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Chemistry Raymond Chang 10 th edition Chapter 13 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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Presentation on theme: "Chemistry Raymond Chang 10 th edition Chapter 13 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display."— Presentation transcript:

1 Chemistry Raymond Chang 10 th edition Chapter 13 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2 Question 1 For the reaction 2A + B → C it is found that changing the concentration of A has no impact on the rate, but when B is doubled the rate doubles. The rate law is A) rate = k[A] 2 [B]. B) rate = k[A][B] 2. C) rate = k[B] 2. D) none of the above.

3 Question 2 If the activation energy of a reaction is decreased, the reaction rate will increase. A) True B) False

4 Question 3 Which of the following is true? A) A catalyst is not consumed in the reaction. B) A catalyst speeds up the forward reaction. C) A catalyst speeds up the reverse reaction. D) A catalyst decreases the activation energy. E) All of the above.

5 Question 4 If a reaction is first order in one reactant and first order in the only other reactant, the units of the rate constant would be A) Ms -1. B) M -1 s. C) Ms. D) M -1 s -1. E) none of the above

6 Question 5 Which of the following will cause the reaction rate to increase? A) Increasing the temperature. B) Adding a catalyst. C) Reducing the concentration of reactants. D) Both A and B. E) Both B and C.

7 Question 6 Using the data below, determine the rate law for the reaction of A with B to produce C. Exp 1: M A, M B, rate M/s Exp 2: M A, M B, rate M/s Exp 3: M A, M B, rate M/s A) rate=k[A] 2 [B] B) rate=k[A] 2 C) rate=k[B] 2 D) rate=k[A][B]

8 Question 7 If a proposed mechanism is inconsistent with the experimentally determined rate law, then the rate law must be inaccurate. A) True B) False

9 Question 8 If a proposed mechanism is consistent with the experimentally determined rate law, then the mechanism must be correct. A) True B) False

10 Question 9 If a reaction is exothermic, then the activation energy for the forward reaction is __________ the activation energy for the reverse reaction. A) greater than B) less than C) equal to D) none of the above--there is no relationship between the values

11 Question 10 Reactions rarely occur by mechanisms that include trimolecular elementary steps because A) the simultaneous collision of three molecules has a low probability. B) simpler reaction mechanisms can always support the same rate law. C) the math involved is too complicated. D) all of the above.

12 Question 11 Which of the following can be used to determine the rate of a chemical reaction? A) Measuring a change in color B) Measuring a change in mass C) Measuring a change in concentration of a certain species D) All of the above E) None of the above

13 Question 12 The average rate of a reaction is the rate of reaction at any given time. A) True B) False

14 Question 13 The rate of a reaction A) is always dependent of the concentration of the reactants. B) may or may not depend on reactant concentration. C) is never constant throughout a reaction. D) can be calculated for first order and second order reactions only.

15 Question 14 For a first order reaction, a plot of the rate constant versus time should be A) an exponential curve. B) a straight line going through the origin. C) a straight line parallel to the x axis. D) a straight line parallel to the y axis. E) none of the above.

16 Question 15 In the reaction N 2 + 3H 2 → 2NH 3, the rate of formation of ammonia at a given moment is mol/s. What is the rate of reaction of hydrogen gas at the same moment? A) mol/s B) mol/s C) mol/s D) mol/s E) mol/s

17 Question 16 The reaction C 2 H 6 → 2CH 3 · is first order with k = 2.50x10 -3 s -1. How much time will be necessary for the concentration of C 2 H 6 to decrease to 20 % of the initial amount? A) 644 s B) 280. s C) s D) s E) None of the above

18 Question 17 The reaction C 2 H 6 → 2CH 3 · is first order with k = 2.5x10 -3 s -1. Which of the following changes in concentration will last longer than the others? A) 2.0 M → 1.0 M B) 1.0 M → 0.50 M C) 0.50 M → 0.25 M D) 0.80 M → 0.40 M E) None of the above

19 Question 18 Which type of plot will be linear for a second order reaction? A) [A] vs time B) ln[A] vs time C) 1/[A] vs time D) [A] 2 vs time E) None is linear

20 Question 19 How does a catalyst work? A) It increases the rate of reaction proportionally with its concentration B) It decreases the half time of the reaction C) It decreases the activation energy of the reaction D) It slows down the reverse reaction E) None of the above

21 Question 20 A unimolecular reaction follows first order kinetics, and a bimolecular reaction follows second order kinetics. A) True B) False

22 Answer Key – Chapter D 2. A 3. E 4. D 5. D 6. B 7. B 8. B 9. B 10. A 11. D 12. B 13. B 14. C 15. C 16. A 17. A 18. C 19. C 20. B


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