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Exam III Thursday, December 6, 7:00-9:00 pm; rooms are on the website (same as Exam II). Conflict: (12/6) 4:30-6:30 pm in 219 Greg; sign up in 1026 Chem Annex starting Friday Conflict with conflict? Email me right away. Review sessions: 1024 Chem Annex, 6-8 pm Monday, December 3 Tuesday, December 4

Clicker Questions Pure N2O3 was placed in a rigid vessel and allowed to decompose: 2N2O3(g)  2N2(g) + 3O2(g). The following data were collected in an experiment at a certain temperature. Determine: the rate law of the reaction. the first half-life for the reaction the pressure of O2(g) at t = 25.00 minutes Time (min) Ptotal (atm) 10.000 10.00 15.071 20.00 18.428 30.00 20.649 40.00 22.120 50.00 23.094

Rate Laws From Elementary Steps

Clicker Question The experimental rate law for the decomposition of nitrous oxide (N2O) to N2 and O2 is rate = k[N2O]2. Two mechanisms are proposed: I. N2O  N2 + O N2O + O  N2 + O2 II. 2N2O N4O2 N4O2  2N2 + O2 Which of the following could be a correct mechanism? a) Mechanism I with the first step as the rate-determining step. b) Mechanism I with the second step as the rate-determining step as long as the first step is a fast equilibrium step. c) Mechanism II with the second step as the rate-determining step if the first step is a fast equilibrium step. d) None of the choices (a-c) could be correct. e) At least two of the above choices (a-c) could be correct.

Chapter 15

Pseudo-Order Question Determine the rate law and value of k given the following data. 2H2(g) + 2NO(g)  N2(g) + 2H2O(g) EXPERIMENT #1 EXPERIMENT #2 TIME (sec) [NO] [NO] ________ 0 1.00 x 10-2 M 1.00 x 10-2 M 10.0 6.67 x 10-3M 5.00 x 10-3 M 20.0 5.00 x 10-3 M 3.33 x 10-3 M 30.0 4.00 x 10-3 M 2.50 x 10-3 M 40.0 3.33 x 10-3 M 2.00 x 10-3 M   In experiment #1, [H2]0 = 10.0 M In experiment #2, [H2]0 = 20.0 M