Question 1

A city's water supply is contaminated with a toxin at a concentration of 0.63 mg/L. Fortunately, this toxin decomposes to a safe mixture of products by first-order kinetics with a rate constant of 0.27 day-1. How long will it take for half of the toxin to decompose

Accepted Answer

A)   0.17 days
B)   0.27 days
C)   0.38 days
D)   2.3 days
E)   2.6 daysF) B) and E)
G) B) and D)

Question 2

Concerning the rate law, Rate = k[A]2[B], what are appropriate units for the rate constant k

Accepted Answer

A)   s-1
B)   M-1s-1
C)   M-2s-1
D)   M/s
E)   M2/sF) A) and B)
G) A) and C)

Question 3

Chlorine dioxide reacts in basic water to form chlorite and chlorate according to the following chemical equation: 2ClO2(aq)  + 2OH-(aq)   →arr→  ClO2-(aq)  + ClO3-(aq)  + H2O(l) 
A kinetic study of this reaction under a certain set of conditions yielded the data below.  Exp⁡[ClO2](M) [OH−](M) −Δ[ClO2]/Δt(M/s) 10.05000.1005.75×10−220.1000.1002.30×10−130.1000.05001.15×10−1\begin{array}{|l|c|c|c|}\hline \operatorname{Exp} & {\left[\mathrm{ClO}_{2}ight](\mathrm{M}) } & {\left[\mathrm{OH}^{-}ight](\mathrm{M}) } & -\Delta\left[\mathrm{ClO}_{2}ight] / \Delta \mathrm{t}(\mathrm{M} / \mathrm{s})  \\hline 1 & 0.0500 & 0.100 & 5.75 	imes 10^{-2} \\hline 2 & 0.100 & 0.100 & 2.30 	imes 10^{-1} \\hline 3 & 0.100 & 0.0500 & 1.15 	imes 10^{-1} \\hline\end{array}Exp123​[ClO2​](M) 0.05000.1000.100​[OH−](M) 0.1000.1000.0500​−Δ[ClO2​]/Δt(M/s) 5.75×10−22.30×10−11.15×10−1​​  Which one of the following is the rate law for this reaction

Accepted Answer

A)   rate = k[ClO2][OH-]
B)   rate = k[ClO2]2[OH-]
C)   rate = k[ClO2][OH-]2
D)   rate = k[ClO2]2[OH-]2
E)   rate = k[ClO2]4[OH-] F) C) and E)
G) A) and C)

Question 4

The rate constant for a certain first-order reaction is 0.40/min. What is the initial rate in mole/L·min, if the initial concentration of the compound involved is 0.50 mol/L

Accepted Answer

A)   0.20
B)   0.40
C)   0.60
D)   0.80
E)   None of the aboveF) All of the above
G) C) and D)

Question 5

When acetaldehyde at a pressure of 364 mmHg is introduced into an evacuated 500. mL flask at 518 ∘\circ∘ C, the half-life for the second-order decomposition process, CH3CHO  →\rarr→ CH4 + CO, is 410. s. What will the total pressure in the flask be after 1.00 hour

Accepted Answer

A)   327 mmHg
B)   654 mmHg
C)   37 mmHg
D)   691 mmHg
E)   728 mmHg F) B) and C)
G) D) and E)

Question 6

The following mechanism has been suggested for the reaction:  H2O2+2H++2I−→I2+2H2OH2O2+I−→HOI+OH−SlowOH−+H+→H2OFastHOI+H++I−→I2+H2OFast\begin{array}{ll}\mathrm{H}_{2} \mathrm{O}_{2}+2 \mathrm{H}^{+}+2 \mathrm{I}^{-} ightarrow \mathrm{I}_{2}+2 \mathrm{H}_{2} \mathrm{O} \\mathrm{H}_{2} \mathrm{O}_{2}+\mathrm{I}^{-} ightarrow \mathrm{HOI}+\mathrm{OH}^{-} & \mathrm{Slow}\\mathrm{OH}^{-}+\mathrm{H}^{+} ightarrow \mathrm{H}_{2} \mathrm{O} & \mathrm{Fast}\\mathrm{HOI}+\mathrm{H}^{+}+\mathrm{I}^{-} ightarrow \mathrm{I}_{2}+\mathrm{H}_{2} \mathrm{O}& \mathrm{Fast}\end{array}H2​O2​+2H++2I−→I2​+2H2​OH2​O2​+I−→HOI+OH−OH−+H+→H2​OHOI+H++I−→I2​+H2​O​SlowFastFast​  Identify the rate law that is consistent with this mechanism.

