Reaction Rates: Interactive Quizzes and Practice Questions

Question 1

A catalyst in a chemical reaction:

Accepted Answer

Decreases the activation energy of the reaction

Answer

Increases the activation energy of the reaction

Answer

Changes the products of the reaction

Answer

Is consumed during the reaction

Question 2

Identify the rate-limiting step in a reaction:

Accepted Answer

The slowest step in a multi-step reaction mechanism

Answer

The first step in a reaction mechanism

Answer

The last step in a reaction mechanism

Answer

The step that produces the final product

Question 3

A characteristic of a zero-order reaction is that the:

Accepted Answer

Rate is independent of the concentration of reactants

Answer

Rate is proportional to the concentration of reactants

Answer

Rate increases exponentially with time

Answer

Half-life is constant

Question 4

The rate constant for a reaction is:

Accepted Answer

The proportionality constant in the rate law

Answer

The initial concentration of reactants

Answer

The activation energy of the reaction

Answer

Independent of temperature

Question 5

The rate law for a reaction is an expression that:

Accepted Answer

Relates the rate of the reaction to the concentrations of reactants

Answer

Describes the equilibrium constant of the reaction

Answer

Predicts the products of the reaction

Answer

Determines the activation energy of the reaction

Question 6

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

0

Answer

1

Answer

3

Question 7

The activation energy of a reaction is the minimum amount of energy that reactants must have to react. Which of the following will decrease the activation energy of a reaction?

Accepted Answer

Adding a catalyst

Answer

Decreasing the temperature

Answer

Increasing the concentration of products

Answer

Decreasing the surface area of the reactants

Question 8

The rate constant for a reaction is 2.5 x 10^-3 s^-1. What is the rate of the reaction when the concentration of the reactant is 0.25 M?

Accepted Answer

6.25 x 10^-4 M s^-1

Answer

1.25 x 10^-3 M s^-1

Answer

2.5 x 10^-3 M s^-1

Answer

5.0 x 10^-3 M s^-1

Question 9

Which of the following experimental techniques can be used to determine the order of a reaction and the rate constant?

Accepted Answer

Spectrophotometry

Answer

Titration

Answer

Gas chromatography

Answer

X-ray diffraction

Question 10

Which of the following factors does not affect the reaction rate?

Accepted Answer

Volume of the reaction vessel

Answer

Concentration of reactants

Answer

Temperature

Answer

Presence of a catalyst

Question 11

The order of a reaction with respect to a specific reactant is determined by:

Accepted Answer

The exponent to which the concentration of the reactant is raised in the rate law expression

Answer

The stoichiometric coefficient of the reactant in the balanced chemical equation

Answer

The change in concentration of the reactant over time

Answer

The initial concentration of the reactant

Question 12

Which characteristic is unique to a catalyst?

Accepted Answer

It lowers the activation energy of the reaction.

Answer

It is consumed in the reaction.

Answer

It increases the activation energy of the reaction.

Answer

It changes the products of the reaction.

Question 13

The Arrhenius equation establishes the relationship between which factors?

Accepted Answer

Rate constant and temperature

Answer

Reaction rate and temperature

Answer

Activation energy and temperature

Answer

Activation energy and rate constant

Question 14

Which experimental methods can be utilized to determine the order of a reaction?

Accepted Answer

Any of the above

Answer

Initial rate method

Answer

Integrated rate method

Answer

Graphical method

Question 15

The activation energy of a reaction is a measure of:

Accepted Answer

The minimum energy required for the reaction to proceed

Answer

The energy difference between reactants and products

Answer

The rate of the reaction

Answer

The temperature at which the reaction occurs

Question 16

For a reaction with two reactants, A and B, the rate law expression is given as: rate = k[A]^m[B]^n. What is the overall order of the reaction?

Accepted Answer

m + n

Answer

m

Answer

n

Answer

Cannot be determined from the provided information

Question 17

A reaction is determined to be first-order with respect to both reactant 'A' and 'B'. Which of the following rate laws accurately represents the reaction?

Accepted Answer

Rate = k[A][B]

Answer

Rate = k[A]^2[B]

Answer

Rate = k[A][B]^2

Answer

Rate = k[A]^2[B]^2

Question 18

How does a catalyst enhance the rate of a reaction?

Accepted Answer

Both B and C

Answer

Increases the energy of the reactants

Answer

Provides an alternative reaction pathway

Answer

Decreases the activation energy

Question 19

The rate of a reaction doubles when the concentration of one of the reactants is tripled. What is the order of the reaction with respect to this reactant?

Accepted Answer

Second order

Answer

First order

Answer

Third order

Answer

Unable to determine from the provided information

Question 20

A catalyst speeds up a reaction by:

Accepted Answer

Decreasing the activation energy of the reaction

Answer

Increasing the activation energy of the reaction

Answer

Changing the equilibrium constant of the reaction

Answer

Altering the concentration of the products

Question 21

Which of the following units represents activation energy?

