Chemical Reactions and Energy: Interactive Quizzes and Learning Materials

Question 1

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

Accepted Answer

Volume of the reaction vessel

Answer

Concentration of reactants

Answer

Temperature

Answer

Presence of a catalyst

Question 2

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

Accepted Answer

Zero

Answer

Positive

Answer

Negative

Answer

Dependent on the element

Question 3

Which of the following reactions is endothermic?

Accepted Answer

Freezing of water

Answer

Combustion of propane

Answer

Neutralization of hydrochloric acid with sodium hydroxide

Answer

Dissolution of potassium chloride in water

Question 4

What is the primary use of Hess's law?

Accepted Answer

To predict the enthalpy change of a reaction using enthalpy changes of other reactions

Answer

To calculate the activation energy of a reaction

Answer

To determine the rate of a reaction

Answer

To identify the products of a reaction

Question 5

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

Accepted Answer

Molecular weight of the reactants

Answer

Concentration of the reactants

Answer

Temperature

Answer

Surface area of reactants in contact

Question 6

What is the sign of the enthalpy change for an exothermic reaction?

Accepted Answer

Negative

Answer

Positive

Answer

Zero

Answer

Variable

Question 7

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

Accepted Answer

Absorbs heat

Answer

Releases heat

Answer

Has no change in temperature

Answer

Produces a solid product

Question 8

What is the relationship between the activation energy of a reaction and the rate of reaction?

Accepted Answer

The higher the activation energy, the slower the reaction

Answer

The higher the activation energy, the faster the reaction

Answer

The activation energy has no effect on the reaction rate

Answer

The activation energy is inversely proportional to the reaction rate

Question 9

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

Accepted Answer

Precipitation reaction

Answer

Acid-base reaction

Answer

Redox reaction

Answer

Synthesis reaction

Question 10

Which of the following is a redox reaction?

Accepted Answer

CH₄ + 2O₂ → CO₂ + 2H₂O

Answer

2Na + Cl₂ → 2NaCl

Answer

HCl + NaOH → NaCl + H₂O

Answer

CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

Question 11

The unit of enthalpy is:

Accepted Answer

Joules per mole

Answer

Calories per gram

Answer

Kilojoules per litre

Answer

Watts per second

Question 12

One application of Hess's law is:

Accepted Answer

Calculating the enthalpy change of a reaction that cannot be measured directly

Answer

Predicting the products of a reaction

Answer

Determining the equilibrium constant of a reaction

Answer

Measuring the rate of a reaction

Question 13

Which of the following accurately describes an exothermic reaction?

Accepted Answer

Releases heat into the surroundings

Answer

Absorbs heat from the surroundings

Answer

Has a positive enthalpy change

Answer

Has a negative enthalpy change

Question 14

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

Accepted Answer

Electrical current

Answer

Temperature

Answer

Reactant concentration

Answer

Reactant surface area

Question 15

What is the general trend observed in enthalpy change during bond formation?

Accepted Answer

Negative

Answer

Positive

Answer

Zero

Answer

Variable

Question 16

Which technique is used to measure the enthalpy change of a reaction?

Accepted Answer

Calorimetry

Answer

Spectroscopy

Answer

Titration

Answer

Gas chromatography

Question 17

What is the primary application of Hess's law?

Accepted Answer

Predicting enthalpy changes of reactions

Answer

Determining the rate of reactions

Answer

Measuring the equilibrium constant of reactions

Answer

Calculating the activation energy of reactions

Question 18

When chemical bonds break and form in a reaction, what happens to the energy involved?

Accepted Answer

Energy can be released or absorbed, depending on the bond strengths.

Answer

Energy is always released.

Answer

Energy is always absorbed.

Question 19

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

Accepted Answer

Releases heat

Answer

Absorbs heat

Answer

Produces a lower temperature

Answer

Requires an external energy source

Question 20

When a reaction releases heat, what is the sign of its enthalpy change?

Accepted Answer

Positive

Answer

Negative

Answer

Zero

Answer

Cannot be determined

Question 21

How can Hess's law be used in chemistry?

Accepted Answer

To predict the enthalpy change of a reaction

Answer

To determine the activation energy of a reaction

Answer

To predict the rate of a reaction

Answer

To measure the equilibrium constant of a reaction

Question 22

Which of the following reactions occurs in a single phase?

Accepted Answer

Dissolution of sugar in water

Answer

Rusting of iron

Answer

Burning of wood

Answer

Precipitation of silver chloride

Question 23

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

Accepted Answer

Increase the rate of the reaction but not be consumed

Answer

Increase the activation energy of the reaction

Answer

Decrease the activation energy of the reaction

Answer

Change the products of the reaction

Question 24

What differentiates a spontaneous reaction from a non-spontaneous reaction?

Accepted Answer

Spontaneous reactions occur with a decrease in free energy, while non-spontaneous reactions occur with an increase in free energy.

Answer

Spontaneous reactions occur with an increase in entropy, while non-spontaneous reactions occur with a decrease in entropy.

Answer

Spontaneous reactions are always fast, while non-spontaneous reactions are always slow.

Answer

Spontaneous reactions are always exothermic, while non-spontaneous reactions are always endothermic.

Question 25

Which of the following reactions is endothermic?

Accepted Answer

Dissolution of sodium hydroxide in water

Answer

Combustion of methane

Answer

Neutralization of an acid with a base

Answer

Precipitation of a salt from a solution

Question 26

What is the primary purpose of a catalyst?

