Chapter 12- Kinetics

Question 1 of 36

1

At elevated temperatures, dinitrogen pentoxide decomposes to nitrogen dioxide and oxygen:

2N2O5(g) → 4NO2 (g) + O2 (g)

When the rate of formation of O2 is 2.2 × 10-4 M/s, the rate of decomposition of N2O5 is __________ M/s.

Select one of the following:

A) 1.1 × 10-4
B) 2.2 × 10-4
C) 2.8 × 10-4
D) 4.4 × 10-4
E) 5.5 × 10-4

Explanation

Question 2 of 36

1

Which one of the following is not a valid expression for the rate of the reaction below?

4NH3 + 7O2 → 4NO2 + 6H2O

Select one of the following:

A)
B)
C)
D)
E) All of the above are valid expressions of the reaction rate.

Explanation

Question 3 of 36

1

The rate law of a reaction is rate = k[D][X]. The units of the rate constant are __________.

Select one of the following:

A) mol L-1s-1
B) L mol-1s-1
C) mol2 L-2s-1
D) mol L-1s-2
E) L2 mol -2s-1

Explanation

Question 4 of 36

1

The rate law for this reaction is rate = __________.

Select one of the following:

A) k[A][B]
B) k[P]
C) k[A]2[B]
D) k[A]2[B]2
E) k[A]2

Explanation

Question 5 of 36

1

Under constant conditions, the half-life of a first-order reaction __________.

Select one of the following:

A) is the time necessary for the reactant concentration to drop to half its original value
B) is constant
C) can be calculated from the reaction rate constant
D) does not depend on the initial reactant concentration
E) All of the above are correct.

Explanation

Question 6 of 36

1

The reaction

2NO2 → 2NO + O2

follows second-order kinetics. At 300°C, [NO2] drops from 0.0100 M to 0.00650 M in 100.0 s. The rate constant for the reaction is __________ M-1s-1.

Select one of the following:

A) 0.096
B) 0.65
C) 0.81
D) 1.2
E) 0.54

Explanation

Question 7 of 36

1

A compound decomposes by a first-order process. If 25.0% of the compound decomposes in 60.0 minutes, the half-life of the compound is __________.

Select one of the following:

A) 65 minutes
B) 120 minutes
C) 145 minutes
D) 180 minutes
E) 198 minutes

Explanation

Question 8 of 36

1

The following reaction is second order in [A] and the rate constant is 0.025 M-1s-1:

A → B

The concentration of A was 0.65 M at 33 s. The initial concentration of A was __________ M.

Select one of the following:

A) 2.4
B) 0.27
C) 0.24
D) 1.4
E) 1.2 × 10-2

Explanation

Question 9 of 36

1

The rate constant for this reaction is __________ s-1.

Select one of the following:

A) 6.9 × 10-2
B) 3.0 × 10-2
C) 14
D) 0.46
E) 4.0 × 102

Explanation

Question 10 of 36

1

The concentration of A is __________ M after 40.0 s.

Select one of the following:

A) 1.3 × 10-2
B) 1.2
C) 0.17
D) 3.5 × 10-4
E) 0.025

Explanation

Question 11 of 36

1

The rate constant of a first-order process that has a half-life of 225 s is __________s-1.

Select one of the following:

A) 0.693
B) 3.08 × 10-3
C) 1.25
D) 12.5
E) 4.44 × 10-3

Explanation

Question 12 of 36

1

One difference between first- and second-order reactions is that __________.

Select one of the following:

A) the half-life of a first-order reaction does not depend on [A]0; the half-life of a second-order reaction does depend on [A]0
B) the rate of both first-order and second-order reactions do not depend on reactant concentrations
C) the rate of a first-order reaction depends on reactant concentrations; the rate of a second-order reaction does not depend on reactant concentrations
D) a first-order reaction can be catalyzed; a second-order reaction cannot be catalyzed
E) None of the above are true.

