Thermodynamics Quizzes: Master Energy and Its Transformations

Question 1

Which of the following is true about the change in internal energy of a system?

Accepted Answer

It is equal to the heat added to the system minus the work done by the system.

Answer

It can never be negative.

Answer

It is equal to the difference in enthalpy between the final and initial states.

Answer

It is always zero.

Question 2

A system undergoes a process in which it absorbs 100 J of heat and does 50 J of work on its surroundings. What is the change in internal energy of the system?

Accepted Answer

50 J

Answer

100 J

Answer

150 J

Answer

200 J

Question 3

Which of the following is NOT a spontaneous process?

Accepted Answer

Water freezing at room temperature

Answer

Ice melting at room temperature

Answer

A hot object cooling down

Answer

A cold object warming up

Question 4

What is the entropy change of a system that goes from a liquid state to a crystalline solid state?

Accepted Answer

Decreases

Answer

Increases

Answer

Remains the same

Answer

Cannot be determined from the given information

Question 5

Which of the following is a violation of the Third Law of Thermodynamics?

Accepted Answer

The temperature of a system can never reach absolute zero.

Answer

The entropy of a perfect crystal is zero at absolute zero.

Answer

No heat can be extracted from a system at absolute zero.

Answer

The heat capacity of a system approaches infinity as the temperature approaches absolute zero.

Question 6

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

Accepted Answer

Volume of the reaction vessel

Answer

Temperature

Answer

Pressure

Answer

Initial concentrations of reactants

Question 7

How does entropy impact both the equilibrium constant and the extent to which a chemical reaction proceeds?

Accepted Answer

Entropy favors reactions that increase the randomness of the system.

Answer

Entropy favors reactions that decrease the randomness of the system.

Answer

Entropy has no effect on the equilibrium constant.

Answer

Entropy has no effect on the reaction yield.

Question 8

According to the first law of thermodynamics, which of the following is true?

Accepted Answer

Energy can neither be created nor destroyed.

Answer

The entropy of an isolated system increases over time.

Answer

Heat always flows from cold to hot objects.

Answer

The change in internal energy of a system is equal to the work done by the system.

Question 9

What is the standard free energy change for a reaction at equilibrium?

Accepted Answer

Zero

Answer

Positive

Answer

Negative

Answer

Cannot be determined without additional information.

Question 10

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

Accepted Answer

Volume of the reaction vessel

Answer

Temperature

Answer

Concentration of reactants

Answer

Presence of a catalyst

Question 11

What is the change in entropy when a substance undergoes a transition from a solid to a liquid state?

Accepted Answer

Positive

Answer

Negative

Answer

Zero

Answer

Varies depending on the substance.

Question 12

How are heat and internal energy distinct?

Accepted Answer

Heat is energy transferred between objects, while internal energy is the total energy of the particles within an object.

Answer

Internal energy is energy transferred between objects, while heat is the total energy of the particles within an object.

Answer

Heat and internal energy are essentially the same concept.

Answer

Internal energy is a measure of disorder, while heat is a measure of the total energy of a system.

Question 13

Which of the following is an example of an exothermic process?

Accepted Answer

Combustion of methane

Answer

Melting of ice

Answer

Sublimation of dry ice

Answer

Photosynthesis of glucose

Question 14

What is the change in the system's internal energy when work is done on the system?

Accepted Answer

Work done on the system

Answer

Work done by the system

Answer

Heat added to the system

Answer

Heat lost by the system

Question 15

In a spontaneous exothermic reaction, the entropy change of the surroundings is:

Accepted Answer

Positive

Answer

Negative

Answer

Zero

Answer

Cannot be determined

Question 16

Which statement is NOT a consequence of the second law of thermodynamics?

Accepted Answer

The equilibrium constant for a reaction is always greater than zero.

Answer

The total entropy of an isolated system always increases.

Answer

Heat flows spontaneously from a region of high temperature to a region of low temperature.

Answer

No process is 100% efficient.

Question 17

A reaction that occurs spontaneously at a given temperature and pressure always has a:

Accepted Answer

Negative ΔG

Answer

Positive ΔG

Answer

Positive ΔS

Answer

Negative ΔS

Question 18

What is the equilibrium constant expression for the reaction A + 2B <=> C + D?

Accepted Answer

K = [C][D]/[A][B]^2

Answer

K = [A][B]^2/[C][D]

Answer

K = [A][B]

Answer

K = [C][D]

Question 19

Which of the following is the definition of the standard free energy change (ΔG°) for a reaction?

Accepted Answer

The free energy change under standard conditions

Answer

The free energy change under non-standard conditions

Answer

The enthalpy change under standard conditions

Answer

The entropy change under standard conditions

Question 20

The third law of thermodynamics states that:

Accepted Answer

The entropy of a perfect crystal at absolute zero is zero.

Answer

The enthalpy of a reaction cannot be negative.

Answer

The Gibbs free energy of a system at equilibrium is zero.

Answer

The entropy of the universe is always decreasing.

Question 21

The enthalpy change (ΔH) of a reaction is:

Accepted Answer

Equal to the heat flow at constant pressure

Answer

Equal to the heat flow at constant volume

Answer

Equal to the work done by the system

Answer

Equal to the internal energy change

Question 22

Which of the following is a statement of the First Law of Thermodynamics?

Accepted Answer

The total energy of an isolated system remains constant.

Answer

Energy can be created but not destroyed.

Answer

Heat is a form of energy that can be transferred between objects.

Answer

The entropy of a closed system always increases.

Question 23

What is the sign of the entropy change when a gas expands adiabatically?