Accepted Answer

To decrease the activation energy of a reaction

Answer

To increase the activation energy of a reaction

Answer

To provide an alternative pathway for a reaction

Answer

To prevent a reaction from occurring

Question 27

What is the enthalpy change of combustion reactions generally?

Accepted Answer

Positive

Answer

Negative

Answer

Zero

Answer

Can be either positive or negative

Question 28

What is the oxidizing agent in the reaction: Fe + 2HCl → FeCl₂ + H₂?

Accepted Answer

HCl

Answer

Fe

Answer

FeCl₂

Answer

H₂

Question 29

What is the conjugate acid of ammonia?

Accepted Answer

Ammonium ion

Answer

Amide ion

Answer

Hydroxide ion

Answer

Hydronium ion

Question 30

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

Accepted Answer

Volume of the reactants

Answer

Concentration of the reactants

Answer

Nature of the reactants

Answer

Temperature

Question 31

Which of the following processes releases heat and is therefore considered exothermic?

Accepted Answer

Reaction of calcium with water

Answer

Melting of ice

Answer

Vaporization of water

Answer

Condensation of water vapor

Question 32

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

Accepted Answer

Color of the reaction mixture

Answer

Concentration of reactants

Answer

Temperature

Answer

Surface area of reactants

Question 33

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

Accepted Answer

Reaction of a metal with oxygen

Answer

Neutralization of an acid with a base

Answer

Precipitation of a salt

Answer

Decomposition of water

Question 34

What is the activation energy of a reaction?

Accepted Answer

The minimum amount of energy required to start a reaction

Answer

The energy released when a reaction occurs

Answer

The energy absorbed when a reaction occurs

Answer

The difference in energy between the reactants and products of a reaction

Question 35

Which of the following substances acts as a catalyst?

Accepted Answer

Manganese dioxide

Answer

Hydrochloric acid

Answer

Sodium hydroxide

Answer

Sodium chloride

Question 36

What is the primary effect of a catalyst on a chemical reaction?

Accepted Answer

Increases the rate of the reaction

Answer

Decreases the rate of the reaction

Answer

Does not affect the rate of the reaction

Answer

Reverses the direction of the reaction

Question 37

Which of the following is not a type of chemical reaction?

Accepted Answer

Transfusion

Answer

Combustion

Answer

Decomposition

Answer

Neutralization

Question 38

The enthalpy change of a reaction is:

Accepted Answer

The difference in energy content between products and reactants

Answer

The amount of energy released or absorbed during a reaction

Answer

The rate at which a reaction proceeds

Answer

The temperature at which a reaction occurs

Question 39

Hess's law states that:

Accepted Answer

The enthalpy change of a reaction is equal to the sum of the enthalpy changes of the individual steps

Answer

The enthalpy change of a reaction is independent of the pathway taken

Answer

The rate of a reaction is proportional to its enthalpy change

Answer

The equilibrium constant of a reaction is related to its enthalpy change

Question 40

Which of the following reactions is exothermic?

Accepted Answer

Combustion of methane

Answer

Dissolution of sodium chloride in water

Answer

Neutralization of an acid and a base

Answer

Evaporation of water

Question 41

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

Accepted Answer

Solvent used

Answer

Temperature

Answer

Concentration of reactants

Answer

Surface area of reactants

Question 42

Which of the following is a catalyst?

Accepted Answer

A substance that increases the rate of a reaction without being consumed

Answer

A substance that decreases the rate of a reaction

Answer

A product of a reaction

Answer

A reactant in a reaction

Question 43

Which of the following is an endothermic reaction?

Accepted Answer

Evaporation of water

Answer

Combustion of methane

Answer

Dissolution of sodium chloride in water

Answer

Neutralization of an acid and a base

Question 44

The enthalpy change of a reaction is defined as the:

Accepted Answer

Heat absorbed or released by the reaction at constant pressure

Answer

Change in internal energy of the system at constant volume

Answer

Change in free energy of the system

Answer

Change in entropy of the system

Question 45

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

Accepted Answer

Color of the reaction mixture

Answer

Temperature

Answer

Concentration of reactants

Answer

Surface area of reactants

Question 46

Hess's Law states that:

Accepted Answer

The total enthalpy change of a reaction is independent of the pathway taken

Answer

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

Answer

The equilibrium constant of a reaction is constant at a given temperature

Answer

The entropy change of a reaction is always positive

Question 47

The equilibrium constant of a reaction is:

Accepted Answer

The ratio of the concentrations of reactants to products at equilibrium

Answer

The ratio of the rates of the forward and reverse reactions

Answer

The change in free energy of the reaction

Answer

The enthalpy change of the reaction

Question 48

Which of the following is a catalyst?

Accepted Answer

Iron oxide

Answer

Sodium chloride

Answer

Hydrogen peroxide

Answer

Water

Question 49

The activation energy of a reaction is the:

Accepted Answer

Minimum energy required for the reaction to occur

Answer

Maximum energy released by the reaction

Answer

Change in entropy of the reaction

Answer

Equilibrium constant of the reaction

Question 50

The Gibbs free energy of a reaction is:

Accepted Answer

The difference between the enthalpy and entropy changes of the reaction

Answer

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

Answer

The change in free energy of the reaction

Answer

The equilibrium constant of the reaction