Question 1

What is the half-life of a first-order reaction if the rate constant is 6.2 × 10-3 s-1?

Accepted Answer

A)  8.9 × 10-3 s 
B)  0.097 s 
C)  5.77 s 
D)  1.1 × 102 s 
E)  1.6 × 102 s 
A)  8.9 × 10-3 s 
B)  0.097 s 
C)  5.77 s 
D)  1.1 × 102 s 
E)  1.6 × 102 s D

Question 2

For the first-order reaction below,the initial concentration of A is 0.240 M.If the concentration of A decreases to 0.0800 M after 21.8 hours,what is the half-life of the reaction? $ \mathrm{A} \rightarrow \mathrm{B} $$ \quad$$ \quad$$ \quad$$ \quad$$ \quad$rate $ =k[\mathrm{~A}] $

Accepted Answer

A)  0.0504 hrs 
B)  1.28 hrs 
C)  7.26 hrs 
D)  10.4 hrs 
E)  13.8 hrs 
A)  0.0504 hrs 
B)  1.28 hrs 
C)  7.26 hrs 
D)  10.4 hrs 
E)  13.8 hrs E

Question 3

The rate constant for the decomposition of cyclobutane is 2.08 × 10−2 s−1 at high temperatures. C4H8(g)→ 2C2H4(g)
How many seconds are required for an initial concentration of 0.100 M C4H8(g)to decrease to 0.0450 M?

Accepted Answer

A)  0.00114 s 
B)  1.07 s 
C)  2.64 s 
D)  38.4 s 
E)  874 s 
A)  0.00114 s 
B)  1.07 s 
C)  2.64 s 
D)  38.4 s 
E)  874 s D

Question 4

Which equation is used to calculate the half-life of the second-order equation below? $2 \mathrm{~A} \rightarrow \mathrm{B} \quad\quad\quad\quad\quad\quad\quad \text { rate }=k[\mathrm{~A}]^{2}$

Accepted Answer

A)  $t_{1 / 2}=\frac{1}{k[A]_{0}}$ 
B)  $t_{1 / 2}=\frac{\ln (2)}{k[A]_{0}}$ 
C)  $t_{1 / 2}=\frac{\ln (2)}{k}$ 
D)  $t_{1 / 2}=\frac{\ln (2)}{[A]_{0}}$ 
E)  $t_{1 / 2}=\frac{k}{2[A]_{0}}$ 
A)  $t_{1 / 2}=\frac{1}{k[A]_{0}}$ 
B)  $t_{1 / 2}=\frac{\ln (2)}{k[A]_{0}}$ 
C)  $t_{1 / 2}=\frac{\ln (2)}{k}$ 
D)  $t_{1 / 2}=\frac{\ln (2)}{[A]_{0}}$ 
E)  $t_{1 / 2}=\frac{k}{2[A]_{0}}$

Question 5

For the second-order reaction below,the rate constant of the reaction is 9.4 × 10-3 M-1s-1.How much time (in seconds)is required to decrease the concentration of A from 2.16 M to 0.40 M? $2 \mathrm{~A} \rightarrow \mathrm{B} \quad\quad\quad\quad\quad \text { rate }=k[\mathrm{~A}]^{2}$

Accepted Answer

A)  2.0 × 101 s 
B)  7.8 × 101 s 
C)  1.8 × 102 s 
D)  1.9 × 102 s 
E)  2.2 × 102 s 
A)  2.0 × 101 s 
B)  7.8 × 101 s 
C)  1.8 × 102 s 
D)  1.9 × 102 s 
E)  2.2 × 102 s

Question 6

At a high temperature,the first-order decomposition of N2O5(g)produces NO2(g)and O2(g).If the initial concentration of 0.400 M N2O5(g)is reduced to 0.169 M after 118 seconds,what is the rate constant for the reaction?

Accepted Answer

A)  1.96 × 10−3 s−1 
B)  2.29 × 10−3 s−1 
C)  4.37 × 10−3 s−1 
D)  7.30 × 10−3 s−1 
E)  1.37 × 102 s−1 
A)  1.96 × 10−3 s−1 
B)  2.29 × 10−3 s−1 
C)  4.37 × 10−3 s−1 
D)  7.30 × 10−3 s−1 
E)  1.37 × 102 s−1

Question 7

The correct form of the Arrhenius equation is

Accepted Answer

A)  Ea = Ae?k/RT 
B)  $k=A e^{-E_{a} / R T}$ 
C)  $k=A e^{-R T / E_{a}}$ 
D)  Ea = Aek/RT 
E)  A = Eae?k/RT 
A)  Ea = Ae?k/RT 
B)  $k=A e^{-E_{a} / R T}$ 
C)  $k=A e^{-R T / E_{a}}$ 
D)  Ea = Aek/RT 
E)  A = Eae?k/RT

Question 8

The decomposition of formic acid follows first-order kinetics. 
HCO2H(g)→ CO2(g)+ H2(g)
The half-life for the reaction at 550°C is 24 seconds.How many seconds does it take for the formic acid concentration to decrease by 87.5%?

Accepted Answer

A)  24 s 
B)  36 s 
C)  48 s 
D)  72 s 
E)  96 s 
A)  24 s 
B)  36 s 
C)  48 s 
D)  72 s 
E)  96 s

Question 9

The rate constant of a first-order decomposition reaction is 0.0147 s-1.If the initial concentration of reactant is 0.178 M,what is the concentration of reactant after 30.0 seconds?

Accepted Answer

A)  8.72 × 105 M 
B)  0.0645 M 
C)  0.115 M 
D)  0.0785 M 
E)  0.643 M 
A)  8.72 × 105 M 
B)  0.0645 M 
C)  0.115 M 
D)  0.0785 M 
E)  0.643 M

Question 10

The rate constant at 373 K for a certain reaction is 8.29 × 10−4 s−1 and the activation energy is 12.0 kJ/mole.What is the value of the constant,A,in the Arrhenius equation?

Accepted Answer

A)  0.00832 s−1 
B)  0.0398 s−1 
C)  0.120 s−1 
D)  0.998 s−1 
E)  25.1 s−1 
A)  0.00832 s−1 
B)  0.0398 s−1 
C)  0.120 s−1 
D)  0.998 s−1 
E)  25.1 s−1

Question 11

For the second-order reaction below,the initial concentration of A is 1.00 M.If the concentration of A is reduced to 0.43 M after 75 seconds,what is the rate constant? $2 \mathrm{~A} \rightarrow \mathrm{B} \quad\quad\quad\quad\quad \text { rate }=k[\mathrm{~A}]^{2}$

Accepted Answer

A)  5.2 × 10?4 L/mol?s 
B)  5.7 × 10?3 L/mol?s 
C)  7.6 × 10?3 L/mol?s 
D)  1.1 × 10?2 L/mol?s 
E)  1.8 × 10?2 L/mol?s 
A)  5.2 × 10?4 L/mol?s 
B)  5.7 × 10?3 L/mol?s 
C)  7.6 × 10?3 L/mol?s 
D)  1.1 × 10?2 L/mol?s 
E)  1.8 × 10?2 L/mol?s

Question 12

What did Henry Eyring develop that changed how scientists study rates of reactions?

Accepted Answer

A)  The catalyst model 
B)  The transition-state model 
C)  The liquid-state model 
D)  The temperature dependence model 
E)  The enzyme model 
A)  The catalyst model 
B)  The transition-state model 
C)  The liquid-state model 
D)  The temperature dependence model 
E)  The enzyme model

Question 13

The reaction A → B follows first-order kinetics with a half-life of 21.7 hours.If the concentration of A is 0.023 M after 48.0 hours,what is the initial concentration of A?

Accepted Answer

A)  0.0050 M 
B)  0.051 M 
C)  0.51 M 
D)  0.11 M 
E)  2.0 × 102 M 
A)  0.0050 M 
B)  0.051 M 
C)  0.51 M 
D)  0.11 M 
E)  2.0 × 102 M

Question 14

The elementary steps for the catalyzed decomposition for dinitrogen monoxide are shown below.Identify the catalyst. 
NO(g)+ N2O(g)→ N2(g)+ NO2(g)
2NO2(g)→ 2NO(g)+ O2(g)

Accepted Answer

A)  NO(g) 
B)  N2O(g) 
C)  N2(g) 
D)  NO2(g) 
E)  O2(g) 
A)  NO(g) 
B)  N2O(g) 
C)  N2(g) 
D)  NO2(g) 
E)  O2(g)

Question 15

Nitrogen dioxide reacts with carbon monoxide to produce nitrogen monoxide and carbon dioxide. 
$\begin{array}{l}
2 \mathrm{NO}_{2}(g) \rightleftharpoons \mathrm{NO}_{3}(g)+\mathrm{NO}(g) &(fast, equilibrium)\
\mathrm{NO}_{3}(g)+\mathrm{CO}(g) \rightarrow \mathrm{NO}_{2}(g)+\mathrm{CO}_{2}(g)&(slow) 
\end{array}
$

What is a rate law that is consistent with the proposed mechanism?