Explanation

Question 13 of 36

1

At elevated temperatures, methylisonitrile (CH3NC) isomerizes to acetonitrile (CH3CN):

CH3NC (g) → CH3CN (g)

The reaction is first order in methylisonitrile. The attached graph shows data for the reaction obtained at 198.9°C.

The rate constant for the reaction is __________ s-1.

Select one of the following:

A) -1.9 × 104
B) +1.9 × 104
C) -5.2 × 10-5
D) +5.2 × 10-5
E) +6.2

Explanation

Question 14 of 36

1

The decomposition of N2O5 in solution in carbon tetrachloride proceeds via the reaction

2N2O5 (soln) → 4NO2 (soln) + O2 (soln)

The reaction is first order and has a rate constant of 4.82 × 10-3 s-1 at 64°C. The rate law for the reaction is rate = __________.

Select one of the following:

A) k[N2O5]2
B)
C) k[N2O5]
D)
E)2k[N2O5]

Explanation

Question 15 of 36

1

As the temperature of a reaction is increased, the rate of the reaction increases because the __________.

Select one of the following:

A) reactant molecules collide less frequently
B) reactant molecules collide more frequently and with greater energy per collision
C) activation energy is lowered
D) reactant molecules collide less frequently and with greater energy per collision
E) reactant molecules collide more frequently with less energy per collision

Explanation

Question 16 of 36

1

The rate of a reaction depends on __________.

Select one of the following:

A) collision frequency
B) collision energy
C) collision orientation
D) all of the above
E) none of the above

Explanation

Question 17 of 36

1

Which energy difference in the energy profile below corresponds to the activation energy for the forward reaction?

Select one of the following:

A) x
B) y
C) x + y
D) x - y
E) y – x

Explanation

Question 18 of 36

1

In the energy profile of a reaction, the species that exists at the maximum on the curve is called the __________.

Select one of the following:

A) product
B) activated complex
C) activation energy
D) enthalpy of reaction
E) atomic state

Explanation

Question 19 of 36

1

In general, as temperature goes up, reaction rate __________.

Select one of the following:

A) goes up if the reaction is exothermic
B) goes up if the reaction is endothermic
C) goes up regardless of whether the reaction is exothermic or endothermic
D) stays the same regardless of whether the reaction is exothermic or endothermic
E) stays the same if the reaction is first order

Explanation

Question 20 of 36

1

At elevated temperatures, methylisonitrile (CH3NC) isomerizes to acetonitrile (CH3CN):

CH3NC (g) → CH3CN (g)

The dependence of the rate constant on temperature is studied and the graph below is prepared from the results.

The energy of activation of this reaction is __________ kJ/mol.

Select one of the following:

A) 160
B) 1.6 × 105
C) 4.4 × 10-7
D) 4.4 × 10-4
E) 1.9 × 104

Explanation

Question 21 of 36

1

The mechanism for formation of the product X is:

A + B → C + D (slow)
B + D → X (fast)

The intermediate reactant in the reaction is __________.

Select one of the following:

A) A
B) B
C) C
D) D
E) X

Explanation

Question 22 of 36

1

Which of the following is true?

Select one of the following:

A) If we know that a reaction is an elementary reaction, then we know its rate law.
B) The rate-determining step of a reaction is the rate of the fastest elementary step of its mechanism.
C) Since intermediate compounds can be formed, the chemical equations for the elementary reactions in a multistep mechanism do not always have to add to give the chemical equation of the overall process.
D) In a reaction mechanism, an intermediate is identical to an activated complex.
E) All of the above statements are true.

Explanation

Question 23 of 36

1

Of the following, __________ will lower the activation energy for a reaction.

Select one of the following:

A) increasing the concentrations of reactants
B) raising the temperature of the reaction
C) adding a catalyst for the reaction
D) removing products as the reaction proceeds
E) increasing the pressure

Explanation

Question 24 of 36

1

A catalyst can increase the rate of a reaction __________.

