Reaction Kinetics: Rates, Factors, and Activation Energy

Question 1

The activation energy of a reaction corresponds to the minimum energy required for:

Accepted Answer

Reactants to transform into products

Answer

Products to revert to reactants

Answer

Catalysts to engage in the reaction

Answer

Inhibitors to impede the reaction

Question 2

The rate constant of a reaction is:

Accepted Answer

Independent of the initial concentration of reactants

Answer

Dependent on the initial concentration of reactants

Answer

Dependent on temperature

Answer

Independent of temperature

Question 3

Which of the following is a type of homogeneous catalyst?

Accepted Answer

Enzymes

Answer

Platinum

Answer

Nickel

Answer

Zeolites

Question 4

Which factor can contribute to a decrease in the rate of a reaction?

Accepted Answer

Decreasing the surface area of reactants

Answer

Increasing the temperature

Answer

Increasing the concentration of reactants

Answer

Adding a catalyst

Question 5

The rate law for a reaction is: rate = k[A][B]². What is the order of the reaction with respect to reactant B?

Accepted Answer

2

Answer

0

Answer

1

Answer

3

Question 6

Which of the following reactions is an example of a homogeneous reaction?

Accepted Answer

Reaction between hydrogen and oxygen

Answer

Reaction between sodium and chlorine

Answer

Reaction between calcium carbonate and hydrochloric acid

Answer

Reaction between copper and silver nitrate

Question 7

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

Accepted Answer

The rate of the reaction is directly proportional to the square of the concentration of the reactant.

Answer

The rate of the reaction is inversely proportional to the concentration of the reactant.

Answer

The half-life of the reaction is independent of the initial concentration of the reactant.

Answer

The reaction is a homogeneous unimolecular process.

Question 8

Which characteristic distinguishes an exothermic reaction?

Accepted Answer

Release of heat

Answer

Absorption of heat

Answer

Lower activation energy than reaction energy

Answer

Spontaneous nature

Question 9

The order of a reaction with respect to a specific reactant refers to:

Accepted Answer

Exponent of the concentration term for that reactant in the rate law

Answer

Slope of the graph of rate against the concentration of that reactant

Answer

Number of molecules of that reactant involved in the reaction

Answer

Activation energy of the reaction

Question 10

The rate law for a reaction can be defined as:

Accepted Answer

Expression showing the dependence of reaction rate on reactant concentrations

Answer

Constant describing the reaction rate

Answer

Graph showing the relationship between reactant concentration and reaction rate

Answer

Table showing reaction rates at different temperatures

Question 11

The SI unit commonly used to express reaction rates is:

Accepted Answer

mol/L/s

Answer

M/s

Answer

L/mol/s

Answer

mol/L

Question 12

Consider the rate law: rate = k[A][B]^2. What is the order of the reaction with respect to reactant B?

Accepted Answer

2

Answer

0

Answer

1

Answer

3

Question 13

What is the half-life of a first-order reaction?

Accepted Answer

t1/2 = ln(2)/k

Answer

t1/2 = k[A]

Answer

t1/2 = [A]/k

Answer

t1/2 = k/ln(2)

Question 14

Which unit is commonly used to express the rate constant of a reaction?

Accepted Answer

M-1s-1

Answer

M/s

Answer

s-1

Answer

s

Question 15

If the rate law for a reaction is rate = k[A]^2[B]^3, what is the overall order of the reaction?

Accepted Answer

5

Answer

1

Answer

2

Answer

3

Question 16

Which factor does NOT directly influence the rate of a chemical reaction?

Accepted Answer

Chemical nature of the reactants

Answer

Concentration of the reactants

Answer

Temperature

Answer

Surface area of the reactants (for heterogeneous reactions)

Question 17

How does the activation energy of a reaction impact its rate?

Accepted Answer

Higher activation energy leads to a slower reaction rate.

Answer

Higher activation energy results in a faster reaction rate.

Answer

Activation energy has no effect on the reaction rate.

Answer

The effect of activation energy on reaction rate varies depending on the reaction.

Question 18

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

Accepted Answer

Size of the container used for the reaction

Answer

Nature of the reactants

Answer

Concentration of the reactants

Answer

Temperature

Question 19

The activation energy of a reaction is the minimum energy that the reactants must possess in order for the reaction to:

Accepted Answer

Commence

Answer

Complete

Answer

Attain equilibrium

Answer

Catalyze

Question 20

A catalyst:

Accepted Answer

Lowers the activation energy of a reaction

Answer

Increases the activation energy of a reaction

Answer

Changes the products of a reaction

Answer

Consumes one of the reactants

Question 21

The half-life of a substance refers to

Accepted Answer

The time it takes for the concentration of a substance to decrease by half

Answer

The time it takes for half of a substance to react

Answer

The time it takes for all of a substance to react

Answer

The time it takes for the activity of a substance to decrease by half

Question 22

Which of the following factors does **not** affect the rate of a chemical reaction?

Accepted Answer

Mass of reactants

Answer

Surface area of reactants

Answer

Temperature

Answer

Concentration of reactants

Question 23

The rate law for a reaction is: rate = k[A]^2[B]. What is the order of the reaction with respect to reactant A?

Accepted Answer

2

Answer

1

Answer

3

Answer

0

Question 24

What is the effect of a catalyst on a reaction?

Accepted Answer

It lowers the activation energy.

Answer

It increases the activation energy.

Answer

It changes the products of the reaction.

Answer

It changes the rate law.

Question 25

What is the half-life of a reaction?

Accepted Answer

The time taken for the concentration of the reactants to decrease by half.

Answer

The time taken for the concentration of the products to increase by half.

Answer

The time taken for the reaction to complete.