Accepted Answer

A)  rate = k[NO2]2×[CO]× [NO]-1 
B)  rate = k[NO2]2×[CO] 
C)  rate = k[NO2]×[CO] 
D)  rate = k[NO3]×[CO] 
E)  rate = k[NO2]2 
A)  rate = k[NO2]2×[CO]× [NO]-1 
B)  rate = k[NO2]2×[CO] 
C)  rate = k[NO2]×[CO] 
D)  rate = k[NO3]×[CO] 
E)  rate = k[NO2]2

Question 16

Which equation is used to calculate the half-life of the zero-order equation below?$ \mathrm{A} \rightarrow 2 \mathrm{~B} $$ \quad$$ \quad$$ \quad$$ \quad$$ \quad$$ \quad$$ \quad$rate $ =k $

Accepted Answer

A)  $t_{1 / 2}=\frac{1}{2 k}$ 
B)  $t_{1 / 2}=\frac{[\mathrm{A}]_{0}}{k}$ 
C)  $t_{1 / 2}=\frac{[A]_{0}}{2 k}$ 
D)  $t_{1 / 2}=\frac{k}{[\mathrm{~A}]_{0}}$ 
E)  t1/2 = k 
A)  $t_{1 / 2}=\frac{1}{2 k}$ 
B)  $t_{1 / 2}=\frac{[\mathrm{A}]_{0}}{k}$ 
C)  $t_{1 / 2}=\frac{[A]_{0}}{2 k}$ 
D)  $t_{1 / 2}=\frac{k}{[\mathrm{~A}]_{0}}$ 
E)  t1/2 = k

Question 17

For the second-order reaction below,the concentration of product B after 132 seconds is 0.0281 M.If the initial concentration of A is 0.932 M,what is the rate constant? $2 \mathrm{~A} \rightarrow \mathrm{B} \quad\quad\quad\quad\quad \text { rate }=k[\mathrm{~A}]^{2}$

Accepted Answer

A)  1.43 × 10?5 L/mol?s 
B)  4.71 × 10?4 L/mol?s 
C)  5.22 × 10?4 L/mol?s 
D)  6.63 × 10?3 L/mol?s 
E)  96.4 L/mol?s 
A)  1.43 × 10?5 L/mol?s 
B)  4.71 × 10?4 L/mol?s 
C)  5.22 × 10?4 L/mol?s 
D)  6.63 × 10?3 L/mol?s 
E)  96.4 L/mol?s

Question 18

For the reaction A + 2B ? C,the rate law is $\frac{\Delta[\mathrm{C}]}{\Delta t}=k[\mathrm{~A}]^{2} \times[\mathrm{B}]$ . What are the units of the rate constant where time is measured in seconds?

Accepted Answer

A)  $\frac{1}{\mathrm{~mol} / \mathrm{L} \cdot \mathrm{s}}$ 
B)  $\frac{1}{(\mathrm{~mol} / \mathrm{L})^{2} \cdot \mathrm{s}}$ 
C)  $\frac{1}{\mathrm{~s}}$ 
D)  $\frac{(\mathrm{mol} / \mathrm{L})^{2}}{\mathrm{~s}}$ 
E)  $\frac{\mathrm{mol}}{\mathrm{L} \cdot \mathrm{s}}$ 
A)  $\frac{1}{\mathrm{~mol} / \mathrm{L} \cdot \mathrm{s}}$ 
B)  $\frac{1}{(\mathrm{~mol} / \mathrm{L})^{2} \cdot \mathrm{s}}$ 
C)  $\frac{1}{\mathrm{~s}}$ 
D)  $\frac{(\mathrm{mol} / \mathrm{L})^{2}}{\mathrm{~s}}$ 
E)  $\frac{\mathrm{mol}}{\mathrm{L} \cdot \mathrm{s}}$

Question 19

For the overall reaction A + 2B ? C
Which of the following mechanisms yields the correct overall chemical equation and is consistent with the rate equation below?
Rate = k[A]×[B]

