Energy Changes: Interactive Quizzes and Learning Resources

Question 1

Which energy type can be both stored and released?

Accepted Answer

Chemical energy

Answer

Light energy

Answer

Thermal energy

Answer

Mechanical energy

Question 2

Design an experiment to investigate how temperature affects the rate of a chemical reaction between sodium thiosulfate and hydrochloric acid.

Accepted Answer

Change the temperature of the reaction and measure how long it takes for the reaction to finish.

Answer

Change the concentration of sodium thiosulfate and measure how long it takes for the reaction to finish.

Answer

Change the volume of the reaction and measure how long it takes for the reaction to finish.

Answer

Change the surface area of the sodium thiosulfate and measure how long it takes for the reaction to finish.

Question 3

How can the enthalpy change of a reaction be used to predict whether the reaction will occur spontaneously? Explain your reasoning.

Accepted Answer

A negative enthalpy change indicates that the reaction is spontaneous in the forward direction.

Answer

The enthalpy change alone determines the spontaneity of a reaction.

Answer

Enthalpy change can only be used to predict spontaneity if the reaction occurs under standard conditions.

Answer

Enthalpy change is only useful for predicting the spontaneity of reactions involving gases.

Question 4

What is the pH of a neutral solution?

Accepted Answer

7

Answer

0

Answer

10

Answer

14

Question 5

What is the activation energy of a reaction?

Accepted Answer

The minimum energy required for a reaction to occur

Answer

The maximum energy released in a reaction

Answer

The rate at which a reaction occurs

Answer

The equilibrium constant for a reaction

Question 6

Which of the following is a catalyst?

Accepted Answer

An enzyme

Answer

A reactant

Answer

A product

Answer

An inhibitor

Question 7

What is the conjugate base of HNO3?

Accepted Answer

NO3-

Answer

H2NO3+

Answer

OH-

Answer

H3O+

Question 8

Which of the following reactions is a redox reaction?

Accepted Answer

Burning of methane

Answer

Neutralisation of an acid and a base

Answer

Precipitation of a metal carbonate

Answer

Dissolving of sugar in water

Question 9

What is the enthalpy change of a reaction?

Accepted Answer

The energy absorbed or released during a reaction

Answer

The rate at which a reaction occurs

Answer

The equilibrium constant for a reaction

Answer

The activation energy of a reaction

Question 10

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

Accepted Answer

Color of the reactants

Answer

Concentration of reactants

Answer

Temperature

Answer

Surface area of reactants

Question 11

The equilibrium constant for a reaction is defined as

Accepted Answer

The ratio of concentrations of products to reactants at equilibrium

Answer

The rate at which the reaction proceeds at equilibrium

Answer

The difference in free energy between reactants and products

Answer

The temperature at which the reaction reaches equilibrium

Question 12

Which of the following is a strong acid?

Accepted Answer

Hydrochloric acid

Answer

Acetic acid

Answer

Carbonic acid

Answer

Ethanoic acid

Question 13

Calculate the pH of a solution with a hydroxide ion concentration of 10^-12 mol/L.

Accepted Answer

12

Answer

0

Answer

7

Answer

14

Question 14

Which of the following is a characteristic of a catalyst?

Accepted Answer

It speeds up the reaction without being consumed

Answer

It is a reactant in the reaction

Answer

It is a product of the reaction

Answer

It inhibits the reaction

Question 15

Determine the oxidation state of nitrogen in nitric acid (HNO3)

Accepted Answer

+5

Answer

+1

Answer

+3

Answer

-3

Question 16

Which species can act as a nucleophile?

Accepted Answer

OH-

Answer

H+

Answer

CH3COOH

Answer

Na+

Question 17

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

Accepted Answer

Color of the reaction mixture

Answer

Surface area of the reactants

Answer

Concentration of the reactants

Answer

Temperature

Question 18

Energy released by a reaction into the surroundings indicates the reaction is:

Accepted Answer

Exothermic

Answer

Endothermic

Answer

Adiabatic

Answer

Isothermal

Question 19

The equilibrium constant, Kc, for a reversible reaction is defined as the:

Accepted Answer

Ratio of products to reactants at equilibrium

Answer

Ratio of reactants to products at equilibrium

Answer

Rate of the forward reaction

Answer

Rate of the reverse reaction

Question 20

Which of the following acids is classified as weak?

Accepted Answer

Acetic acid

Answer

Hydrochloric acid

Answer

Sulfuric acid

Answer

Nitric acid

Question 21

Which substance acts as a buffer in solution?

