Energetics and Kinetics: Master Chemical Energy and Reaction Rates

Question 1

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

Accepted Answer

Color of the reaction mixture

Answer

Temperature

Answer

Concentration of reactants

Answer

Presence of a catalyst

Question 2

How do enthalpy changes relate to bond enthalpies?

Accepted Answer

Enthalpy changes are directly proportional to the difference in bond enthalpies of reactants and products.

Answer

Enthalpy changes are inversely proportional to the sum of bond enthalpies of reactants and products.

Answer

Enthalpy changes are independent of bond enthalpies.

Answer

Enthalpy changes are equal to the bond enthalpy of the strongest bond in the products.

Question 3

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

Accepted Answer

Size of the reaction vessel

Answer

Temperature

Answer

Concentration of reactants

Answer

Presence of a catalyst

Question 4

When methane gas burns, heat is released. Based on this observation, is the enthalpy change of the combustion reaction positive (endothermic), negative (exothermic), or zero?

Accepted Answer

Negative (Exothermic)

Answer

Positive (Endothermic)

Answer

Zero

Question 5

Thermodynamic spontaneity is determined solely by

Accepted Answer

Gibbs free energy

Answer

Enthalpy

Answer

Entropy

Answer

Reaction rate

Question 6

Which of the following options correctly defines the enthalpy of formation of a compound?

Accepted Answer

The heat released when one mole of a compound is formed from its constituent elements in their standard states.

Answer

The heat absorbed when one mole of a compound is decomposed into its constituent elements.

Answer

The difference in enthalpy between a compound and its constituent elements.

Answer

The heat released when one gram of a compound is formed.

Question 7

In a chemical reaction, enthalpy change refers to:

Accepted Answer

The difference in enthalpy between the reactants and products

Answer

The change in activation energy

Answer

The heat energy absorbed by the surroundings

Answer

The maximum amount of work that can be done by the system

Question 8

What is the definition of activation energy in a chemical reaction?

Accepted Answer

The minimum energy required for a reaction to occur

Answer

The energy difference between reactants and products

Answer

The energy dependent only on the reactants

Answer

The energy that increases the reaction rate

Question 9

Which factor does NOT directly affect the speed of a chemical reaction?

Accepted Answer

Volume of the reaction vessel

Answer

Temperature

Answer

Concentration of reactants

Answer

Nature of the catalyst

Question 10

Which of the following processes is spontaneous, meaning it occurs without the need for external energy input?

Accepted Answer

A process with a negative Gibbs free energy change

Answer

A process with a positive Gibbs free energy change

Answer

A process with a zero Gibbs free energy change

Answer

A process that requires the addition of heat to occur

Question 11

What does a negative Gibbs free energy change (ΔG) indicate?

Accepted Answer

B. A spontaneous reaction

Answer

A. A nonspontaneous reaction

Answer

C. An equilibrium reaction

Answer

D. A reaction that requires a catalyst

Question 12

The combustion of methane gas (CH₄) releases energy. What is the sign of the Gibbs free energy change (ΔG) for this reaction?

Accepted Answer

Negative, indicating a spontaneous reaction.

Answer

Positive, indicating a nonspontaneous reaction.

Answer

Zero, indicating a reaction at equilibrium.

Answer

The sign of ΔG cannot be determined from the given information.

Question 13

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

Accepted Answer

Concentration of products

Answer

Temperature

Answer

Surface area of reactants

Question 14

How do catalysts enable chemical reactions to occur without being consumed?

Accepted Answer

Catalysts provide an alternative reaction pathway with lower activation energy.

Answer

Catalysts increase the number of reactant molecules, leading to more frequent collisions.

Answer

Catalysts react with one of the reactants, reducing the overall activation energy.

Answer

Catalysts supply energy to the reaction, directly increasing the reaction rate.

Question 15

In a chemical reaction at constant temperature and pressure, which of the following conditions indicates spontaneity?