Select one of the following:

A) by changing the value of the frequency factor (A)
B) by increasing the overall activation energy (Ea) of the reaction
C) by lowering the activation energy of the reverse reaction
D) by providing an alternative pathway with a lower activation energy
E) All of these are ways that a catalyst might act to increase the rate of reaction.

Explanation

Question 25 of 36

1

Nitrogen fixation is a difficult process because __________.

Select one of the following:

A) there is so little nitrogen in the atmosphere
B) nitrogen exists in the atmosphere primarily as its oxides which are very unreactive
C) nitrogen is very unreactive, largely due to its triple bond
D) of the extreme toxicity of nitrogen
E) of the high polarity of nitrogen molecules preventing them from dissolving in biological fluids, such as those inside cells

Explanation

Question 26 of 36

1

Consider the following reaction:

3A → 2B

The average rate of appearance of B is given by Δ[B]/Δt. Comparing the rate of appearance of B and the rate of disappearance of A, we get Δ[B]/Δt = __________ × (-Δ[A]/Δt).

Select one of the following:

A) -2/3
B) +2/3
C) -3/2
D) +1
E) +3/2

Explanation

Question 27 of 36

1

Which substance in the reaction below either appears or disappears the fastest?

4NH3 + 7O2 → 4NO2 + 6H2O

Select one of the following:

A) NH3
B) O2
C) NO2
D) H2O
E) The rates of appearance/disappearance are the same for all of these.

Explanation

Question 28 of 36

1

A flask is charged with 0.124 mol of A and allowed to react to form B according to the reaction A(g) →B(g). The following data are obtained for [A] as the reaction proceeds:

The average rate of disappearance of A between 10 s and 20 s is __________ mol/s.

Select one of the following:

A) 2.2 × 10-3
B) 1.1 × 10-3
C) 4.4 × 10-3
D) 454
E) 9.90 × 10-3

Explanation

Question 29 of 36

1

A flask is charged with 0.124 mol of A and allowed to react to form B according to the reaction A(g) →B(g). The following data are obtained for [A] as the reaction proceeds:

The average rate of appearance of B between 20 s and 30 s is __________ mol/s.

Select one of the following:

A) +1.5 × 10-3
B) +5.0 × 10-4
C) -1.5 × 10-3
D) +7.3 × 10-3
E) -7.3 × 10-3

Explanation

Question 30 of 36

1

A reaction was found to be second order in carbon monoxide concentration. The rate of the reaction __________ if the [CO] is doubled, with everything else kept the same.

Select one of the following:

A) doubles
B) remains unchanged
C) triples
D) increases by a factor of 4
E) is reduced by a factor of 2

Explanation

Question 31 of 36

1

The half-life of a first-order reaction is 13 min. If the initial concentration of reactant is 0.085 M, it takes __________ min for it to decrease to 0.055 M.

Select one of the following:

A) 8.2
B) 11
C) 3.6
D) 0.048
E) 8.4

Explanation

Question 32 of 36

1

A second-order reaction has a half-life of 18 s when the initial concentration of reactant is 0.71 M. The rate constant for this reaction is __________ M-1s-1.

Select one of the following:

A) 7.8 × 10-2
B) 3.8 × 10-2
C) 2.0 × 10-2
D) 1.3
E) 18

Explanation

Question 33 of 36

1

The rate of disappearance of HBr in the gas phase reaction

2HBr (g) → H2 (g) + Br2 (g)

is 0.130 Ms-1 at 150°C. The rate of reaction is __________ Ms-1.

Select one of the following:

A) 3.85
B) 0.0650
C) 0.0169
D) 0.260
E) 0.0860

Explanation

Question 34 of 36

1

Nitrogen dioxide decomposes to nitric oxide and oxygen via the reaction:

2NO2 → 2NO + O2

In a particular experiment at 300 °C, [NO2] drops from 0.0100 to 0.00550 M in 100 s. The rate of appearance of O2 for this period is __________ M/s.

