Chemical Reaction Rates: Interactive Quizzes and Practice Questions

Question 1

What is the unit of activation energy?

Accepted Answer

kJ mol^-1

Answer

J mol^-1

Answer

kcal mol^-1

Answer

J

Question 2

Define the order of a reaction with respect to a particular reactant.

Accepted Answer

The power to which the concentration of that reactant is raised in the rate law

Answer

The number of moles of that reactant consumed in the reaction

Answer

The rate at which that reactant is consumed in the reaction

Answer

The activation energy of the reaction

Question 3

Define the half-life of a reaction.

Accepted Answer

The time it takes for the concentration of the reactant to decrease by 50%

Answer

The time it takes for the concentration of the reactant to decrease by 25%

Answer

The time it takes for the concentration of the reactant to decrease by 75%

Answer

The time it takes for the concentration of the reactant to decrease by 100%

Question 4

Which factor does NOT affect the rate of a chemical reaction?

Accepted Answer

Type of reaction vessel used

Answer

Concentration of reactants

Answer

Temperature

Answer

Presence of a catalyst

Question 5

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

Accepted Answer

The slowest step

Answer

The first step

Answer

The last step

Answer

The step with the lowest activation energy

Question 6

What is the impact of increasing the temperature of a reaction on its rate?

Accepted Answer

Increases the rate

Answer

Decreases the rate

Answer

No effect on the rate

Answer

Can increase or decrease the rate depending on the reaction

Question 7

Which of the following substances can act as a catalyst in chemical reactions?

Accepted Answer

Platinum

Answer

Sodium chloride

Answer

Hydrochloric acid

Answer

Water

Question 8

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

Accepted Answer

Concentration of the reactants

Answer

Nature of the reactants

Answer

Temperature

Answer

Presence of a catalyst

Question 9

The rate law for a reaction expresses the:

Accepted Answer

Relationship between the rate of the reaction and the concentrations of the reactants

Answer

Activation energy of the reaction

Answer

Equilibrium constant of the reaction

Answer

Enthalpy change of the reaction

Question 10

A reaction that is zero order with respect to a reactant means that:

Accepted Answer

The rate of the reaction is independent of the concentration of that reactant

Answer

The rate of the reaction is directly proportional to the concentration of that reactant

Answer

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

Answer

The rate of the reaction is second order with respect to that reactant

Question 11

Activation energy is defined as the

Accepted Answer

Minimum energy required for a reaction to occur

Answer

Energy released during the reaction

Answer

Energy absorbed during the reaction

Answer

Energy possessed by the products

Question 12

The rate law for a chemical reaction is an equation that relates the

Accepted Answer

Rate of the reaction to the concentrations of the reactants

Answer

Rate of the reaction to the activation energy

Answer

Activation energy to the concentrations of the reactants

Answer

Rate of the reaction to the temperature

Question 13

The half-life of a reaction is the time required for

Accepted Answer

The concentration of the reactants to decrease by half

Answer

The concentration of the products to double

Answer

The rate of the reaction to halve

Answer

The equilibrium constant to be reached

Question 14

Which of the following is NOT a method used to determine the rate law of a reaction?

Accepted Answer

Equilibrium method

Answer

Initial rate method

Answer

Integrated rate method

Answer

Half-life method

Question 15

Which of the following is a consequence of increasing the temperature of a reaction?

Accepted Answer

Increased collision frequency and energy.

Answer

Lowered activation energy.

Answer

Reduced rate of reaction.

Answer

Decreased number of collisions with sufficient energy.

Question 16

The activation energy of a reaction is the minimum amount of energy required to:

Accepted Answer

Form an activated complex

Answer

Break reactant bonds

Answer

Release product molecules

Answer

Increase the rate of the reaction

Question 17

Which of the following is a catalyst?

Accepted Answer

A substance that speeds up a reaction without being consumed

Answer

A substance that is produced in a reaction

Answer

A substance that slows down a reaction

Question 18

The rate law for a reaction is:

Accepted Answer

An equation that shows the relationship between the rate of the reaction and the concentrations of the reactants

Answer

An equation that shows the products of the reaction

Question 19

The half-life of a reaction is the time it takes for:

Accepted Answer

Half of the reactants to be consumed

Answer

Half of the products to be formed

Answer

All of the products to be formed

Answer

All of the reactants to be consumed

Question 20

The equilibrium constant for a reaction is:

Accepted Answer

A number that indicates the relative amounts of reactants and products at equilibrium

Answer

A number that indicates the rate of the reaction

Answer

A number that indicates the activation energy of the reaction

Question 21

Which of the following is a characteristic of a reaction that is at equilibrium?

Accepted Answer

The forward and reverse reactions are occurring at the same rate

Answer

The concentration of reactants is increasing

Answer

The concentration of products is decreasing

Question 22

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

Accepted Answer

A reaction in which all the reactants and products are in the same phase

Answer

A reaction in which the reactants and products are in different phases

Answer

A reaction that is catalyzed by a solid

Question 23

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

Accepted Answer

The temperature of the surroundings

Answer

The concentration of the reactants

Answer

The presence of a catalyst

Answer

The phase of the reactants

Question 24

The rate constant for a reaction is 2.5 x 10^-3 mol dm^-3 s^-1. What is the rate of the reaction when the concentration of the reactant is 0.1 mol dm^-3?

Accepted Answer

2.5 x 10^-4 mol dm^-3 s^-1

Answer

2.5 x 10^-2 mol dm^-3 s^-1

Answer

2.5 x 10^-5 mol dm^-3 s^-1

Answer

2.5 x 10^-6 mol dm^-3 s^-1

Question 25

Which of the following is the unit of activation energy?

Accepted Answer

kJ mol^-1

Answer

K

Answer

s^-1

Answer

mol dm^-3

Question 26

The activation energy of a reaction is 50 kJ mol^-1. What is the effect of increasing the temperature by 20 K on the rate of the reaction?

Accepted Answer

The rate of the reaction will double.

Answer

The rate of the reaction will increase by a factor of 4.

Answer

The rate of the reaction will not change.

Answer

The rate of the reaction will increase by a factor of 8.

Question 27

A catalyst is a substance that:

Accepted Answer

Increases the rate of a reaction without being consumed

Answer

Decreases the rate of a reaction without being consumed

Answer

Increases the rate of a reaction and is consumed

Question 28

Which of the following is NOT a type of catalyst?

Accepted Answer

Homogeneous catalyst

Answer

Enzyme catalyst

Answer

Autocatalyst

Answer

Heterogeneous catalyst

Question 29

The rate of a reaction is doubled when the temperature is increased from 25 °C to 35 °C. What is the activation energy of the reaction?

Accepted Answer

51 kJ mol^-1

Answer

25 kJ mol^-1

Answer

102 kJ mol^-1

Answer

204 kJ mol^-1

Question 30

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

Accepted Answer

The slowest step

Answer

The last step

Answer

The fastest step

Answer

The first step

Question 31

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

Accepted Answer

The rate of the reaction is independent of the concentration of the reactants

Answer

The rate of the reaction is proportional to the square of the concentration of one of the reactants

Answer

The rate of the reaction is proportional to the concentration of one of the reactants