Accepted Answer

A)   Rate = k[H2O2][I-]
B)   Rate = k[HOI][OH-]
C)   Rate = k[OH-][H+]
D)   Rate = k[HOI][H+][I-]
E)   Rate = k[H2O2][[I-]2[H+]2 F) C) and E)
G) A) and B)

Question 7

The rate constant of a first-order reaction, A $\rarr$ products, can be determined from a graph of ln[A] versus t.

Accepted Answer

A) True 
 B)False

Question 8

Concerning the decomposition of A, A  →\rarr→   products, which of the following methods could be used to determine the order of the reaction with respect to A
I. Plot [A] vs time, ln[A] vs time, and 1/[A] vs time and identify which plot yields a straight line.
II. Vary the concentration of A and note by what factor the rate changes.
III. Identify if successive half lives of A double, halve, or stay constant.

Accepted Answer

A)   I only
B)   II only
C)   III only
D)   I and III
E)   I, II, and III F) All of the above
G) A) and D)

Question 9

At 30 ∘\circ∘ C, by how much is a reaction's activation energy decreased by the addition of a catalyst if the catalyst triples the reaction rate

Accepted Answer

A)   2.77 kJ/mol
B)   274 J/mol
C)   2.70 J/mol
D)   119 J/mol
E)   1.20 kJ/mol F) A) and E)
G) C) and D)

Question 10

Hydrogen peroxide decomposes to water and oxygen gas, and the activation energy for this process is 42 kJ/mol. The hydrogen peroxide formed in biological processes is harmful to tissue, but the enzyme catalase catalyzes the decomposition of hydrogen peroxide by lowering the activation energy to 7.0 kJ/mol. Assuming the frequency factor is the same for both processes and independent of temperature, calculate the temperature required for the uncatalyzed decomposition to proceed at the same rate as the enzyme-catalyzed decomposition at 37 ∘\circ∘ C (normal human body temperature) .

Accepted Answer

A)   1200 ∘\circ∘ C
B)   1400 ∘\circ∘ C
C)   1600 ∘\circ∘ C
D)   1800 ∘\circ∘ C
E)   None of the above F) A) and B)
G) B) and E)

Question 11

Nitrogen pentoxide decomposes by a first-order process yielding N2O4 and oxygen.2N2O5  →\rarr→ 2N2O4 + O2 At a given temperature, the half-life of N2O5 is 0.90 hr. What is the first-order rate constant for N2O5 decomposition

Accepted Answer

A)   0.17 hr-1
B)   0.37 hr-1
C)   0.57 hr-1
D)   0.77 hr-1
E)   None of the above F) C) and D)
G) B) and D)

Question 12

The rate law for the reaction 2NO2 + O3  →\rarr→ N2O5 + O2 is rate = k[NO2][O3]. Which one of the following mechanisms is consistent with this rate law

Accepted Answer

A)   NO2 + NO2  →\rarr→  N2O4 (fast)  N2O4 + O3  →\rarr→ N2O5 + O2 (slow) 
B)   NO2 + O3  →\rarr→  NO5 (fast)  NO5 + NO5  →\rarr→ N2O5 + 5/2O2 (slow) 
C)   NO2 + O3  →\rarr→  NO3 + O2 (slow)  NO3 + NO2  →\rarr→ N2O5 (fast) 
D)   NO2 + NO2  →\rarr→ N2O2 + O2 (slow)  E) None of the above
F) A) and D)

Question 13

For the reaction whose rate law is rate = k[X], a plot of which of the following is a straight line

Accepted Answer

A)   [X] versus time
B)   ln [X] versus time
C)   1/[X] versus time
D)   [X] versus 1/time
E)   ln [X] versus 1/timeF) A) and B)
G) None of the above

Question 14

Given that Ea for a certain biological reaction is 48 kJ/mol and that the rate constant is 2.5 *10-2 s-1 at 15 ∘\circ∘ C, what is the rate constant at 37 ∘\circ∘ C

Accepted Answer

A)   2.7 * 10-2 s-1
B)   2.5 * 10-1 s-1
C)   1.0 * 10-1 s-1
D)   6.0 * 10-3 s-1
E)   1.1 s-1 F) None of the above
G) B) and C)