Question 26

Which of the following can **not** be used to measure the rate of a reaction?

Accepted Answer

Change in temperature over time

Answer

Change in pressure over time

Answer

Change in concentration over time

Answer

Change in volume over time

Question 27

What is the effect of increasing the temperature of a reaction on the rate of the reaction?

Accepted Answer

The rate of the reaction increases.

Answer

The rate of the reaction decreases.

Answer

The rate of the reaction is unaffected.

Question 28

What is the minimum energy needed for reactants to transform into products called?

Accepted Answer

Activation energy

Answer

Bond energy

Answer

Collision energy

Answer

Reaction energy

Question 29

Define the rate law for a reaction.

Accepted Answer

An equation that links the reaction rate to reactant concentrations

Answer

A graphical representation of reactant concentration changes

Answer

A constant that represents the reaction rate

Question 30

What is reaction order?

Accepted Answer

The sum of the exponents of reactant concentrations in the rate law

Answer

The total number of molecules reacting

Answer

The rate constant for the reaction

Question 31

Describe the rate constant for a reaction.

Accepted Answer

A constant that characterizes the reaction and depends on temperature

Answer

A function that describes changing reactant concentrations over time

Answer

A variable that depends on reactant concentration

Question 32

What is the half-life of a reaction?

Accepted Answer

The time for reactant concentrations to halve

Answer

The time for product concentrations to double

Answer

The rate constant for the reaction

Question 33

Which of the following statements about activation energy is true?

Accepted Answer

It is the minimum energy required for a reaction to occur.

Answer

It is the same for all reactions.

Answer

It is the energy released during a reaction.

Question 34

A catalyst:

Accepted Answer

Increases the rate of a reaction without being consumed

Answer

Is consumed in the reaction

Answer

Decreases the rate of a reaction

Question 35

The half-life of a reaction is the time taken for the concentration of the reactant to:

Accepted Answer

Decrease to half of its initial value

Answer

Decrease by a factor of 10

Answer

Double its initial value

Answer

Increase by a factor of 10

Question 36

If the rate of a reaction doubles when the concentration of reactant A is tripled, what is the order of the reaction with respect to reactant A?

Accepted Answer

2

Answer

4

Answer

1

Answer

3

Question 37

Which of the following is the primary role of a catalyst in a chemical reaction?

Accepted Answer

Lowering the activation energy

Answer

Increasing the selectivity of the reaction

Answer

Increasing the concentration of reactants

Answer

Changing the nature of the reaction

Question 38

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

Accepted Answer

Volume of the container

Answer

Temperature

Answer

Concentration of reactants

Answer

Nature of the catalyst

Question 39

Define the activation energy of a reaction.

Accepted Answer

The minimum amount of energy that reactants must possess to form the transition state.

Answer

The energy required to break bonds in reactants.

Answer

The energy required to overcome the repulsion between reactants.

Answer

The energy released when products are formed.

Question 40

What is the primary function of a catalyst in a chemical reaction?

Accepted Answer

To lower the activation energy of the reaction.

Answer

To consume reactants in the reaction.

Answer

To change the products of the reaction.

Answer

To increase the concentration of reactants.

Question 41

How is the rate law for a reaction experimentally determined?

Accepted Answer

By measuring the change in concentration of reactants or products over time.

Answer

By using spectroscopy to analyze the reaction.

Answer

By calculating the number of moles of reactants and products.

Answer

By predicting the rate based on the activation energy.

Question 42

Identify the integrated rate law for a first-order reaction.

Accepted Answer

ln[A] = -kt + ln[A]0.

Answer

A = A0ekt.

Answer

[A] = k[B][C].

Answer

A = k[B].

Question 43

Define the half-life of a reaction.

Accepted Answer

The time required for the concentration of a reactant to decrease by half.

Answer

The time required for the reaction to reach completion.

Answer

The time required for the concentration of a product to increase by half.

Question 44

Which method is commonly used to determine the order of a reaction?

Accepted Answer

Method of initial rates.

Answer

Method of integration.

Answer

Method of spectroscopy.

Answer

Method of half-life.

Question 45

State the relationship described by the Arrhenius equation.

Accepted Answer

The relationship between the rate constant of a reaction, temperature, and activation energy.

Answer

The relationship between the equilibrium constant and temperature.

Answer

The relationship between the concentration of reactants and the rate of reaction.

Question 46

Identify the key characteristic of enzyme catalysis.

Accepted Answer

Enzymes lower the activation energy of reactions.

Answer

Enzymes increase the activation energy of reactions.

Answer

Enzymes are consumed in reactions.

Answer

Enzymes are only effective at high temperatures.

Question 47

Describe the significance of the Michaelis-Menten equation.

Accepted Answer

It describes the relationship between the reaction rate and substrate concentration for enzyme-catalyzed reactions.

Answer

It predicts the products of enzyme-catalyzed reactions.

Question 48

Which of the following factors does NOT affect the rate of a chemical reaction?

Accepted Answer

Temperature of the Moon

Answer

Presence of a catalyst

Answer

Concentration of reactants

Answer

Surface area of reactants

Question 49

A catalyst speeds up a reaction by:

Accepted Answer

Providing an alternative pathway with a lower activation energy

Answer

Decreasing the temperature

Answer

Changing the products of the reaction

Answer

Increasing the concentration of reactants

Question 50

The following mechanism is proposed for a reaction:
A + B <=> C
C + D -> E
Which of the following is the intermediate in the reaction?

Accepted Answer

C

Answer

A

Answer

B

Answer

D

Question 51

Which of the following is a heterogeneous catalyst?

Accepted Answer

Fe2O3

Answer

Pt

Answer

H+

Answer

Ni