Select one of the following:

A) 2.3 × 10-5
B) 4.5 × 10-5
C) 9.0 × 10-5
D) 4.5 × 10-3
E) 9.0 × 10-3

Explanation

Question 35 of 36

1

The reaction

2NOBr (g) → 2 NO (g) + Br2 (g)

is a second-order reaction with a rate constant of 0.80 M-1s-1 at 11°C. If the initial concentration of NOBr is 0.0440 M, the concentration of NOBr after 7.0 seconds is __________.

Select one of the following:

A) 0.0276 M
B) 0.0324 M
C) 0.0353 M
D) 0.0480 M
E) 0.0402 M

Explanation

Question 36 of 36

1

A particular first-order reaction has a rate constant of 1.35 × 102s-1 at 25.0°C. What is the magnitude of k at 95.0°C if Ea = 55.5 kJ/mol?

Select one of the following:

A) 9.56 × 103
B) 2.85 × 104
C) 576
D) 4.33 × 1087
E) 1.36 × 102

	Created by Dawn G almost 8 years ago

Originally chapter 14

Chapter 12- Kinetics

Question 1 of 36

At elevated temperatures, dinitrogen pentoxide decomposes to nitrogen dioxide and oxygen: 2N2O5(g) → 4NO2 (g) + O2 (g) When the rate of formation of O2 is 2.2 × 10-4 M/s, the rate of decomposition of N2O5 is __________ M/s.

Select one of the following:

Explanation

Question 2 of 36

Which one of the following is not a valid expression for the rate of the reaction below? 4NH3 + 7O2 → 4NO2 + 6H2O

Select one of the following:

Explanation

Question 3 of 36

The rate law of a reaction is rate = k[D][X]. The units of the rate constant are __________.

Select one of the following:

Explanation

Question 4 of 36

The rate law for this reaction is rate = __________.

Select one of the following:

Explanation

Question 5 of 36

Under constant conditions, the half-life of a first-order reaction __________.

Select one of the following:

Explanation

Question 6 of 36

The reaction 2NO2 → 2NO + O2 follows second-order kinetics. At 300°C, [NO2] drops from 0.0100 M to 0.00650 M in 100.0 s. The rate constant for the reaction is __________ M-1s-1.

Select one of the following:

Explanation

Question 7 of 36

A compound decomposes by a first-order process. If 25.0% of the compound decomposes in 60.0 minutes, the half-life of the compound is __________.

Select one of the following:

Explanation

Question 8 of 36

The following reaction is second order in [A] and the rate constant is 0.025 M-1s-1: A → B The concentration of A was 0.65 M at 33 s. The initial concentration of A was __________ M.

Select one of the following:

Explanation

Question 9 of 36

The rate constant for this reaction is __________ s-1.

Select one of the following:

Explanation

Question 10 of 36

The concentration of A is __________ M after 40.0 s.

Select one of the following:

Explanation

Question 11 of 36

The rate constant of a first-order process that has a half-life of 225 s is __________s-1.

Select one of the following:

Explanation

Question 12 of 36

One difference between first- and second-order reactions is that __________.

Select one of the following:

Explanation

Question 13 of 36

At elevated temperatures, methylisonitrile (CH3NC) isomerizes to acetonitrile (CH3CN): CH3NC (g) → CH3CN (g) The reaction is first order in methylisonitrile. The attached graph shows data for the reaction obtained at 198.9°C. The rate constant for the reaction is __________ s-1.

Select one of the following:

Explanation

Question 14 of 36

The decomposition of N2O5 in solution in carbon tetrachloride proceeds via the reaction 2N2O5 (soln) → 4NO2 (soln) + O2 (soln) The reaction is first order and has a rate constant of 4.82 × 10-3 s-1 at 64°C. The rate law for the reaction is rate = __________.

Select one of the following:

Explanation

Question 15 of 36

As the temperature of a reaction is increased, the rate of the reaction increases because the __________.

Select one of the following:

Explanation

Question 16 of 36

The rate of a reaction depends on __________.

Select one of the following:

Explanation

Question 17 of 36

Which energy difference in the energy profile below corresponds to the activation energy for the forward reaction?