Question 15

Use the following data to determine the rate law for the reaction shown below.2NO + H2  →arr→  N2O + H2O  Expt.#[NO]0[H2]0Initial rate10.0210.0651.46M/min20.0210.2601.46M/min30.0420.0655.84M/min\begin{array}{lccc} Expt.\# &[\mathrm{NO}]_{0}&\left[\mathrm{H}_{2}ight]_{0}&Initial~ rate \\hline1 & 0.021 & 0.065 & 1.46 \mathrm{M} / \mathrm{min} \2 & 0.021 & 0.260 & 1.46 \mathrm{M} / \mathrm{min} \3 & 0.042 & 0.065 & 5.84 \mathrm{M} / \mathrm{min}\end{array}Expt.#123​[NO]0​0.0210.0210.042​[H2​]0​0.0650.2600.065​Initial rate1.46M/min1.46M/min5.84M/min​​

Accepted Answer

A)   rate = k[NO]
B)   rate = k[NO]2
C)   rate = k[NO][H2]
D)   rate = k[NO]2[H2]
E)   rate = k[NO]2[H2]2 F) B) and D)
G) A) and E)

Question 16

The isomerization of methyl isocyanide, CH3NC  →\rarr→  CH3CN, follows first-order kinetics. The half-lives were found to be 161 min at 199 ∘\circ∘ C and 12.5 min at 230 ∘\circ∘ C. Calculate the activation energy for this reaction.

Accepted Answer

A)   6.17 * 10-3 kJ/mol
B)   31.4 kJ/mol
C)   78.2 kJ/mol
D)   124 kJ/mol
E)   163 kJ/mol F) A) and D)
G) None of the above

Question 17

The thermal decomposition of acetaldehyde, CH3CHO  →arr→   CH4 + CO, is a second-order reaction. The following data were obtained at 518 ∘\circ∘ C.   Time, s Pressure CH3CHO,mmHg036442330105290720132\begin{array}{cc}	ext { Time, } \mathrm{s} & 	ext { Pressure } \mathrm{CH}_{3} \mathrm{CHO}, \mathrm{mmHg} \\hline0 & 364 \42 & 330 \105 & 290 \720 & 132\end{array} Time, s042105720​ Pressure CH3​CHO,mmHg364330290132​​  Based on the data given, what is the half-life for the disappearance of acetaldehyde

Accepted Answer

A)   1.5 * 105 s
B)   410 s
C)   5.4 * 107 s
D)   520 s
E)   305 s F) D) and E)
G) C) and D)

Question 18

The rate law predicted by the following two-step mechanism is rate = k[A][B]. $\begin{array}{lr}
\mathrm{A} \rightarrow \mathrm{C}+\mathrm{B} & \text { slow } \
\mathrm{A}+\mathrm{B} \rightarrow \mathrm{C}+\mathrm{E} & \text { fast }
\end{array}$

Accepted Answer

A) True 
 B)False

Question 19

For the reaction X2 + Y + Z  →\rarr→  XY + XZ, it is found that the rate equation is rate = k [X2][Y]. Why does the concentration of Z have no effect on the rate

Accepted Answer

A)   The concentration of Z is very small and the others are very large.
B)   Z must react in a step after the rate determining step.
C)   Z is an intermediate.
D)   The fraction of molecules of Z that have very high energies is zero.
E)   The activation energy for Z to react is very high. F) All of the above
G) A) and B)

Question 20

The following reaction in aqueous solution was found to be first order in [OH-], first order in [C2H5Br], and inverse first order in Br-.C2H5Br + OH-  →\rarr→  C2H5OH + Br- Which one of the following mechanisms is consistent with the observed reaction order

Accepted Answer

A)   C2H5Br  →\rarr→ C2H5+ + Br- fast C2H5+ + OH-  →\rarr→ C2H5OH slow
B)   C2H5Br +H2O  →\rarr→ C2H5OH + H+ + Br- slowH+ + OH-   →\rarr→  H2O fast
C)   C2H5Br  →\rarr→  C2H5+ + Br- slow C2H5+ + OH-  →\rarr→ C2H5OH fast
D)   C2H5Br  →\rarr→  C2H5+ + Br- slow E) B) and C)
F) A) and D)

Exam 13: Chemical Kinetics

The following reaction in aqueous solution was found to be first order in [OH^-], first order in [C₂H₅Br], and inverse first order in Br^-.C₂H₅Br + OH^- $\rarr$ C₂H₅OH + Br^- Which one of the following mechanisms is consistent with the observed reaction order

Correct Answer
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Concerning the rate law, Rate = k[A]²[B], what are appropriate units for the rate constant k

Correct Answer
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The rate constant of a first-order reaction, A $\rarr$ products, can be determined from a graph of ln[A] versus t.