Accepted Answer

A mixture of sodium acetate and acetic acid

Answer

Sodium chloride

Answer

Potassium hydroxide

Answer

Glucose

Question 22

Which of the following is a sustainable energy source?

Accepted Answer

Solar energy

Answer

Coal

Answer

Natural gas

Answer

Petroleum

Question 23

Catalysts in chemical reactions function to:

Accepted Answer

Decrease the activation energy of the reaction

Answer

Increase the activation energy of the reaction

Answer

Increase the yield of the reaction

Answer

Decrease the rate of the reaction

Question 24

Select the reaction that exemplifies a redox reaction:

Accepted Answer

Rusting of iron

Answer

Neutralization of an acid and a base

Answer

Precipitation of a salt

Answer

Combustion of methane

Question 25

Which process involves a change in the chemical composition of a substance?

Accepted Answer

Burning wood

Answer

Melting ice

Answer

Dissolving salt in water

Answer

Boiling water

Question 26

Which of these substances is classified as an acid?

Accepted Answer

Hydrochloric acid

Answer

Sodium hydroxide

Answer

Sodium chloride

Answer

Water

Question 27

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

Accepted Answer

Calorimetry

Answer

Titration

Answer

Conductivity

Answer

Spectrophotometry

Question 28

What is the primary use of Gibbs free energy change (ΔG)?

Accepted Answer

Predicting the spontaneity of a reaction

Answer

Calculating the equilibrium constant

Answer

Determining the rate of a reaction

Answer

Measuring the enthalpy change

Question 29

Which substance is categorized as a strong electrolyte?

Accepted Answer

Sodium chloride

Answer

Glucose

Answer

Water

Answer

Ethanol

Question 30

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

Accepted Answer

The minimum energy required for a reaction to proceed

Answer

The maximum energy released in a reaction

Answer

The difference in energy between the reactants and products

Answer

The rate constant of a reaction

Question 31

Which chemical reaction releases energy?

Accepted Answer

Exothermic reaction

Answer

Endothermic reaction

Answer

Neutralization reaction

Answer

Redox reaction

Question 32

What is the slowest step in a chemical reaction called?

Accepted Answer

Rate-determining step

Answer

Initial step

Answer

Final step

Answer

Intermediate step

Question 33

What is the ratio of concentrations of products to reactants at equilibrium called?

Accepted Answer

Equilibrium constant

Answer

Rate constant

Answer

Activation energy

Answer

Enthalpy change

Question 34

Which of these is a strong acid?

Accepted Answer

Hydrochloric acid

Answer

Acetic acid

Answer

Carbonic acid

Answer

Sodium hydroxide

Question 35

What is the pH of a neutral solution?

Accepted Answer

7

Answer

0

Answer

14

Answer

It depends on temperature

Question 36

Which reaction is a neutralization reaction?

Accepted Answer

Acid + Base

Answer

Acid + Metal

Answer

Base + Salt

Answer

Metal + Salt

Question 37

What is the purpose of a buffer solution?

Accepted Answer

Maintain a constant pH

Answer

Increase the rate of a reaction

Answer

Decrease the rate of a reaction

Answer

Neutralize acids and bases

Question 38

What is the minimum amount of energy required to start a reaction called?

Accepted Answer

Activation energy

Answer

Enthalpy change

Answer

Rate constant

Answer

Equilibrium constant

Question 39

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

Accepted Answer

Isobatic

Answer

Exothermic

Answer

Endothermic

Answer

Adiabatic

Question 40

What is the equilibrium constant of a chemical reaction?

Accepted Answer

Ratio of product concentrations to reactant concentrations

Answer

Ratio of forward reaction rate to reverse reaction rate

Answer

Temperature at which forward and reverse reactions occur at equal rates

Answer

Enthalpy change of the reaction

Question 41

Among the following acids, which one is the strongest?

Accepted Answer

Hydrochloric acid

Answer

Acetic acid

Answer

Carbonic acid

Answer

Citric acid

Question 42

What is the pH of a solution that is considered neutral?

Accepted Answer

7

Answer

0

Answer

14

Answer

Varies with temperature

Question 43

What is the enthalpy change of a reaction?

Accepted Answer

Heat absorbed or released during the reaction

Answer

Change in free energy of the reaction

Answer

Equilibrium constant of the reaction

Answer

Reaction rate

Question 44

Which of the following processes is considered spontaneous?

Accepted Answer

Process with a decrease in free energy

Answer

Process with an increase in free energy

Answer

Process at equilibrium

Answer

Process requiring an external energy input

Question 45

What is the activation energy of a reaction?