Select one of the following:

Explanation

Question 18 of 36

In the energy profile of a reaction, the species that exists at the maximum on the curve is called the __________.

Select one of the following:

Explanation

Question 19 of 36

In general, as temperature goes up, reaction rate __________.

Select one of the following:

Explanation

Question 20 of 36

At elevated temperatures, methylisonitrile (CH3NC) isomerizes to acetonitrile (CH3CN): CH3NC (g) → CH3CN (g) The dependence of the rate constant on temperature is studied and the graph below is prepared from the results. The energy of activation of this reaction is __________ kJ/mol.

At elevated temperatures, dinitrogen pentoxide decomposes to nitrogen dioxide and oxygen:

2N2O5(g) → 4NO2 (g) + O2 (g)

When the rate of formation of O2 is 2.2 × 10-4 M/s, the rate of decomposition of N2O5 is __________ M/s.

Which one of the following is not a valid expression for the rate of the reaction below?

4NH3 + 7O2 → 4NO2 + 6H2O

The reaction

2NO2 → 2NO + O2

follows second-order kinetics. At 300°C, [NO2] drops from 0.0100 M to 0.00650 M in 100.0 s. The rate constant for the reaction is __________ M-1s-1.

The following reaction is second order in [A] and the rate constant is 0.025 M-1s-1:

A → B

The concentration of A was 0.65 M at 33 s. The initial concentration of A was __________ M.

At elevated temperatures, methylisonitrile (CH3NC) isomerizes to acetonitrile (CH3CN):

CH3NC (g) → CH3CN (g)

The reaction is first order in methylisonitrile. The attached graph shows data for the reaction obtained at 198.9°C.

The rate constant for the reaction is __________ s-1.

The decomposition of N2O5 in solution in carbon tetrachloride proceeds via the reaction

2N2O5 (soln) → 4NO2 (soln) + O2 (soln)

The reaction is first order and has a rate constant of 4.82 × 10-3 s-1 at 64°C. The rate law for the reaction is rate = __________.

At elevated temperatures, methylisonitrile (CH3NC) isomerizes to acetonitrile (CH3CN):

CH3NC (g) → CH3CN (g)

The dependence of the rate constant on temperature is studied and the graph below is prepared from the results.

The energy of activation of this reaction is __________ kJ/mol.

The mechanism for formation of the product X is:

A + B → C + D (slow)
B + D → X (fast)

The intermediate reactant in the reaction is __________.

Consider the following reaction:

3A → 2B

The average rate of appearance of B is given by Δ[B]/Δt. Comparing the rate of appearance of B and the rate of disappearance of A, we get Δ[B]/Δt = __________ × (-Δ[A]/Δt).

Which substance in the reaction below either appears or disappears the fastest?

4NH3 + 7O2 → 4NO2 + 6H2O

A flask is charged with 0.124 mol of A and allowed to react to form B according to the reaction A(g) →B(g). The following data are obtained for [A] as the reaction proceeds:

The average rate of disappearance of A between 10 s and 20 s is __________ mol/s.

A flask is charged with 0.124 mol of A and allowed to react to form B according to the reaction A(g) →B(g). The following data are obtained for [A] as the reaction proceeds:

The average rate of appearance of B between 20 s and 30 s is __________ mol/s.

The rate of disappearance of HBr in the gas phase reaction

2HBr (g) → H2 (g) + Br2 (g)

is 0.130 Ms-1 at 150°C. The rate of reaction is __________ Ms-1.

Nitrogen dioxide decomposes to nitric oxide and oxygen via the reaction:

2NO2 → 2NO + O2

In a particular experiment at 300 °C, [NO2] drops from 0.0100 to 0.00550 M in 100 s. The rate of appearance of O2 for this period is __________ M/s.

The reaction

2NOBr (g) → 2 NO (g) + Br2 (g)

is a second-order reaction with a rate constant of 0.80 M-1s-1 at 11°C. If the initial concentration of NOBr is 0.0440 M, the concentration of NOBr after 7.0 seconds is __________.