Question 1

Which of the following changes will increase the rate of a chemical reaction according to collision theory?

Accepted Answer

Adding a catalyst

Question 2

For the reaction $$2N_2O \rightarrow 2N_2 + O_2$, if the rate of disappearance of N_2O$ is 0.10$$\ \mathrm{mol\ $$L^{-1}$$\ $$s^{-1}$$}$$, what is the rate of appearance of O_2$?

Accepted Answer

$$0.05\ \mathrm{mol\ L$$^{-1}$$\ s$$^{-1}$$}$$

Question 3

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

Accepted Answer

18

Question 4

Which of the following best describes the role of a catalyst in a chemical reaction?

Accepted Answer

It provides an alternative reaction pathway with a lower activation energy.

Question 5

Given the reaction $$A ightarrow P$$ with a rate law $$	ext{rate} = k[A]$$, what is the order of the reaction with respect to $$A$$?

Accepted Answer

First-order

Question 6

A student measures the concentration of a reactant $$A$$ over time and finds that a plot of $$\ln[A]$$ versus time is linear. What is the most likely rate law for the reaction?

Accepted Answer

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

Question 7

For the reaction $$2A + B \rightarrow 3C$$, the rate of disappearance of $$A is$$ $$0.20\ \mathrm{M/s}. $$What is the rate of formation of $$C$$?

Accepted Answer

$$0.30\ \mathrm{M/s}$$

Question 8

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

Accepted Answer

It increases as temperature increases.

Question 9

A reaction is found to be zero-order in $$A. If $$the initial concentration of $$A is$$ $$0.50\ \mathrm{M}$$ and the rate constant $$k is$$ $$0.10\ \mathrm{M/s}$$, how long will it take for $$[A] to $$reach $$0.10\ \mathrm{M}$$?

Accepted Answer

$$4.0\ \mathrm{s}$$

Question 10

The rate law for a reaction is determined to be $$	ext{rate} = k[NO_2$]^2. $$Which of the following mechanisms is consistent with this rate law?

Accepted Answer

A single-step mechanism involving two $$NO_2$$ molecules colliding

Question 11

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

Accepted Answer

It increases the number of collisions with sufficient energy to overcome the activation barrier.

Question 12

For a first-order reaction, which of the following is true about the half-life?

Accepted Answer

It is constant and independent of concentration.

Question 13

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

Accepted Answer

$$k$$ decreases

Question 14

A reaction has a rate law $$	ext{rate} = k[A]^2. If $$the initial concentration of $$A is$$ $$0.80\ \mathrm{M}$$ and the rate constant $$k is$$ $$0.50\ \mathrm{M$$^{-1}$$s^{-1}$$}$, what is the initial rate?

Accepted Answer

$$0.16\ \mathrm{M/s}$$

Question 15

Which of the following is NOT a factor that affects the rate of a chemical reaction?

Accepted Answer

The color of the reactants

Question 16

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

Accepted Answer

The slowest (rate-determining) step

Question 17

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

Accepted Answer

A species formed in one step and consumed in a later step

Question 18

For a reaction with the integrated rate law $$[A] = [A]_0 - kt$$, which of the following is true?

Accepted Answer

The reaction is zero-order in $$A$$

Question 19

Which of the following statements about enzymes is correct?

Accepted Answer

They lower the activation energy of biological reactions.

Question 20

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

Accepted Answer

It remains the same as the original rate

Chemical Kinetics: Introduction and Fundamental Concepts

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