Accepted Answer

ΔS > 0 and ΔG < 0

Answer

ΔS > 0 and ΔG > 0

Answer

ΔS < 0 and ΔG < 0

Answer

ΔS < 0 and ΔG > 0

Question 16

The activation energy for a reaction is:

Accepted Answer

The minimum amount of energy that reactants must have to react.

Answer

The amount of energy released when reactants form products.

Answer

The difference in energy between reactants and products.

Answer

The rate at which a reaction occurs.

Question 17

A catalyst is a substance that:

Accepted Answer

Increases the rate of a reaction without being consumed.

Answer

Decreases the rate of a reaction.

Answer

Is consumed in a reaction.

Answer

Is formed in a reaction.

Question 18

The Gibbs free energy change for a reaction is given by the equation ΔG = ΔH - TΔS. What does a negative value of ΔG indicate?

Accepted Answer

The reaction is spontaneous.

Answer

The reaction is non-spontaneous.

Answer

The reaction is at equilibrium.

Answer

The reaction is exothermic.

Question 19

Which of the following is a homogeneous catalyst?

Accepted Answer

Enzymes in biochemical reactions

Answer

Nickel in the hydrogenation of alkenes

Answer

Platinum in the catalytic converter

Answer

Solid catalysts are always heterogeneous.

Question 20

What is the standard enthalpy change of formation of an element in its standard state?

Accepted Answer

Zero

Answer

Always negative

Answer

Always positive

Answer

Depends on the element

Question 21

Identify the correct relationship between enthalpy change (ΔH) and entropy change (ΔS) for a spontaneous process:

Accepted Answer

ΔH < 0 and ΔS > 0

Answer

ΔH > 0 and ΔS < 0

Answer

ΔH < 0 and ΔS < 0

Answer

ΔH > 0 and ΔS > 0

Question 22

Define the activation energy of a reaction:

Accepted Answer

The energy difference between the reactants and the transition state

Answer

The energy difference between the products and the reactants

Answer

The highest energy that the reactants must have to react

Answer

The lowest energy that the reactants must have to react

Question 23

What is the role of a catalyst?

Accepted Answer

Increases the rate of a reaction without being consumed

Answer

Decreases the rate of a reaction without being consumed

Answer

Is consumed in the reaction

Answer

Does not participate in the reaction

Question 24

What is the primary use of the Arrhenius equation?

Accepted Answer

Calculating the activation energy of a reaction

Answer

Calculating the rate constant of a reaction

Answer

Determining the order of a reaction

Answer

Predicting the products of a reaction

Question 25

Identify the unit of entropy:

Accepted Answer

J/mol K

Answer

J/mol

Answer

mol/J

Answer

K/J

Question 26

Characterize a reaction that exhibits an increase in free energy:

Accepted Answer

Non-spontaneous

Answer

Spontaneous

Answer

Equilibrium

Answer

Reversible

Question 27

Which of the following is NOT a catalytic enzyme?

Accepted Answer

Acetylcholine

Answer

Amylase

Answer

Lipase

Answer

Catalase

Question 28

Determine the rate law for a reaction that is first order with respect to both A and B.

Accepted Answer

rate = k[A][B]

Answer

rate = k[A][B]^2

Answer

rate = k[A]^2[B]

Answer

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

Question 29

Identify the conjugate base of HSO4-.

Accepted Answer

SO42-

Answer

H2SO4

Answer

H2O

Answer

OH-

Question 30

Select the correct definition of enthalpy change of formation.

Accepted Answer

The enthalpy change when a substance is formed from its constituent elements in their standard states.

Answer

The enthalpy change when a substance is decomposed into its constituent elements.

Answer

The enthalpy change when a substance is dissolved in water.

Answer

The enthalpy change when a substance undergoes a chemical reaction.

Question 31

Determine the condition for a spontaneous reaction based on the Gibbs free energy change equation (ΔG = ΔH - TΔS).

Accepted Answer

ΔH < 0, ΔS > 0

Answer

ΔH > 0, ΔS > 0

Answer

ΔH < 0, ΔS < 0

Answer

ΔH > 0, ΔS < 0

Question 32

Which of the following characterizes exothermic reactions?

