AP Chemistry Chemical Kinectics Word Problem – Flashcards
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Matching:
A) activation energy
B) half-life
C) frequency factor
D) reaction order
E) rate constant
1. A
2. n, in Rate = k[A]ⁿ
3. k
4. t₁/₂
5. Ea
answer
1. c
2. d
3. e
4. b
5. a
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1. What happens in the concentration of reactants and products during a chemical reaction?
answer
The concentrations change over time. Typically, reactants decrease and products increase if it is a forward reaction.
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2. Is the activation energy for a forward reaction the same as the activation energy for the reverse of the same reaction? Use a sketch of a reaction energy diagram.
answer
Not typically. see sketch
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3. Define activation energy
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An energy barrier that must be surmounted for the reactants to be transformed into products
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4. Define half-life
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The time required for the concentration of a reactant to fall to one-half of its initial value
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5. What is the difference between average reaction rate and instantaneous reaction rate?
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Average is over time, while instantaneous is rate at a particular time
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6. What is a catalyst and what function does it serve?
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A substance that increases the rate of a chemical reaction but is not consumed by the reaction
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7. What function do enzymes serve?
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Biological catalysts that increase the rate of a chemical reaction but is not consumed by the reaction
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8. Define the frequency factor
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the number of times that the reactants approach the activation barrier per unit time
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9. Explain what the exponential factor in the Arrhenius equation represents.
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a number between 0 and 1 that represents the fraction of molecules that have enough energy to make it over the activation barrier on a given approach
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10. Explain how the order of a reaction can be determined.
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only by experiment. measure of initial rates = running the reaction several times with the different initial reactant concentrations to determine the effect of concentration on rate
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3. What are the units of k in a first order reaction?
a. M²/s²
b. M
c. M⁻¹s⁻¹
d. 1/s
e. M/s
answer
d
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8. Which of the following represents the integrated rate law for a zeroth-order reaction?
a. ln(k₂/k₁) = Ea/R(1/T) + lnA
b. ln([A]t/[A]₀) = -kt
c. 1/[A]t - 1/[A]₀ = kt
d. k = Ae^(-Ea/RT)
e. [A]t - [A]₀ = -kt
answer
e
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20. In the hydrogenation of double bonds, a catalyst is needed. In the last step, the reactants must escape from the surface into the gas phase. This step is known as _____.
a. desorption
b. diffusion
c. reaction
d. adsorption
e. none of the above
answer
a
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22. Give the characteristic of a zero order reaction having only one reactant.
a. The rate of the reaction is proportional to the square root of the concentration of the reactant.
b. The rate of the reaction is directly proportional to the concentration of the reactant.
c. The rate of the reaction is proportional to the square of the concentration of the reactant.
d. The rate of the reaction is proportional to the natural logarithm of the concentration of the reactant.
e. The rate of the reaction is not proportional to the concentration of the reactant.
answer
e
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28. For a reaction, what generally happens if the temperature is increased?
a. an increase in k occurs, which results in a faster rate
b. a decrease in k occurs, which results in a slower rate
c. an increase in k occurs, which results in a slower rate
d. there is no change with k or the rate
e. a decrease in k occurs, which results in a faster rate
answer
a
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30. Which rate law is bimolecular?
a. rate = k[A]³
b. rate = k[A][B]³
c. rate = k[A][B][C][D]
d. rate = k[A]²[B]²
e. rate = k[A][B]
answer
e
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37. Identify a homogeneous catalyst
a. SO₂ over vandium (V) oxide
b. N₂ and H₂ catalyzed by Fe
c. H₂SO₄ with concentrated HCl
d. Pd in H₂ gas
e. Pt with methane
answer
c
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47. What are the units of k in a second order reaction?
a. M²/s
b. M/s
c. M
d. M⁻¹s⁻¹
e. 1/M
answer
d
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49. Biological catalysts that increase the rates of biochemical reactions are known as _____.
a. binders
b. substrates
c. enzymes
d. trumanettes
e. inhibitors
answer
c
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52. Give the characteristic of a first order reaction having only one reactant.
a. the rate of the reaction is proportional to the square root of the concentration of the reactant
b. the rate of the reaction is directly proportional to the concentration of the reactant
c. the rate of the reaction is not proportional to the concentration of the reactant
d. the rate of the reaction is proportional to the natural logarithm of the concentration of the reactant
e. the rate of the reaction is proportional to the square of the concentration of the reactant
answer
b
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54. Which rate law is termolecular?
a. rate = k[A][B][C][D]
b. rate = k[A]⁵
c. rate = k[A][B]³
d. rate = k[A][B]²
e. rate = k[A]²
answer
d
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59. Which of the following reactions would you predict to have the smallest orientation factor?
a. N + O2 → NO₂
b. NOCl₂ + NO → 2NOCl
c. X₂ + Y₂→ 2XY
d. N₂ +O₂→2NO
e. all of these reactions should have nearly identical orientation factors
answer
b
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61. What data should be plotted to show that experimental concentration data fits a zeroth-order reaction?
a. ln[reactant] vs time
b. 1/[reactant] vs time
c. ln(k) vs Ea
d. [reactant] vs time
e. ln(k) vs 1/T
answer
d
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63. Give the characteristic of a second order reaction having only one reactant
a. the rate of the reaction is not proportional to the concentration of the reactant
b. the rate of the reaction is proportional to the natural logarithm of the concentration of the reactant
c. the rate of the reaction is proportional to the square root of the concentration of the reactant
d. the rate of the reaction is directly proportional to the concentration of the reactant
e. the rate of the reaction is proportional to the square of the concentration of the reactant
answer
e
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68. What are the units of k in a zero order reaction?
a. M2/s
b. M⁻1/s⁻1
c. s/M
d. M/s
e. M
answer
d