Accepted Answer

Joules per mole

Answer

Degrees Celsius

Answer

Moles per liter

Answer

Kelvin

Question 22

The rate constant for a reaction is 2.5 x 10^-3 s^-1 at 25 °C. Calculate the half-life of the reaction.

Accepted Answer

0.277 s

Answer

10.3 s

Answer

277 s

Answer

1030 s

Question 23

Which of the following is not a method to increase the rate of a reaction?

Accepted Answer

Diluting the reaction mixture

Answer

Increasing the temperature

Answer

Adding a catalyst

Answer

Increasing the surface area of the reactants

Question 24

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

Accepted Answer

48 kJ/mol

Answer

24 kJ/mol

Answer

72 kJ/mol

Answer

96 kJ/mol

Question 25

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

Accepted Answer

Pressure

Answer

Temperature

Answer

Surface area of reactants

Answer

Concentration

Question 26

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

4

Answer

6

Answer

2

Question 27

A reaction has an activation energy of 80 kJ/mol. The rate constant at 30 °C is 2.0 x 10^-4 M^-1 s^-1. What is the rate constant at 40 °C, assuming the Arrhenius equation is valid?

Accepted Answer

5.4 x 10^-3 M^-1 s^-1

Answer

1.4 x 10^-2 M^-1 s^-1

Answer

1.1 x 10^-4 M^-1 s^-1

Question 28

Which of the following is the best catalyst for the hydrogenation of an alkene?

Accepted Answer

Palladium

Answer

Iron

Answer

Copper

Answer

Zinc

Question 29

The rate of a reaction quadruples for every 10 °C increase in temperature. What is the temperature coefficient (Q10) for this reaction?

Accepted Answer

4

Answer

2

Answer

1.5

Answer

2.5

Question 30

Which of the following reactions is a unimolecular reaction?

Accepted Answer

CH3Br(g) -> CH3(g) + Br(g)

Answer

NO2(g) -> NO(g) + O(g)

Answer

H2O2(aq) -> H2O(l) + O2(g)

Answer

N2O5(g) -> 2NO2(g)

Question 31

The half-life of a reaction is 20 minutes. What is the rate constant for this reaction?

Accepted Answer

0.0347 min^-1

Answer

0.00347 min^-1

Answer

0.01 min^-1

Answer

0.1 min^-1

Question 32

Which of the following is a heterogeneous catalyst?

Accepted Answer

Zeolite

Answer

Nickel

Answer

Sulfuric acid

Answer

Platinum

Question 33

The following mechanism is proposed for a reaction: A + B -> C, C + B -> D + E. What is the molecularity of the overall reaction?

Accepted Answer

Termolecular

Answer

Quadrimolecular

Answer

Unimolecular

Answer

Bimolecular

Question 34

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

Accepted Answer

Light intensity

Answer

Concentration

Answer

Surface area

Answer

Temperature

Question 35

The rate constant for a reaction is doubled when the temperature is increased from 25 °C to 35 °C. Calculate the activation energy for the reaction.

Accepted Answer

52.4 kJ/mol

Answer

78.6 kJ/mol

Answer

26.2 kJ/mol

Answer

104.8 kJ/mol

Question 36

A reaction is first order with respect to reactant A and second order with respect to reactant B. What is the overall order of the reaction?

Accepted Answer

3

Answer

1

Answer

4

Answer

2

Question 37

Which of the following is NOT a type of catalyst?

Accepted Answer

Inhibitor

Answer

Heterogeneous

Answer

Homogeneous

Answer

Enzymes

Question 38

A reaction has a half-life of 10 minutes. How long will it take for the concentration of the reactant to decrease to 1/8 of its initial value?

Accepted Answer

30 minutes

Answer

20 minutes

Answer

50 minutes

Answer

40 minutes

Question 39

Which of the following is the correct rate law expression for a reaction that is first order with respect to A and zero order with respect to B?

Accepted Answer

Rate = k[A]

Answer

Rate = k[A]/[B]

Answer

Rate = k[A]^2

Answer

Rate = k[A][B]

Question 40

A reaction is exothermic. Which of the following will increase the rate of the reaction?

Accepted Answer

Adding heat

Answer

Adding a catalyst

Answer

Increasing the volume of the reaction vessel

Answer

Decreasing the temperature

Question 41

Which of the following is a characteristic of a unimolecular reaction?

Accepted Answer

It involves the decomposition of a single reactant molecule.

Answer

It has a high activation energy.

Answer

It is always bimolecular

Question 42

A catalyst lowers the activation energy of a reaction by:

Accepted Answer

Providing an alternative reaction pathway with a lower energy barrier.

Answer

Increasing the concentration of reactants.

Answer

Increasing the temperature of the reaction.

Question 43

The rate of a reaction doubles when the concentration of the reactant is tripled. What is the order of the reaction?

Accepted Answer

2

Answer

1

Answer

4

Answer

3