄ I 2(g) + H 2(g) [HI][I 2 ][H 2 ] → [HI][I 2 ][H 2 ] Exp #10.200 → Exp #2 00.1 → Exp #3 0.1 → 0.160.020.02 0.160.020.02 0.240.030.03 Equilibrium

25. What happened to the concentrations of each substance during the experiments? –Exp #1 & #2 Changed to form chemicals not present at the start of the reaction –Exp #3 Changed to form more of the “favored” chemicals Equilibrium

26. C.Example of system reaching equilibrium N 2 O 4(g) ⇄ 2 NO 2(g) at 100 °C Time (s)020406080100 [N 2 O 4 ]0.1000.0700.0500.040 [NO 2 ]0.0000.0600.1000.120 Equilibrium

28. Stopped on 4-2

29. Assignment: Review section 18.2 and complete #s 9- 16 on page 608.

31. Period # 1 LAB

32. http://chemconnections.org/Java/equilibriu m/index.html http://www.chem.iastate.edu/group/Greenbo we/sections/projectfolder/animations/equilv pBr2V8.html Equilibrium