Accepted Answer

Release of heat

Answer

Absorption of heat

Answer

Increase in entropy

Answer

Decrease in entropy

Question 33

Explain how a catalyst influences the activation energy of a reaction.

Accepted Answer

Decreases activation energy, leading to a faster reaction

Answer

Decreases activation energy, leading to a slower reaction

Answer

Increases activation energy, leading to a faster reaction

Answer

Increases activation energy, leading to a slower reaction

Question 34

Identify the primary factor that contributes to the entropy of a system.

Accepted Answer

Number of possible microstates

Answer

Temperature

Answer

Pressure

Answer

Volume

Question 35

How do catalysts affect the activation energy needed for a reaction?

Accepted Answer

Catalysts decrease activation energy, speeding up reactions.

Answer

Catalysts increase activation energy, slowing down reactions.

Answer

Catalysts have no effect on activation energy, so reaction rates stay the same.

Question 36

Define the enthalpy change of a reaction.

Accepted Answer

The difference in energy between the products and reactants

Answer

The energy released during a reaction

Answer

The energy absorbed during a reaction

Answer

The change in entropy during a reaction

Question 37

When the products of a reaction are less ordered than the reactants, what is the sign of the entropy change?

Accepted Answer

Positive

Answer

Negative

Answer

Zero

Answer

It depends on the temperature

Question 38

A negative Gibbs free energy change indicates that a reaction is:

Accepted Answer

Spontaneous

Answer

Non-spontaneous

Answer

At equilibrium

Answer

Reversible

Question 39

What is the minimum energy required for a reaction to occur called?

Accepted Answer

Activation energy

Answer

Gibbs free energy

Answer

Enthalpy change

Answer

Entropy change

Question 40

Which of the following is a characteristic of an exothermic reaction?

Accepted Answer

Heat is released

Answer

Heat is absorbed

Answer

Entropy decreases

Answer

Gibbs free energy decreases

Question 41

The Arrhenius equation relates the rate constant to which two factors?

Accepted Answer

Temperature and activation energy

Answer

Concentration and temperature

Answer

Gibbs free energy and volume

Answer

Entropy change and enthalpy change

Question 42

What is the role of a catalyst in a chemical reaction?

Accepted Answer

Decreases the activation energy of a reaction

Answer

Increases the activation energy of a reaction

Answer

Changes the equilibrium constant of a reaction

Answer

Is consumed during a reaction

Question 43

What is the SI unit of entropy?

Accepted Answer

Kelvin per mole

Answer

Joules

Answer

Moles

Answer

Seconds per mole

Question 44

Which of the following is **not** a type of energy change that can occur during a chemical reaction?

Accepted Answer

Momentum change

Answer

Enthalpy change

Answer

Entropy change

Answer

Free energy change

Question 45

The enthalpy change of a reaction is a measure of the:

Accepted Answer

Heat gained or lost by the surroundings

Answer

Change in internal energy of the system

Answer

Amount of work done by the system

Answer

Activation energy required for the reaction

Question 46

Which of the following factors does **not** affect the entropy of a system?

Accepted Answer

Mass

Answer

Temperature

Answer

Pressure

Answer

Volume

Question 47

A reaction with a negative free energy change is:

Accepted Answer

Spontaneous

Answer

Non-spontaneous

Answer

At equilibrium

Answer

Thermally unstable

Question 48

Which of the following is **not** a factor that can influence the activation energy of a reaction?

