Kinetics Practice Test
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____ 1. The equation H2(g) + I2(g) 2HI(g) is a(n)
a.
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overall reaction.
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c.
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reaction pathway.
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b.
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reaction mechanism.
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d.
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intermediate reaction.
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____ 2. What is the sequence of steps in a reaction called?
a.
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heterogeneous reaction
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c.
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overall reaction
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b.
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rate law
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d.
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reaction mechanism
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____ 3. Most steps in a reaction mechanism
a.
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are complicated.
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c.
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are easily observable.
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b.
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involve several molecules.
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d.
|
are simple.
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____ 4. In the reaction represented by the following equation, a possible intermediate is H2(g) + I2(g) 2HI(g)
a.
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H2.
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c.
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H2I.
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b.
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HI.
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d.
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I2.
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____ 5. Reactions whose reactants and products exist in a single phase are called
a.
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reaction mechanisms.
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c.
|
homogeneous reactions.
|
b.
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heterogeneous reactions.
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d.
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activated complexes.
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____ 6. To react, gas particles must
a.
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be in the same physical state.
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c.
|
have different energies.
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b.
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have the same energy.
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d.
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collide.
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____ 7. To be effective, a collision requires
a.
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sufficient energy.
|
b.
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a favorable orientation.
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c.
|
sufficient energy and a favorable orientation.
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d.
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a reaction mechanism.
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____ 8. Which attempts to explain chemical reactions and physical interactions of molecules?
a.
|
chemical kinetics
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c.
|
thermodynamics
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b.
|
collision theory
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d.
|
thermochemistry
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____ 9. Raising the temperature of gas particles
a.
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increases both collision energy and favorability of orientation.
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b.
|
increases neither collision energy nor favorability of orientation.
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c.
|
increases collision energy but does not increase favorability of orientation.
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d.
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increases favorability of orientation but does not increase collision energy.
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____ 10. If a collision between molecules is very gentle, the molecules are
a.
|
more likely to be favorably oriented.
|
b.
|
less likely to be favorably oriented.
|
c.
|
more likely to react.
|
d.
|
more likely to rebound without reacting.
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____ 11. The minimum energy required for an effective collision is called
a.
|
energy of enthalpy.
|
c.
|
free energy.
|
b.
|
activation energy.
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d.
|
kinetic energy.
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____ 12. A short-lived structure formed during a collision is a(n)
a.
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reagent.
|
c.
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activated complex.
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b.
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catalyst.
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d.
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inhibitor.
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____ 13. The bonding of the activated complex is characteristic of
a.
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reactants only.
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c.
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both reactants and products.
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b.
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products only.
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d.
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solids only.
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____ 14. An activated complex
a.
|
always separates into the products.
|
b.
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always re-forms the reactants.
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c.
|
may either separate into the products or re-form the reactants.
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d.
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always evaporates.
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____ 15. In a diagram of an activated complex, broken lines represent
a.
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actual bonds.
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c.
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electrons.
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b.
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partial bonds.
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d.
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bond energies.
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____ 16. What takes place in an activated complex?
a.
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Bonds form.
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b.
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Bonds break.
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c.
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Some bonds form and other bonds break.
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d.
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A catalyst is produced.
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____ 17. Raising the temperature of reactants in a system
a.
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increases the average kinetic energy of the molecules.
|
b.
|
decreases the average kinetic energy of the molecules.
|
c.
|
decreases the rate of collision of molecules.
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d.
|
has no effect on the average kinetic energy of molecules.
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____ 18. If a collision between molecules is oriented properly, the molecules are
a.
|
more likely to react.
|
c.
|
less likely to form an intermediate.
|
b.
|
more likely to rebound without interacting.
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d.
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less likely to react.
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____ 19. Which statement correctly describes the energy changes that occur when bonds form and when bonds break?
a.
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Breaking bonds is endothermic, and forming bonds is exothermic.
|
b.
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Breaking bonds is exothermic, and forming bonds is endothermic.
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c.
|
Both are exothermic.
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d.
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Both are endothermic.
