1. AP Chemistry Chapter 14 Jeopardy Jennie L. Borders

2. Round 1 – Chapter 14

3. Rate Laws Half-LifeGraphingMechanisms Activation Energy Surprise 100 200 300 400 500

4. Rate Laws 100 Rate Laws 100 The reaction 2ClO 2 + 2OH -  ClO 3 - + ClO 2 - + H 2 O was studied with the following results: Determine the rate law for the reaction. Rate = k[ClO 2 ] 2 [OH - ] Experiment [ClO 2 ] (M) [OH - ] (M) Rate (M/s) 10.0600.0300.0248 20.0200.0300.00276 30.0200.0900.00828

5. Rate Laws 200 The reaction 2ClO 2 + 2OH -  ClO 3 - + ClO 2 - + H 2 O was studied with the following results: Calculate the rate constant. 229.63 M -2 s -1 Experiment [ClO 2 ] (M) [OH - ] (M) Rate (M/s) 10.0600.0300.0248 20.0200.0300.00276 30.0200.0900.00828

6. Rate Laws 300 The reaction 2ClO 2 + 2OH -  ClO 3 - + ClO 2 - + H 2 O was studied with the following results: Calculate the rate when [ClO 2 ] = 0.1M and [OH - ] = 0.05M. 0.115 M/s Experiment [ClO 2 ] (M) [OH - ] (M) Rate (M/s) 10.0600.0300.0248 20.0200.0300.00276 30.0200.0900.00828

7. Rate Laws 400 The following data was measured for the reaction BF 3 + NH 3  F 3 BNH 3 What is the rate law for the reaction? Rate = k[BF 3 ][NH 3 ] Experiment [BF 3 ] (M) [NH 3 ] (M) Initial Rate (M/s) 10.2500.2500.2130 20.2500.1250.1065 30.2000.1000.0682 40.3500.1000.1193 50.1750.1000.0596

8. Rate Laws 500 The following data was measured for the reaction BF 3 + NH 3  F 3 BNH 3 What is the rate when [BF 3 ] = 0.100M and [NH 3 ] = 0.500M? 0.1704 M/s Experiment [BF 3 ] (M) [NH 3 ] (M) Initial Rate (M/s) 10.2500.2500.2130 20.2500.1250.1065 30.2000.1000.0682 40.3500.1000.1193 50.1750.1000.0596

9. Half-Life 100 How do the half-lives of first-order and second-order reactions differ? Since the half-lives of first-order reactions are not based on initial concentration, then all the half-lives are equal. Since the half-lives of second-order reactions are based on initial concentrations, then each half- life is longer than the previous one.

10. Half-Life 200 The gas-phase decomposition of SO 2 Cl 2, SO 2 Cl 2  SO 2 + Cl 2, is first order in SO 2 Cl 2. At 320 o C the rate constant is 2.2 x 10 -5 s -1. What is the half-life at this temperature? 31,500s

11. Half-Life 300 Molecular iodine, I 2(g), dissociates into iodine atoms at 625K with a first- order rate constant of 0.271 s -1. What is the half-life of the reaction? 2.56s

12. Half-Life 400 Molecular iodine, I 2(g), dissociates into iodine atoms at 625K with a first-order rate constant of 0.271s -1. If you start with 0.050M I 2 at this temperature, how much will remain after 5.12s assuming that the iodine atoms do not recombine to form I 2 ? 0.012M

13. Half-Life 500 The first-order rate constant for the decomposition of N 2 O 5, 2N 2 O 5  4NO 2 + O 2, at 70 o C is 6.28 x 10 -3 s -1. What is the half-life of N 2 O 5 at 70 o C? 110.35s

14. Graphing 100 For a second-order reaction, what quantity, when graphed versus time, will yield a straight line? 1/[A]

15. Graphing 200 Consider the following data: Determine whether the reaction is first order or second order. First Order Time (s) 04080120160 Moles of A 0.1000.0670.0450.0300.020

16. Graphing 300 The gas-phase decomposition of NO 2, 2NO 2  2NO + O 2 is studied at 383 o C, given the following data: Is the reaction first order or second order with respect to the concentration of NO 2 ? Second Order Time (s) 0.05.010.015.020.0 [NO 2 ] (M) 0.1000.0170.0090.00620.0047

17. Graphing 400 At 23 o C and in 0.5M HCl, the following data was obtained for the disappearance of sucrose: Is the reaction first order or second order with respect to [C 12 H 22 O 11 ]? First Order Time (min) 03980140210 [C 12 H 22 O 11 ] (M) 0.3160.2740.2380.1900.146