Accepted Answer

A)  
$\begin{array}{l}
\mathrm{A}+\mathrm{B} \rightleftharpoons \mathrm{I} &\text { (fast) } \
\mathrm{I}+\mathrm{A} \rightarrow \mathrm{C} &\text { (slow) }
\end{array}$ 
B)  
$\begin{array}{l}
\mathrm{A}+\mathrm{B} \rightarrow \mathrm{I} &\text { (slow) } \
\mathrm{I}+\mathrm{B} \rightarrow \mathrm{C} &\text { (fast) }
\end{array}$ 
C)  
$\begin{array}{l}
2 \mathrm{~B} \rightarrow \mathrm{I} &\text { (slow) } \
\mathrm{A}+\mathrm{I} \rightarrow \mathrm{C} &\text { (fast) }
\end{array}$ 
D)  
$\begin{array}{l}
2 \mathrm{~B} \rightleftharpoons \mathrm{I}& \text { (fast) } \
\mathrm{I}+\mathrm{A} \rightarrow \mathrm{C} &\text { (slow) }
\end{array}$ 
E) 
$\begin{array}{l}
\mathrm{A}+2 \mathrm{~B} \rightleftharpoons \mathrm{I} &\text { (fast) } \
\mathrm{I}+\mathrm{B} \rightarrow \mathrm{C}+\mathrm{B} &\text { (slow) }
\end{array}$ 
A)  
$\begin{array}{l}
\mathrm{A}+\mathrm{B} \rightleftharpoons \mathrm{I} &\text { (fast) } \
\mathrm{I}+\mathrm{A} \rightarrow \mathrm{C} &\text { (slow) }
\end{array}$ 
B)  
$\begin{array}{l}
\mathrm{A}+\mathrm{B} \rightarrow \mathrm{I} &\text { (slow) } \
\mathrm{I}+\mathrm{B} \rightarrow \mathrm{C} &\text { (fast) }
\end{array}$ 
C)  
$\begin{array}{l}
2 \mathrm{~B} \rightarrow \mathrm{I} &\text { (slow) } \
\mathrm{A}+\mathrm{I} \rightarrow \mathrm{C} &\text { (fast) }
\end{array}$ 
D)  
$\begin{array}{l}
2 \mathrm{~B} \rightleftharpoons \mathrm{I}& \text { (fast) } \
\mathrm{I}+\mathrm{A} \rightarrow \mathrm{C} &\text { (slow) }
\end{array}$ 
E) 
$\begin{array}{l}
\mathrm{A}+2 \mathrm{~B} \rightleftharpoons \mathrm{I} &\text { (fast) } \
\mathrm{I}+\mathrm{B} \rightarrow \mathrm{C}+\mathrm{B} &\text { (slow) }
\end{array}$

Question 20

A first-order reaction has a half-life of 4.54 seconds.How much time is required for the reactant to be reduced to 6.25% of its initial concentration?

Accepted Answer

A)  1.14 s 
B)  9.08 s 
C)  13.6 s 
D)  18.2 s 
E)  93.6 s 
A)  1.14 s 
B)  9.08 s 
C)  13.6 s 
D)  18.2 s 
E)  93.6 s

Exam 11: Rate of Reaction

What is the half-life of a first-order reaction if the rate constant is 6.2 × 10-3 s-1?

For the first-order reaction below,the initial concentration of A is 0.240 M.If the concentration of A decreases to 0.0800 M after 21.8 hours,what is the half-life of the reaction? A→B \mathrm{A} \rightarrow \mathrm{B} A→B \quad \quad \quad \quad \quad rate =k[ A] =k[\mathrm{~A}] =k[ A]

The rate constant for the decomposition of cyclobutane is 2.08 × 10−2 s−1 at high temperatures. C4H8(g)→ 2C2H4(g) How many seconds are required for an initial concentration of 0.100 M C4H8(g)to decrease to 0.0450 M?

Which equation is used to calculate the half-life of the second-order equation below? 2 A→B rate =k[ A]22 \mathrm{~A} \rightarrow \mathrm{B} \quad\quad\quad\quad\quad\quad\quad \text { rate }=k[\mathrm{~A}]^{2}2 A→B rate =k[ A]2

At a high temperature,the first-order decomposition of N2O5(g)produces NO2(g)and O2(g).If the initial concentration of 0.400 M N2O5(g)is reduced to 0.169 M after 118 seconds,what is the rate constant for the reaction?

The correct form of the Arrhenius equation is

The decomposition of formic acid follows first-order kinetics. HCO2H(g)→ CO2(g)+ H2(g) The half-life for the reaction at 550°C is 24 seconds.How many seconds does it take for the formic acid concentration to decrease by 87.5%?