Correct Answer
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A city's water supply is contaminated with a toxin at a concentration of 0.63 mg/L. Fortunately, this toxin decomposes to a safe mixture of products by first-order kinetics with a rate constant of 0.27 day^-1. How long will it take for half of the toxin to decompose

Correct Answer
verified

The rate law for the reaction 2NO₂ + O₃ $\rarr$ N₂O₅ + O₂ is rate = k[NO₂][O₃]. Which one of the following mechanisms is consistent with this rate law

Correct Answer
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The isomerization of methyl isocyanide, CH₃NC $\rarr$ CH₃CN, follows first-order kinetics. The half-lives were found to be 161 min at 199^$\circ$C and 12.5 min at 230^$\circ$C. Calculate the activation energy for this reaction.

Correct Answer
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When acetaldehyde at a pressure of 364 mmHg is introduced into an evacuated 500. mL flask at 518^$\circ$C, the half-life for the second-order decomposition process, CH₃CHO $\rarr$ CH₄ + CO, is 410. s. What will the total pressure in the flask be after 1.00 hour

Correct Answer
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For the reaction X₂ + Y + Z $\rarr$ XY + XZ, it is found that the rate equation is rate = k [X₂][Y]. Why does the concentration of Z have no effect on the rate

Correct Answer
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Correct Answer
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Given that E_a for a certain biological reaction is 48 kJ/mol and that the rate constant is 2.5 *10^-2 s^-1 at 15^$\circ$C, what is the rate constant at 37^$\circ$C

Correct Answer
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At 30^$\circ$C, by how much is a reaction's activation energy decreased by the addition of a catalyst if the catalyst triples the reaction rate

Correct Answer
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Correct Answer
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The rate law predicted by the following two-step mechanism is rate = k[A][B]. $\begin{array}{lr}\mathrm{A} \rightarrow \mathrm{C}+\mathrm{B} & \text { slow } \\\mathrm{A}+\mathrm{B} \rightarrow \mathrm{C}+\mathrm{E} & \text { fast }\end{array}$

Correct Answer
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For the reaction whose rate law is rate = k[X], a plot of which of the following is a straight line

Correct Answer
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Correct Answer
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Correct Answer
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The rate constant for a certain first-order reaction is 0.40/min. What is the initial rate in mole/L·min, if the initial concentration of the compound involved is 0.50 mol/L

Correct Answer
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Nitrogen pentoxide decomposes by a first-order process yielding N₂O₄ and oxygen.2N₂O₅ $\rarr$ 2N₂O₄ + O₂ At a given temperature, the half-life of N₂O₅ is 0.90 hr. What is the first-order rate constant for N₂O₅ decomposition

Correct Answer
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Correct Answer
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Correct Answer
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Exam 13: Chemical Kinetics

The following reaction in aqueous solution was found to be first order in [OH-], first order in [C2H5Br], and inverse first order in Br-.C2H5Br + OH- →\rarr→ C2H5OH + Br- Which one of the following mechanisms is consistent with the observed reaction order

Correct AnswerverifiedShow Answer

Concerning the rate law, Rate = k[A]2[B], what are appropriate units for the rate constant k

Correct AnswerverifiedShow Answer

The rate constant of a first-order reaction, A →\rarr→ products, can be determined from a graph of ln[A] versus t.

Correct AnswerverifiedShow Answer

A city's water supply is contaminated with a toxin at a concentration of 0.63 mg/L. Fortunately, this toxin decomposes to a safe mixture of products by first-order kinetics with a rate constant of 0.27 day-1. How long will it take for half of the toxin to decompose

Correct AnswerverifiedShow Answer

The rate law for the reaction 2NO2 + O3 →\rarr→ N2O5 + O2 is rate = k[NO2][O3]. Which one of the following mechanisms is consistent with this rate law

Correct AnswerverifiedShow Answer

The isomerization of methyl isocyanide, CH3NC →\rarr→ CH3CN, follows first-order kinetics. The half-lives were found to be 161 min at 199 ∘\circ∘ C and 12.5 min at 230 ∘\circ∘ C. Calculate the activation energy for this reaction.

