Question 1

According to collision theory, which of the following is NOT a requirement for a successful chemical reaction between two molecules?

Accepted Answer

The molecules must collide with a catalyst present.

Question 2

Which of the following best explains why increasing the temperature generally increases the rate of a chemical reaction?

Accepted Answer

It increases the fraction of molecules with kinetic energy greater than the activation energy.

Question 3

Given the reaction: $$2NO(g) + Br_2$(g) ightarrow 2NOBr(g)$$, and the experimentally determined rate law $$	ext{Rate} = k[NO]^3$$, what is the order of the reaction with respect to $$Br_2$$?

Accepted Answer

Zero order

Question 4

A catalyst increases the rate of a chemical reaction by:

Accepted Answer

Decreasing the activation energy required for the reaction.

Question 5

Which of the following statements about the rate-determining step in a multi-step reaction mechanism is correct?

Accepted Answer

It has the highest activation energy and limits the overall reaction rate.

Question 6

For the reaction $$H_2O_2 + 3I^- + 2H^+ ightarrow I_3$^- + 2H_2O$$ with the rate law $$	ext{Rate} = k[H_2O_2]^2[I^-]^0[H^+]^1$$, what is the overall order of the reaction?

Accepted Answer

Third order

Question 7

Which of the following graphs best represents the effect of a catalyst on the activation energy of a reaction?

Accepted Answer

A reaction progress diagram where the catalyzed pathway has a lower peak than the uncatalyzed pathway.

Question 8

The Arrhenius equation is $$k = Ae$$^{-E_a/RT}$$. If the activation energy (E_a$) increases while all other factors remain constant, what happens to the rate constant (k$)?

Accepted Answer

It decreases.

Question 9

In a reaction mechanism, which species is NOT included in the experimentally determined rate law?

Accepted Answer

Intermediates formed and consumed during the mechanism.

Question 10

A student increases the concentration of a reactant in a reaction and observes that the rate does not change. What is the most likely order of the reaction with respect to this reactant?

Accepted Answer

Zero order

Question 11

Which of the following best describes the effect of increasing the surface area of a solid reactant on the rate of a heterogeneous reaction?

Accepted Answer

It increases the frequency of effective collisions.

Question 12

Given the Arrhenius equation $$k = Ae$$^{-E_a/RT}$$, which of the following changes will result in the greatest increase in the rate constant k$?

Accepted Answer

Increasing the temperature.

Question 13

Which of the following is a correct statement about enzymes?

Accepted Answer

They are biological catalysts that increase the rate of biochemical reactions.

Question 14

A reaction has a rate law $$	ext{Rate} = k[A]^2[B]^1. If $$the concentration of $$A is $$doubled and $$B is $$tripled, by what factor does the rate increase?

Accepted Answer

12

Question 15

Which of the following best explains why termolecular elementary steps are rare?

Accepted Answer

They require three molecules to collide simultaneously with the correct orientation and sufficient energy, which is statistically unlikely.

Question 16

In the context of reaction mechanisms, what is a reactive intermediate?

Accepted Answer

A species that is formed in one step and consumed in a subsequent step of the mechanism.

Question 17

If a reaction is first order in $$A$$ and zero order in $$B$$, which of the following rate laws is correct?

Accepted Answer

$$	ext{Rate} = k[A]^1[B]^0$$

Question 18

Which of the following statements about the units of the rate constant $$k is $$true for a third-order reaction?

Accepted Answer

$$M^{-2}$$ $$s^{-1}$$

Question 19

A plot of $$\ln k$$ versus $$1/T$$ for a reaction yields a straight line with a negative slope. What does the magnitude of the slope represent?

Accepted Answer

$$E_a/R$$

Question 20

Which of the following changes will NOT affect the rate of a reaction according to the rate law $$	ext{Rate} = k[A]^2$$?

Accepted Answer

Increasing the concentration of a reactant not in the rate law

Chemical Kinetics: Rates, Mechanisms, and Factors Affecting Reactions

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