The rate constant of a first-order decomposition reaction is 0.0147 s-1.If the initial concentration of reactant is 0.178 M,what is the concentration of reactant after 30.0 seconds?

The rate constant at 373 K for a certain reaction is 8.29 × 10−4 s−1 and the activation energy is 12.0 kJ/mole.What is the value of the constant,A,in the Arrhenius equation?

What did Henry Eyring develop that changed how scientists study rates of reactions?

The reaction A → B follows first-order kinetics with a half-life of 21.7 hours.If the concentration of A is 0.023 M after 48.0 hours,what is the initial concentration of A?

The elementary steps for the catalyzed decomposition for dinitrogen monoxide are shown below.Identify the catalyst. NO(g)+ N2O(g)→ N2(g)+ NO2(g) 2NO2(g)→ 2NO(g)+ O2(g)

Nitrogen dioxide reacts with carbon monoxide to produce nitrogen monoxide and carbon dioxide. 2(g)\rightleftharpoons(g)+(g) (fast,equilibrium) (g)+(g)\rightarrow(g)+(g) (slow) What is a rate law that is consistent with the proposed mechanism?

Which equation is used to calculate the half-life of the zero-order equation below? A→2 B \mathrm{A} \rightarrow 2 \mathrm{~B} A→2 B \quad \quad \quad \quad \quad \quad \quad rate =k =k =k

For the reaction A + 2B ? C,the rate law is Δ[C]Δt=k[ A]2×[B]\frac{\Delta[\mathrm{C}]}{\Delta t}=k[\mathrm{~A}]^{2} \times[\mathrm{B}]ΔtΔ[C]​=k[ A]2×[B] . What are the units of the rate constant where time is measured in seconds?

For the overall reaction A + 2B ? C Which of the following mechanisms yields the correct overall chemical equation and is consistent with the rate equation below? Rate = k[A]×[B]

A first-order reaction has a half-life of 4.54 seconds.How much time is required for the reactant to be reduced to 6.25% of its initial concentration?

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What is the half-life of a first-order reaction if the rate constant is 6.2 × 10^-3 s^-1?

For the first-order reaction below,the initial concentration of A is 0.240 M.If the concentration of A decreases to 0.0800 M after 21.8 hours,what is the half-life of the reaction? $\mathrm{A} \rightarrow \mathrm{B}$ $\quad$ $\quad$ $\quad$ $\quad$ $\quad$ rate $=k[\mathrm{~A}]$

The rate constant for the decomposition of cyclobutane is 2.08 × 10−² s−¹ at high temperatures. C₄H₈(g)→ 2C₂H₄(g) How many seconds are required for an initial concentration of 0.100 M C₄H₈(g)to decrease to 0.0450 M?

Which equation is used to calculate the half-life of the second-order equation below? $2 \mathrm{~A} \rightarrow \mathrm{B} \quad\quad\quad\quad\quad\quad\quad \text { rate }=k[\mathrm{~A}]^{2}$

At a high temperature,the first-order decomposition of N₂O₅(g)produces NO₂(g)and O₂(g).If the initial concentration of 0.400 M N₂O₅(g)is reduced to 0.169 M after 118 seconds,what is the rate constant for the reaction?

The decomposition of formic acid follows first-order kinetics. HCO₂H(g)→ CO₂(g)+ H₂(g) The half-life for the reaction at 550°C is 24 seconds.How many seconds does it take for the formic acid concentration to decrease by 87.5%?

The rate constant of a first-order decomposition reaction is 0.0147 s^-1.If the initial concentration of reactant is 0.178 M,what is the concentration of reactant after 30.0 seconds?

The rate constant at 373 K for a certain reaction is 8.29 × 10−⁴ s−¹ and the activation energy is 12.0 kJ/mole.What is the value of the constant,A,in the Arrhenius equation?

The elementary steps for the catalyzed decomposition for dinitrogen monoxide are shown below.Identify the catalyst. NO(g)+ N₂O(g)→ N₂(g)+ NO₂(g) 2NO₂(g)→ 2NO(g)+ O₂(g)

Which equation is used to calculate the half-life of the zero-order equation below? $\mathrm{A} \rightarrow 2 \mathrm{~B}$ $\quad$ $\quad$ $\quad$ $\quad$ $\quad$ $\quad$ $\quad$ rate $=k$

For the reaction A + 2B ? C,the rate law is $\frac{\Delta[\mathrm{C}]}{\Delta t}=k[\mathrm{~A}]^{2} \times[\mathrm{B}]$ . What are the units of the rate constant where time is measured in seconds?