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The active ingredient in an over the counter pain killer analgesic decomposes with a rate constant, k = 9.05 × 104 day1. How many days does it take for 15% of the original ingredient to decompose?


A) 730 days
B) 414 days
C) 365 days
D) 180 days
E) 78 days

F) A) and B)
G) A) and D)

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The rate law for the reaction 3A → 2B is rate = k[A] with a rate constant of 0.0447 hr1. What is the half-life of the reaction?


A) 0.0224 hr
B) 0.0645 hr
C) 15.5 hr
D) 22.4 hr
E) 44.7 hr

F) All of the above
G) A) and B)

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Sucrose decomposes to fructose and glucose in acid solution. When ln [sucrose] is plotted vs. time, a straight line with slope of −0.208 hr1 results. What is the rate law for the reaction?


A) Rate = 0.208 hr 1 [sucrose] 2
B) Rate = 0.208 hr 1 [sucrose]
C) Rate = 0.0433 hr [sucrose] 2
D) Rate = 0.0433 hr [sucrose]
E) Rate = 0.208 mol L 1hr 1 [sucrose] 0

F) B) and D)
G) A) and B)

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The rate law cannot be predicted from the stoichiometry of a reaction.

A) True
B) False

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The rate constant for the reaction 3A → 4B is 6.00 × 103 L mol1min1. How long will it take the concentration of A to drop from 0.75 M to 0.25 M?


A) 2.2 × 10 3 min
B) 5.5 × 10 3 min
C) 180 min
D) 440 min
E) 5.0 × 10 2 min

F) B) and C)
G) A) and E)

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The greater the energy of activation, Ea, the faster will be the reaction.

A) True
B) False

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For the reaction A(g) + 2B(g) → 2C(g) + 2D(g) The following data were collected at constant temperature. Determine the correct rate law for this reaction. For the reaction A(g)  + 2B(g)  → 2C(g)  + 2D(g)  The following data were collected at constant temperature. Determine the correct rate law for this reaction.   A) Rate = k[A] [B] B) Rate = k[A] <sup>2 </sup>[B] C) Rate = k[A] [B] <sup>2</sup> D) Rate = k[A] E) Rate = k[A] <sup>3</sup>


A) Rate = k[A] [B]
B) Rate = k[A] 2 [B]
C) Rate = k[A] [B] 2
D) Rate = k[A]
E) Rate = k[A] 3

F) A) and B)
G) A) and C)

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A catalyst lowers the activation energy but does not affect the mechanism of a reaction.

A) True
B) False

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The decomposition of SOCl2 is first-order in SOCl2. If the half-life for the reaction is 4.1 hr, how long would it take for the concentration of SOCl2 to drop from 0.36 M to 0.045 M?


A) 0.52 hr
B) 1.4 hr
C) 12 hr
D) 33 hr
E) > 40 hr

F) B) and C)
G) C) and E)

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An elementary reaction is a simple, one-step process.

A) True
B) False

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Which one of the following sets of units is appropriate for a third-order rate constant?


A) s 1
B) mol L 1s 1
C) L mol 1s 1
D) L 2 mol 2s 1
E) L 3 mol 3s 1

F) A) and B)
G) A) and C)

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A reaction is first-order with respect to the reactant R. Which of the following plots will produce a straight line?


A) [R] vs. 1/time
B) 1/[R] vs. time
C) [R] 2 vs. time
D) 1/[R] 2 vs. time
E) ln[R] vs. time

F) A) and B)
G) C) and E)

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A reaction has an activation energy of 195.0 kJ/mol. When the temperature is increased from 200°C to 220°C, the rate constant will increase by a factor of


A) 1.1.
B) 4.3 × 10 4.
C) 3.2.
D) 7.5.
E) None of these choices are correct.

F) All of the above
G) B) and E)

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Carbon-14 is a radioactive isotope which decays with a half-life of 5730 years. What is the first-order rate constant for its decay, in units of years1?


A) 5.25 × 10 5 years 1
B) 1.21 × 10 4 years 1
C) 1.75 × 10 4 years 1
D) 3.49 × 10 4 years 1
E) 3.97 × 10 3 years 1

F) A) and B)
G) All of the above

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A study of the decomposition reaction 3RS2 → 3R + 6S yields the following initial rate data. A study of the decomposition reaction 3RS<sub>2 </sub>→ 3R + 6S yields the following initial rate data.   What is the rate constant for the reaction? A) 0.0103 L mol <sup>−</sup><sup>1</sup>s <sup>−</sup><sup>1</sup> B) 0.263 L mol <sup>−</sup><sup>1</sup>s <sup>−</sup><sup>1</sup> C) 0.571 L mol <sup>−</sup><sup>1</sup>s <sup>−</sup><sup>1</sup> D) 1.17 L mol <sup>−</sup><sup>1</sup>s <sup>−</sup><sup>1</sup> E) 1.75 L mol <sup>−</sup><sup>1</sup>s <sup>−</sup><sup>1</sup> What is the rate constant for the reaction?


A) 0.0103 L mol 1s 1
B) 0.263 L mol 1s 1
C) 0.571 L mol 1s 1
D) 1.17 L mol 1s 1
E) 1.75 L mol 1s 1

F) A) and E)
G) D) and E)

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In the lock and key model of enzyme action, the active site on the enzyme provides an exact fit for the substrate.

A) True
B) False

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A reactant R is being consumed in a first-order reaction. What fraction of the initial R is consumed in 4.0 half-lives?


A) 0.94
B) 0.87
C) 0.75
D) 0.13
E) 0.063

F) B) and C)
G) None of the above

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Consider the following mechanism for the oxidation of bromide ions by hydrogen peroxide in aqueous acid solution. H+ + H2O2 ⇄ H2O+−OH (rapid equilibrium) H2O+−OH + Br → HOBr + H2O (slow) HOBr + H+ + Br → Br2 + H2O (fast) Which of the following rate laws is consistent with the mechanism?


A) Rate = k[H 2O 2][H +] 2[Br ]
B) Rate = k[H 2O +−OH][Br ]
C) Rate = k[H 2O 2][H +][Br ]
D) Rate = k[HOBr][H +][Br ][H 2O 2]
E) Rate = k[Br ]

F) B) and C)
G) A) and C)

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