Chapter 12- Kinetics

Pregunta 1 de 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.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 2 de 36

1

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

4NH3 + 7O2 → 4NO2 + 6H2O

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 3 de 36

1

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

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 4 de 36

1

The rate law for this reaction is rate = __________.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 5 de 36

1

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

Selecciona una de las siguientes respuestas posibles:

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.

Explicación

Pregunta 6 de 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.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 7 de 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 __________.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 8 de 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.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 9 de 36

1

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

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 10 de 36

1

The concentration of A is __________ M after 40.0 s.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 11 de 36

1

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

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 12 de 36

1

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

Selecciona una de las siguientes respuestas posibles:

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.

Explicación

Pregunta 13 de 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.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 14 de 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 = __________.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 15 de 36

1

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

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 16 de 36

1

The rate of a reaction depends on __________.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 17 de 36

1

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

Selecciona una de las siguientes respuestas posibles:

A) x
B) y
C) x + y
D) x - y
E) y – x

Explicación

Pregunta 18 de 36

1

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

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 19 de 36

1

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

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 20 de 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.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 21 de 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 __________.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 22 de 36

1

Which of the following is true?

Selecciona una de las siguientes respuestas posibles:

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.

Explicación

Pregunta 23 de 36

1

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

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 24 de 36

1

A catalyst can increase the rate of a reaction __________.

Selecciona una de las siguientes respuestas posibles:

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.

Explicación

Pregunta 25 de 36

1

Nitrogen fixation is a difficult process because __________.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 26 de 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).

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 27 de 36

1

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

4NH3 + 7O2 → 4NO2 + 6H2O

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 28 de 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.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 29 de 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.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 30 de 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.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 31 de 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.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 32 de 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.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 33 de 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.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 34 de 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.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 35 de 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 __________.

Selecciona una de las siguientes respuestas posibles:

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

Explicación

Pregunta 36 de 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?

Selecciona una de las siguientes respuestas posibles:

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

	Creado por Dawn G hace casi 8 años

Originally chapter 14

Chapter 12- Kinetics

Pregunta 1 de 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.

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 2 de 36

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

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 3 de 36

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

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 4 de 36

The rate law for this reaction is rate = __________.

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 5 de 36

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

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 6 de 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.

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 7 de 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 __________.

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 8 de 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.

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 9 de 36

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

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 10 de 36

The concentration of A is __________ M after 40.0 s.

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 11 de 36

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

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 12 de 36

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

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 13 de 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.

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 14 de 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 = __________.

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 15 de 36

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

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 16 de 36

The rate of a reaction depends on __________.

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 17 de 36

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

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 18 de 36

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

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 19 de 36

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

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 20 de 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 __________.