Correct AnswerverifiedShow Answer

When acetaldehyde at a pressure of 364 mmHg is introduced into an evacuated 500. mL flask at 518 ∘\circ∘ C, the half-life for the second-order decomposition process, CH3CHO →\rarr→ CH4 + CO, is 410. s. What will the total pressure in the flask be after 1.00 hour

Correct AnswerverifiedShow Answer

For the reaction X2 + Y + Z →\rarr→ XY + XZ, it is found that the rate equation is rate = k [X2][Y]. Why does the concentration of Z have no effect on the rate

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Given that Ea for a certain biological reaction is 48 kJ/mol and that the rate constant is 2.5 *10-2 s-1 at 15 ∘\circ∘ C, what is the rate constant at 37 ∘\circ∘ C

Correct AnswerverifiedShow Answer

At 30 ∘\circ∘ C, by how much is a reaction's activation energy decreased by the addition of a catalyst if the catalyst triples the reaction rate

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

For the reaction whose rate law is rate = k[X], a plot of which of the following is a straight line

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

The rate constant for a certain first-order reaction is 0.40/min. What is the initial rate in mole/L·min, if the initial concentration of the compound involved is 0.50 mol/L

Correct AnswerverifiedShow Answer

Nitrogen pentoxide decomposes by a first-order process yielding N2O4 and oxygen.2N2O5 →\rarr→ 2N2O4 + O2 At a given temperature, the half-life of N2O5 is 0.90 hr. What is the first-order rate constant for N2O5 decomposition

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

The following reaction in aqueous solution was found to be first order in [OH^-], first order in [C₂H₅Br], and inverse first order in Br^-.C₂H₅Br + OH^- $\rarr$ C₂H₅OH + Br^- Which one of the following mechanisms is consistent with the observed reaction order

Correct Answer
verified

Concerning the rate law, Rate = k[A]²[B], what are appropriate units for the rate constant k

Correct Answer
verified

The rate constant of a first-order reaction, A $\rarr$ products, can be determined from a graph of ln[A] versus t.

Correct Answer
verified

A city's water supply is contaminated with a toxin at a concentration of 0.63 mg/L. Fortunately, this toxin decomposes to a safe mixture of products by first-order kinetics with a rate constant of 0.27 day^-1. How long will it take for half of the toxin to decompose

Correct Answer
verified

The rate law for the reaction 2NO₂ + O₃ $\rarr$ N₂O₅ + O₂ is rate = k[NO₂][O₃]. Which one of the following mechanisms is consistent with this rate law

Correct Answer
verified

The isomerization of methyl isocyanide, CH₃NC $\rarr$ CH₃CN, follows first-order kinetics. The half-lives were found to be 161 min at 199^$\circ$C and 12.5 min at 230^$\circ$C. Calculate the activation energy for this reaction.

Correct Answer
verified

When acetaldehyde at a pressure of 364 mmHg is introduced into an evacuated 500. mL flask at 518^$\circ$C, the half-life for the second-order decomposition process, CH₃CHO $\rarr$ CH₄ + CO, is 410. s. What will the total pressure in the flask be after 1.00 hour

Correct Answer
verified

For the reaction X₂ + Y + Z $\rarr$ XY + XZ, it is found that the rate equation is rate = k [X₂][Y]. Why does the concentration of Z have no effect on the rate

Correct Answer
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Correct Answer
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Given that E_a for a certain biological reaction is 48 kJ/mol and that the rate constant is 2.5 *10^-2 s^-1 at 15^$\circ$C, what is the rate constant at 37^$\circ$C

Correct Answer
verified

At 30^$\circ$C, by how much is a reaction's activation energy decreased by the addition of a catalyst if the catalyst triples the reaction rate

Correct Answer
verified

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Nitrogen pentoxide decomposes by a first-order process yielding N₂O₄ and oxygen.2N₂O₅ $\rarr$ 2N₂O₄ + O₂ At a given temperature, the half-life of N₂O₅ is 0.90 hr. What is the first-order rate constant for N₂O₅ decomposition

Correct Answer
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Correct Answer
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Correct Answer
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