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____ 20. is positive for
a.
|
an endothermic reaction.
|
c.
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an inhibited reaction.
|
b.
|
an exothermic reaction.
|
d.
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a stable reaction.
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____ 21. Which term has the same numerical value for the forward reaction as it has for the reverse reaction but with opposite sign?
____ 22. Which of the following is true in an endothermic reaction?
a.
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energy of products < activation energy < energy of reactants
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b.
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energy of reactants < activation energy < energy of products
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c.
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energy of products < energy of reactants < activation energy
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d.
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energy of reactants < energy of products < activation energy
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____ 23. Which branch of chemistry studies reaction rates?
a.
|
thermochemistry
|
c.
|
chemical kinetics
|
b.
|
thermodynamics
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d.
|
calorimetry
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____ 24. Which branch of chemistry studies reaction mechanisms?
a.
|
thermochemistry
|
c.
|
chemical kinetics
|
b.
|
thermodynamics
|
d.
|
calorimetry
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____ 25. The usual condition for reaction, a favorable orientation, is not necessary for
a.
|
synthesis reactions.
|
c.
|
single-displacement reactions.
|
b.
|
decomposition reactions.
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d.
|
double-displacement reactions.
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____ 26. How fast something changes with time is a(n)
a.
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area.
|
c.
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order.
|
b.
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rate.
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d.
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collision.
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____ 27. Reaction rate depends upon
a.
|
both collision frequency and efficiency.
|
b.
|
average kinetic energy.
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c.
|
collision efficiency.
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d.
|
average potential energy.
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____ 28. Which of the following affects reaction rate?
a.
|
the nature of reactants
|
c.
|
temperature
|
b.
|
surface area of reactants
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d.
|
All of the above
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____ 29. The decrease in reactant concentration per unit time in a reaction is a measure of the
a.
|
reaction rate.
|
c.
|
overall reaction.
|
b.
|
heterogeneous reaction.
|
d.
|
reaction mechanism.
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____ 30. If the surface area of reactants is larger,
a.
|
the reaction rate is generally higher.
|
b.
|
the reaction rate is generally lower.
|
c.
|
the reaction rate is not affected.
|
d.
|
the rate-determining step is eliminated.
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____ 31. In heterogeneous reactions, the reactants
a.
|
have unequal masses.
|
c.
|
have unequal volumes.
|
b.
|
are not equally reactive.
|
d.
|
are in different phases.
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____ 32. If the temperature of the reactants is lower,
a.
|
the reaction rate is generally higher.
|
b.
|
the reaction rate is generally lower.
|
c.
|
the reaction rate is not affected.
|
d.
|
the rate-determining step is eliminated.
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____ 33. Changing the pressure of a gas is another way of changing its
a.
|
temperature.
|
c.
|
surface area.
|
b.
|
concentration.
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d.
|
composition.
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____ 34. Doubling the pressure of a gas
a.
|
increases the concentration by a factor of two.
|
b.
|
reduces the concentration by a factor of two.
|
c.
|
doesn't affect the concentration.
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d.
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reduces the concentration by a factor of four.
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____ 35. Which process is used to speed up chemical reactions?
a.
|
calorimetry
|
c.
|
activation
|
b.
|
catalysis
|
d.
|
inhibition
|
____ 36. Catalysts generally affect chemical reactions by
a.
|
increasing the temperature of the system.
|
b.
|
increasing the surface area of the reactants.
|
c.
|
providing an alternate pathway with a lower activation energy.
|
d.
|
providing an alternate pathway with a higher activation energy.
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____ 37. A substance that slows down chemical processes is called a(n)
a.
|
inhibitor.
|
c.
|
catalyst.
|
b.
|
reactant.
|
d.
|
indicator.
|
____ 38. How is a heterogeneous catalyst different from the reactants in a chemical reaction?
a.
|
The mass of the catalyst is different.
|
b.
|
The chemical properties of the catalyst are different.
|
c.
|
The energy of the catalyst is different.
|
d.
|
The phase of the catalyst is different.
|
____ 39. In a net equation, catalysts
a.
|
are shown with the reactants.
|
b.
|
are shown with the products.
|
c.
|
are shown with both reactants and products.
|
d.
|
are not shown.
