Question 1

Which of the following statements best explains why powdered calcium carbonate reacts faster with hydrochloric acid than a solid block of calcium carbonate under identical conditions?

Accepted Answer

Powdered calcium carbonate has a greater surface area, allowing more frequent collisions with hydrochloric acid molecules.

Question 2

A reaction is found to be first order in A and second order in B. What is the correct rate law for this reaction?

Accepted Answer

$$ 	ext{rate} = k[A][B]^2 $$

Question 3

Which of the following changes will NOT increase the rate of a chemical reaction?

Accepted Answer

Decreasing the concentration of reactants.

Question 4

The half-life of a first-order reaction is given by which of the following equations?

Accepted Answer

$$ t_{1/2} = \frac{0.693}{k} $$

Question 5

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

Accepted Answer

It lowers the activation energy, providing an alternative pathway for the reaction.

Question 6

For the reaction $$ 2NO_2 ightarrow 2NO + O_2$ $$, the rate law is found to be $$ 	ext{rate} = k[NO_2$]^2 . $$What is the order of the reaction?

Accepted Answer

Second order

Question 7

Which of the following is true about the rate-determining step in a reaction mechanism?

Accepted Answer

It is the slowest step in the mechanism and determines the overall reaction rate.

Question 8

The Arrhenius equation relates the rate constant $$ k  to $$temperature $$ T $$ and activation energy $$ E_a . $$Which is the correct form of the Arrhenius equation?

Accepted Answer

$$ k = A e$$^{-E_a/(RT)}$$ $$

Question 9

Which of the following statements about reaction intermediates is correct?

Accepted Answer

Intermediates are produced in one step and consumed in a subsequent step of the mechanism.

Question 10

A reaction has a rate law $$ 	ext{rate} = k . $$What is the order of this reaction?

Accepted Answer

Zero order

Question 11

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

Accepted Answer

More molecules have sufficient energy to overcome the activation energy barrier.

Question 12

Which of the following is a characteristic of a second-order reaction?

Accepted Answer

A plot of $$ 1/[A] $$ versus time is linear.

Question 13

In a biological system, an enzyme acts as a catalyst. Which statement best describes how enzymes function?

Accepted Answer

Enzymes provide an alternative reaction pathway with a lower activation energy.

Question 14

Which of the following is NOT a requirement for a plausible reaction mechanism?

Accepted Answer

The mechanism must have only one step.

Question 15

A chemist observes that doubling the concentration of reactant X quadruples the reaction rate. What is the order of the reaction with respect to X?

Accepted Answer

Second order

Question 16

Which of the following best describes a termolecular elementary step?

Accepted Answer

It involves the simultaneous collision of three molecules and is rare.

Question 17

Which of the following is true about the effect of a catalyst on a reaction?

Accepted Answer

It provides a new mechanism with a lower activation energy.

Question 18

For a reaction with the rate law $$ 	ext{rate} = k[A]^0 $$, which of the following statements is correct?

Accepted Answer

The rate is independent of the concentration of A.

Question 19

Which of the following is a correct statement about the transition state (activated complex) in a chemical reaction?

Accepted Answer

It is the highest energy arrangement of atoms along the reaction pathway.

Question 20

A reaction is found to have a rate constant $$ k $$ that doubles when the temperature is increased by $$ 10 ^\circ C . $$This observation is best explained by which concept?

Accepted Answer

The Arrhenius equation, which shows that $$ k $$ increases exponentially with temperature.

Chapter 14: Chemical Kinetics – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards