Question 1

Which of the following best describes the rate law for a reaction where the rate is directly proportional to the concentration of a single reactant A?

Accepted Answer

$$	ext{rate} = k 	imes [A]$$

Question 2

A reaction has the rate law $$	ext{rate} = k[A]^2. If $$the concentration of A is doubled, what happens to the rate of the reaction?

Accepted Answer

The rate is quadrupled.

Question 3

In a reaction mechanism, what is an intermediate?

Accepted Answer

A species produced in one step and consumed in the next step.

Question 4

For the reaction $$aA + bB ightarrow cC + dD$$ with the rate law $$	ext{rate} = k[A]^x[B]^y$$, what is the overall order of the reaction?

Accepted Answer

$$x + y$$

Question 5

A reaction is first order in A and first order in B. If both [A] and [B] are doubled, by what factor does the rate increase?

Accepted Answer

4

Question 6

Which of the following statements about the specific rate constant $$k is $$correct?

Accepted Answer

$$k is $$larger for faster reactions.

Question 7

Given the following data for a reaction $$A ightarrow B$$:
Trial 1: $$[A] = 0.050$$ mol/L, Rate = $$3.0 	imes 10$$^{-4}$$ mol/(L·s)
Trial 2: $$[A] = 0.10$$ mol/L, Rate = 12$$ 	imes $$10^{-4}$$ mol/(L·s)
What is the order of the reaction with respect to A?

Accepted Answer

Second order

Question 8

In a multistep reaction, which step determines the overall rate of the reaction?

Accepted Answer

The slowest step

Question 9

Which of the following best describes an elementary reaction?

Accepted Answer

A reaction that occurs in a single step with one activation energy peak.

Question 10

A reaction has the rate law $$	ext{rate} = k[A][B]. If$$ $$[A] is $$tripled and $$[B] is $$kept constant, how does the rate change?

Accepted Answer

It is tripled.

Question 11

Which of the following is NOT true about reaction intermediates?

Accepted Answer

They appear in the overall balanced equation.

Question 12

In the decomposition of nitrous oxide ($$2N_2O \rightarrow 2N_2 + O_2$), the first step is the rate-determining step. What would increase the overall reaction rate?

Accepted Answer

Increasing the rate of the first step

Question 13

A reaction has the rate law $$	ext{rate} = k[A]^2. If $$the initial concentration of A is 2.0 mol/L and the initial rate is $$9.6 	imes 10$$^{-7}$$ mol/(L·s), what is the concentration of A when the rate is 1.2$$ 	imes $$10^{-7}$$ mol/(L·s)?

Accepted Answer

0.71 mol/L

Question 14

Which of the following best describes the energy profile of a multistep reaction?

Accepted Answer

It has multiple peaks and valleys, each peak representing an activated complex and each valley an intermediate.

Question 15

If a reaction is zero order in A, how does changing the concentration of A affect the rate?

Accepted Answer

The rate remains unchanged.

Question 16

Which of the following is a correct definition of a rate law?

Accepted Answer

An expression relating the rate of a reaction to the concentration of the reactants.

Question 17

In a real-world scenario, why might a pharmaceutical company be interested in the rate-determining step of a drug synthesis reaction?

Accepted Answer

To increase the overall yield by speeding up the slowest step.

Question 18

Which of the following is true about the order of a reaction?

Accepted Answer

It must be determined experimentally.

Question 19

A reaction has the rate law $$	ext{rate} = k[A]^x[B]^y. If $$the rate doubles when [A] is doubled and [B] is held constant, what is the value of x?

Accepted Answer

1

Question 20

Which of the following best describes the role of an intermediate in a reaction mechanism?

Accepted Answer

It is a product in one step and a reactant in the next step.

Reaction Rates and Mechanisms: The Progress of Chemical Reactions

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