Accepted Answer

Volume of the reaction vessel

Answer

Nature of the reactants

Answer

Presence of a catalyst

Answer

Temperature

Question 49

The rate constant for a reaction is a measure of the:

Accepted Answer

Speed of the reaction

Answer

Activation energy of the reaction

Answer

Equilibrium constant of the reaction

Answer

Free energy change of the reaction

Question 50

For an exothermic reaction, the enthalpy change (ΔH) is:

Accepted Answer

Negative

Answer

Positive

Answer

Zero

Answer

Cannot be determined

Question 51

The standard unit for measuring entropy is:

Accepted Answer

Joules per Kelvin (J/K)

Answer

Calories per gram (cal/g)

Answer

Degrees Celsius (°C)

Answer

Moles per liter (mol/L)

Question 52

Gibbs free energy (ΔG) is defined as:

Accepted Answer

ΔH - TΔS

Answer

ΔH + TΔS

Answer

TΔS - ΔH

Answer

ΔS - ΔH

Question 53

Activation energy (Ea) represents:

Accepted Answer

Minimum energy required for a reaction to occur

Answer

Maximum energy released in a reaction

Answer

Difference in energy between reactants and products

Answer

Rate constant of a reaction

Question 54

Which type of catalyst is commonly used in heterogeneous catalysis?

Accepted Answer

Heterogeneous

Answer

Homogeneous

Answer

Auto

Answer

Biological

Question 55

The Arrhenius equation is primarily used to:

Accepted Answer

Calculate the activation energy of a reaction

Answer

Determine the rate constant of a reaction

Answer

Predict the equilibrium constant of a reaction

Answer

Measure the enthalpy change of a reaction

Question 56

Which of the following is a precise definition of the standard enthalpy change of formation for a reaction?

Accepted Answer

The enthalpy change when one mole of a compound is formed from its constituent elements in their standard states

Answer

The change in enthalpy when one mole of a compound is decomposed into its constituent elements

Answer

The enthalpy change when one mole of a compound is combined with its constituent elements

Answer

The enthalpy change when one mole of a compound is formed from its constituent elements in their gaseous states

Question 57

How is entropy related to randomness?

Accepted Answer

Entropy is a measure of the randomness of a system

Answer

Randomness is a measure of the entropy of a system

Answer

Entropy is inversely proportional to randomness

Answer

Randomness is directly proportional to entropy

Question 58

Define the activation energy of a reaction.

Accepted Answer

The minimum energy required for a reaction to occur

Answer

The maximum energy released during a reaction

Answer

The energy change when reactants are converted to products

Answer

The energy change when products are converted to reactants

Question 59

Which of the following is a characteristic of a spontaneous process?

Accepted Answer

Decrease in free energy

Answer

Increase in free energy

Answer

No change in free energy

Answer

Increase in enthalpy

Question 60

How does a catalyst affect the activation energy of a reaction?

Accepted Answer

Decreases the activation energy

Answer

Increases the activation energy

Answer

Has no effect on the activation energy

Answer

Halves the activation energy

Question 61

Design an experiment to determine the order of a reaction with respect to a specific reactant. Describe how you would analyze the data and identify potential sources of error.

Accepted Answer

Vary the concentration of the reactant while keeping other conditions constant. Measure the initial rate of the reaction for each concentration and plot a graph of the initial rate against the concentration. Determine the order of the reaction from the slope of the graph.

Answer

Measure the activation energy of the reaction and use the Arrhenius equation to determine the order of the reaction.

Answer

Use a catalyst to increase the reaction rate and measure the change in the rate of reaction.

Question 62

What is the definition of the standard enthalpy change of a reaction?

Accepted Answer

Change in enthalpy when 1 mole of reactants is completely converted to 1 mole of products under standard conditions

Answer

Change in enthalpy when 1 gram of reactants is partially converted to 1 gram of products under standard conditions

Answer

Change in enthalpy when 1 mole of reactants is completely converted to 1 mole of products under non-standard conditions

Question 63

Which of the following factors has no effect on the rate of a chemical reaction?

Accepted Answer

Pressure of an inert gas

Answer

Surface area of the reactants

Answer

Concentration of the reactants

Answer

Temperature of the reaction

Question 64

Which of the following describes an endothermic reaction?

Accepted Answer

A reaction that absorbs heat from the surroundings

Answer

A reaction that releases heat into the surroundings

Answer

A reaction that absorbs light from the surroundings

Answer

A reaction that does not exchange heat with the surroundings