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____ 40. A rate law relates
a.
|
reaction rate and temperature.
|
b.
|
reaction rate and concentrations of reactants.
|
c.
|
temperature and concentrations of reactants.
|
d.
|
energy and concentrations of reactants.
|
____ 41. The letter R in a rate law stands for
a.
|
a proportionality constant.
|
c.
|
temperature.
|
b.
|
concentration.
|
d.
|
reaction rate.
|
____ 42. The value of k in a rate law
a.
|
is the same under all conditions.
|
c.
|
varies with time.
|
b.
|
varies with concentration.
|
d.
|
varies with temperature.
|
____ 43. How are the units for a rate always expressed?
____ 44. In the rate law for the following equation, R=k[A]n[B]m, the units for [A] and [B] are
a.
|
g-1s-1.
|
c.
|
M.
|
b.
|
M-1s-1.
|
d.
|
Ms-1.
|
____ 45. In the rate law for the following equation, R=k[A]n[B]m, the unit for R is
a.
|
g-1s-1.
|
c.
|
M.
|
b.
|
M-1s-1.
|
d.
|
Ms-1.
|
____ 46. A reaction is zero order in reactant A and second order in reactant B. What happens to the reaction rate when the concentrations of both reactants are doubled?
a.
|
The reaction rate remains the same.
|
b.
|
The reaction rate increases by a factor of two.
|
c.
|
The reaction rate increases by a factor of four.
|
d.
|
The reaction rate increases by a factor of eight.
|
____ 47. The rate law for a reaction generally depends most directly on the
a.
|
net chemical reaction.
|
c.
|
rate-determining step.
|
b.
|
first step in the reaction pathway.
|
d.
|
last step in the reaction pathway.
|
____ 48. The rate for a reaction between reactants L, M, and N is proportional to the cube of [L] and the square of [M]. What is the rate law for this reaction?
a.
|
R = k[3L][2M]
|
c.
|
R = k[L]3[M]2
|
b.
|
R = k[L]3[M]2[N]
|
d.
|
R = k[3L][2M][N]
|
____ 49. A transition structure that results from an effective energetic collision between reactants is the —
a.
|
order of the reaction
|
b.
|
rate law
|
c.
|
overall reaction
|
d.
|
activated complex
|
____ 50. How does the potential energy of the activated complex compare with the energies of the reactants and products?
a.
|
It is less than both the energy of the reactants and the energy of the products.
|
b.
|
It is less than the energy of the reactants but greater than the energy of the products.
|
c.
|
It is greater than the energy of the reactants but less than the energy of the products.
|
d.
|
It is greater than both the energy of the reactants and the energy of the products.
|
____ 51. If a collision between molecules is very gentle, the molecules are —
a.
|
more likely to be oriented favorably
|
b.
|
less likely to be oriented favorably
|
c.
|
likely to react
|
d.
|
likely to rebound without reacting
|
____ 52. Which of the explanations below describes why catalysts can increase reaction rates?
a.
|
Adding a catalyst adds more molecules.
|
b.
|
Adding a catalyst adds heat to the reaction.
|
c.
|
Adding a catalyst adds electricity to the reaction.
|
d.
|
Adding a catalyst provides an alternate reaction mechanism having a lower potential-energy barrier between reactants and products.
|
____ 53. A rate law relates —
a.
|
reaction rate and temperature
|
b.
|
reaction rate and concentration
|
c.
|
temperature and concentration
|
d.
|
energy and concentration
|
____ 54. A certain reaction is zero order in reactant A and second order in reactant B. What happens to the reaction rate when the concentrations of both reactants are doubled?
a.
|
The reaction rate remains the same.
|
b.
|
The reaction rate increases by a factor of two.
|
c.
|
The reaction rate increases by a factor of four.
|
d.
|
The reaction rate increases by a factor of eight.
|
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