Accepted Answer

Minimum energy required for a reaction to occur

Answer

Maximum energy released by a reaction

Answer

Difference in energy between reactants and products

Answer

Reaction rate constant

Question 46

The rate of a chemical reaction is defined as:

Accepted Answer

The change in concentration of reactants or products per unit time

Answer

The change in temperature per unit time

Answer

The change in pressure per unit time

Answer

The change in volume per unit time

Question 47

The equilibrium constant for a reaction is:

Accepted Answer

The ratio of the concentrations of products to the concentrations of reactants at equilibrium

Answer

The rate of the forward reaction divided by the rate of the reverse reaction

Answer

The amount of energy released or absorbed in the reaction

Answer

The temperature at which the reaction reaches equilibrium

Question 48

Which of the following is a strong acid?

Accepted Answer

Hydrochloric acid

Answer

Acetic acid

Answer

Carbonic acid

Answer

Ammonium hydroxide

Question 49

The pH of a neutral solution is:

Accepted Answer

7

Answer

0

Answer

14

Answer

28

Question 50

Which of the following is the difference between an exothermic and endothermic reaction?

Accepted Answer

Exothermic reactions release energy, while endothermic reactions absorb energy.

Answer

Endothermic reactions release energy, while exothermic reactions absorb energy.

Answer

Exothermic reactions occur at higher temperatures than endothermic reactions.

Answer

Endothermic reactions occur at higher temperatures than exothermic reactions.

Question 51

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

Is consumed in a reaction

Answer

Is not involved in a reaction

Question 52

The activation energy of a reaction is:

Accepted Answer

The minimum amount of energy that must be supplied to the reactants in order for the reaction to occur

Answer

The maximum amount of energy that can be released in a reaction

Answer

The energy difference between the reactants and products

Answer

The rate at which the reaction occurs

Question 53

In an endothermic reaction, the system:

Accepted Answer

Absorbs energy

Answer

Releases energy

Answer

Does not exchange energy with the surroundings

Answer

Releases large amounts of energy

Question 54

The equilibrium constant of a reaction represents:

Accepted Answer

The relative concentrations of reactants and products at equilibrium

Answer

The amount of product formed

Answer

The reaction rate

Answer

The activation energy of the reaction

Question 55

A catalyst is a substance that:

Accepted Answer

Lowers the activation energy of a reaction

Answer

Increases the activation energy of a reaction

Answer

Is consumed in a reaction

Answer

Is produced in a reaction

Question 56

The activation energy of a reaction is the:

Accepted Answer

Minimum energy required for the reaction to occur

Answer

Maximum energy released in a reaction

Answer

Energy difference between reactants and products

Answer

Energy needed to break reactant bonds

Question 57

Which reaction is a redox reaction?

Accepted Answer

CH4 + 2O2 → CO2 + 2H2O

Answer

2Na + Cl2 → 2NaCl

Answer

NaOH + HCl → NaCl + H2O

Answer

CaCO3 → CaO + CO2

Question 58

Which of the following is a buffer solution?

Accepted Answer

Resists changes in pH

Answer

Has high hydrogen ion concentration

Answer

Has high hydroxide ion concentration

Answer

Is neutral

Question 59

The enthalpy change of a reaction is the:

Accepted Answer

Heat released or absorbed by the reaction

Answer

Energy needed to break reactant bonds

Answer

Energy difference between reactants and products

Answer

Reaction rate

Question 60

Why is it essential to study reaction mechanisms in chemistry?

Accepted Answer

To understand the reaction's step-by-step process.

Answer

To calculate the reaction's overall speed.

Answer

To identify the reaction's end products.

Answer

To determine the reaction's activation energy.

Question 61

Explain the correlation between the boiling points of liquids and the strength of their intermolecular forces.

Accepted Answer

Liquids characterized by stronger intermolecular forces exhibit higher boiling points.

Answer

Liquids with weaker intermolecular forces possess higher boiling points.

Answer

The boiling points of liquids are unrelated to the strength of their intermolecular forces.

Question 62

What is the primary importance of a reaction mechanism in understanding a chemical reaction?

Accepted Answer

Explaining the step-by-step pathway of a reaction

Answer

Predicting the speed of a reaction

Answer

Identifying the products of a reaction

Question 63

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

Accepted Answer

Presence of a spectator ion

Answer

Temperature

Answer

Surface area of reactants

Answer

Concentration of reactants

Question 64

Which of the following is an example of a strong acid?

Accepted Answer

Hydrochloric acid

Answer

Ethanoic acid

Answer

Carbonic acid

Answer

Citric acid