Q: A reaction is found to be first order in A and zero order in B. Which of the following rate laws correctly represents this reaction?

$$\text{Rate} = k[\mathrm{A}]$$

Q: A student measures the rate of a reaction and finds that doubling the concentration of reactant X quadruples the rate, while doubling the concentration of reactant Y has no effect. What is the most likely rate law for this reaction?

$$\text{Rate} = k[\mathrm{X}]^2$$

Question 1

According to collision theory, which of the following changes will most likely increase the rate of a chemical reaction between two gases at constant volume?

Accepted Answer

Increasing the temperature of the system

Question 2

A reaction has an activation energy of $$E_a = 50 \ \mathrm{kJ/mol}. If $$the temperature is increased, what happens to the fraction of molecules with enough energy to react?

Accepted Answer

It increases

Question 3

Which of the following best explains why not all collisions between reactant molecules result in a chemical reaction?

Accepted Answer

Only collisions with proper orientation and sufficient energy can overcome the activation energy barrier

Question 4

The rate law for a reaction is given by $$	ext{Rate} = k[\mathrm{A}]^2[\mathrm{B}]. If $$the concentration of A is doubled and B is kept constant, by what factor does the rate increase?

Accepted Answer

4

Question 5

For a first-order reaction, which of the following plots will yield a straight line?

Accepted Answer

$$\ln[\mathrm{A}] vs. $$time

Question 6

A reaction is found to be first order in A and zero order in B. Which of the following rate laws correctly represents this reaction?

Accepted Answer

$$	ext{Rate} = k[\mathrm{A}]$$

Question 7

Which of the following statements about the Maxwell-Boltzmann distribution is correct?

Accepted Answer

At higher temperatures, the distribution broadens and more molecules have enough energy to overcome the activation energy

Question 8

Consider the reaction $$2\mathrm{NO} + \mathrm{O}_2 ightarrow 2\mathrm{NO}_2. If $$the rate law is $$	ext{Rate} = k[\mathrm{NO}]^2[\mathrm{O}_2]$$, what is the overall order of the reaction?

Accepted Answer

Third order

Question 9

A student measures the rate of a reaction and finds that doubling the concentration of reactant X quadruples the rate, while doubling the concentration of reactant Y has no effect. What is the most likely rate law for this reaction?

Accepted Answer

$$	ext{Rate} = k[\mathrm{X}]^2$$

Question 10

Which of the following best describes the effect of a catalyst on a chemical reaction?

Accepted Answer

It decreases the activation energy and increases the rate of reaction

Question 11

For a second-order reaction with the rate law $$	ext{Rate} = k[\mathrm{A}]^2$$, which of the following is the correct integrated rate law?

Accepted Answer

$$\dfrac{1}{[\mathrm{A}]} = kt + \dfrac{1}{[\mathrm{A}]_0}$$

Question 12

In a reaction mechanism, the slowest step is known as the:

Accepted Answer

Rate-determining step

Question 13

If the half-life of a first-order reaction is 10 minutes, what fraction of the reactant remains after 30 minutes?

Accepted Answer

$$\dfrac{1}{8}$$

Question 14

Which of the following changes will NOT affect the rate constant $$k of a $$reaction?

Accepted Answer

Changing the concentration of reactants

Question 15

A reaction has the following rate law: $$	ext{Rate} = k[\mathrm{A}]^1[\mathrm{B}]^0. If $$the concentration of B is tripled, what happens to the rate?

Accepted Answer

It remains the same

Question 16

Which of the following best describes the relationship between temperature and the rate of a chemical reaction?

Accepted Answer

As temperature increases, more molecules have energy greater than the activation energy, so the rate increases

Question 17

In a real-world scenario, why is it important for pharmaceutical companies to understand reaction kinetics when designing drugs?

Accepted Answer

To predict how quickly a drug will degrade or react in the body, affecting dosage and shelf life

Question 18

Which of the following is a correct statement about the units of the rate constant $$k$$ for a second-order reaction?

Accepted Answer

$$\mathrm{M}^{-1}\mathrm{s}^{-1}$$

Question 19

A reaction is found to have the following rate law: $$	ext{Rate} = k[\mathrm{A}]^2[\mathrm{B}]. If $$the initial concentrations are $$[\mathrm{A}] = 0.10\ \mathrm{M}$$ and $$[\mathrm{B}] = 0.20\ \mathrm{M}$$, and the initial rate is $$0.040\ \mathrm{M/s}$$, what will the rate be if $$[\mathrm{A}] is $$doubled and $$[\mathrm{B}] is $$halved?

Accepted Answer

$$0.160\ \mathrm{M/s}$$

Chemical Kinetics: Reaction Rates and Mechanisms

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