18. Graphing 500 Is the following reaction first or second order? Second Order

19. Mechanisms 100 The decomposition of hydrogen peroxide is catalyzed by iodide ion. The catalyzed reaction is thought to proceed by a two- step mechanism: H 2 O 2 + I -  H 2 O + IO - (slow) IO - + H 2 O 2  H 2 O + O 2 + I - (fast) Write the chemical equation for the overall process. 2H 2 O 2  2H 2 O + O 2

20. Mechanisms 200 The decomposition of hydrogen peroxide is catalyzed by iodide ion. The catalyzed reaction is thought to proceed by a two- step mechanism: H 2 O 2 + I -  H 2 O + IO - (slow) IO - + H 2 O 2  H 2 O + O 2 + I - (fast) Predict the rate law for the overall process. Rate = k[H 2 O 2 ]

21. Mechanisms 300 You find the reaction 4HBr + O 2  2H 2 O + 2Br 2 to be first order with respect to HBr and first order with respect to O 2. You propose the following mechanism: HBr + O 2  HOOBr HOOBr + HBr  2HOBr HOBr + HBr  H 2 O + Br 2 Based of the rate law which step is rate determining? Rate = k[HBr][O 2 ] The first step is rate determining.

22. Mechanisms 400 The following mechanism has been proposed for the reaction of NO with H 2 to form N 2 O and H 2 O: NO + NO  N 2 O 2 N 2 O 2 +H 2  N 2 O + H 2 O The observed rate law is rate = k[NO] 2 [H 2 ]. What can we conclude about the relative speeds of the first and second reactions? The second step is slow (rate determining) and the first step is fast.

23. Mechanisms 500 Ozone in the upper atmosphere can be destroyed by the following two-step mechanism: Cl + O 3  ClO + O 2 ClO + O  Cl + O 2 What is the overall reaction and list any catalysts or intermediates? O 3 + O  2O 2 Catalyst – Cl Intermediate - ClO

24. Activation Energy 100 What is the activation energy? The difference in energy between the energy to the transition state and the energy of the reactants.

25. Activation Energy 200 The rate of the reaction CH 3 COOC 2 H 5 + OH -  CH 3 COO - + C 2 H 5 OH Was measured at several temperatures, and the following data was collected: Temperature ( o C) k(M -1 s -1 ) Temperature ( o C) k(M -1 s -1 ) 15 0.0521 25 0.101 35 0.184 45 0.332 Determine this data, determine E a. 47,041.61 J/mol

26. Activation Energy 300 The temperature dependence of the rate constant for the reaction is tabulated as follows: Temperature (K)k (M -1 s -1 ) Temperature (K)k (M -1 s -1 ) 600 0.028 650 0.22 700 1.3 750 6.0 800 23 Calculate E a. 133,803.44 J/mol

27. Activation Energy 400 What part of the energy profile of a reaction is affected by a catalyst? Activation energy

28. Activation Energy 500 The oxidation of SO 2 to SO 3 is catalyzed by NO 2. The reaction proceeds as follows: NO 2 + SO 2  NO + SO 3 2NO + O 2  2NO 2 Why do we consider NO 2 a catalyst and not an intermediate in this reaction? NO 2 is present at the beginning and end of the reaction. Intermediates are formed during the reaction and used during the reaction.

29. Surprise 100 What are the 4 factors that affect the rate of a reaction? 1.Concentration of reactants 2. Catalysts 3. State of reactants 4. Temperature

30. Surprise 200 The decomposition of N 2 O 5 in carbon tetrachloride proceeds as follows: 2N 2 O 5  4NO 2 + O 2. The rate law is first order in N 2 O 5. At 64 o C the rate constant is 4.82 x 10 -3 s -1. What happens to the rate when the concentration of N 2 O 5 is doubled? The rate doubles.

31. Surprise 300 Consider the hypothetical reaction between A, B, and C that is first order in A, zero order in B, and second order in C. How does the rate change when [A] is doubled and the other reactant concentrations are held constant? The rate doubles.

32. Surprise 400 Consider the hypothetical reaction between A, B, and C that is first order in A, zero order in B, and second order in C. How does the rate change when [B] is tripled and the other reactant concentrations are held constant? The rate remains the same.

33. Surprise 500 Consider the hypothetical reaction between A, B, and C that is first order in A, zero order in B, and second order in C. By what factor does the rate change when the concentrations of all three reactants are tripled? The rate increases 27 fold.