Accepted Answer

Positive, as the gas expands and occupies more space.

Answer

Negative, as the gas compresses and loses energy.

Answer

Zero, as the process is adiabatic and there is no heat transfer.

Answer

It depends on the temperature of the gas.

Question 24

Which of the following reactions is exothermic?

Accepted Answer

The combustion of methane gas (CH₄) with oxygen (O₂) to produce carbon dioxide (CO₂) and water (H₂O)

Answer

The decomposition of water (H₂O) into hydrogen (H₂) and oxygen (O₂)

Answer

The photosynthesis of glucose (C₆H₁₂O₆) by plants using sunlight

Answer

The melting of ice (H₂O) at room temperature

Question 25

What is the free energy change for a reaction at equilibrium?

Accepted Answer

Zero, as the forward and reverse reactions occur at equal rates.

Answer

Positive, indicating that the reaction is not spontaneous.

Answer

Negative, suggesting that the reaction can proceed spontaneously.

Answer

It depends on the temperature and concentration of the reactants and products.

Question 26

What is the effect of increasing temperature on the equilibrium constant for an exothermic reaction?

Accepted Answer

It decreases, as the reverse reaction is favored at higher temperatures.

Answer

It increases, as the forward reaction is favored at higher temperatures.

Answer

It remains constant, as the equilibrium constant is independent of temperature.

Answer

It depends on the specific reaction being considered.

Question 27

Which of the following is a closed system?

Accepted Answer

A sealed container with a gas inside

Answer

A room with people breathing and moving around

Answer

A car engine running and exchanging heat with the surroundings

Answer

A pot of boiling water

Question 28

What is the molar entropy of a perfect crystal at absolute zero?

Accepted Answer

Zero, as the crystal is in a state of maximum order.

Answer

Positive, as the crystal has some degree of disorder.

Answer

Negative, indicating that the crystal is highly disordered.

Answer

Infinite, as the entropy of a perfect crystal is undefined.

Question 29

Which of the following is not a consequence of the second law of thermodynamics?

Accepted Answer

The universe is contracting.

Answer

Heat flows spontaneously from hot to cold objects.

Answer

Entropy increases in all spontaneous processes.

Answer

No process is 100% efficient.

Question 30

Which of the following describes an exothermic process?

Accepted Answer

Heat is released into the surroundings.

Answer

Heat is absorbed from the surroundings.

Answer

The enthalpy of the system increases.

Answer

The entropy of the system decreases.

Question 31

Which of the following equations correctly expresses the change in Gibbs free energy?

Accepted Answer

ΔG = ΔH - TΔS

Answer

ΔG = ΔH + TΔS

Answer

ΔG = -TΔH

Answer

ΔG = ΔS/T

Question 32

Which factor does not affect the equilibrium constant of a reaction?

Accepted Answer

Catalyst

Answer

Temperature

Answer

Pressure

Answer

Concentration of reactants and products

Question 33

Which of the following expressions correctly represents the efficiency of a heat engine?

Accepted Answer

Efficiency = (Work output) / (Heat input)

Answer

Efficiency = (Heat input) / (Work output)

Answer

Efficiency = (Change in entropy) / (Change in temperature)

Answer

Efficiency = (Work done) / (Heat transferred)

Question 34

When determining the direction of a chemical reaction, which factor is considered the most influential?

Accepted Answer

Gibbs free energy change

Answer

Enthalpy change

Answer

Entropy change

Answer

Activation energy

Question 35

Which application demonstrates the role of Gibbs free energy in predicting the feasibility of biochemical processes?

Accepted Answer

Predicting the direction of spontaneous reactions under specified temperature and pressure conditions.

Answer

Estimating the maximum work obtainable from a chemical reaction under specific conditions.

Answer

Calculating the equilibrium constant for a given reaction.

Answer

Determining the efficiency of energy conversion in biological systems.

Question 36

Which statement does NOT represent the Second Law of Thermodynamics?

Accepted Answer

Free energy change equals enthalpy change.

Answer

Entropy of an isolated system increases over time.

Answer

Heat cannot flow spontaneously from cold to hot.

Answer

Heat engine efficiency is always less than 100%.

Question 37

Which statement contradicts the Second Law of Thermodynamics?

Accepted Answer

Energy is conserved in isolated systems.

Answer

Entropy increases in spontaneous processes.

Answer

Heat flows spontaneously from hot to cold objects.

Answer

No process can be perfectly efficient.

Question 38

The first law of thermodynamics states that energy is:

Accepted Answer

Conserved

Answer

Destroyed

Answer

Created

Answer

Transferred

Question 39

Entropy is a measure of:

Accepted Answer

Disorder or randomness

Answer

Pressure

Answer

Energy

Answer

Volume

Question 40

According to the third law of thermodynamics, the entropy of a perfect crystal at absolute zero is:

Accepted Answer

Zero

Answer

Infinite

Answer

Negative

Question 41

An exothermic reaction is one in which:

Accepted Answer

Heat is released

Answer

Heat is absorbed

Answer

Entropy increases

Answer

Gibbs free energy decreases

Question 42

The Gibbs free energy change is a measure of:

Accepted Answer

Reaction spontaneity under specified conditions

Answer

Reaction enthalpy

Answer

Reaction entropy

Answer

Reaction rate

Question 43

The equilibrium constant for a reaction provides information about:

Accepted Answer

Relative amounts of reactants and products at equilibrium

Answer

Enthalpy change

Answer

Reaction rate

Answer

Free energy change

Question 44

A colligative property is a property that depends on:

Accepted Answer

Concentration of solute particles

Answer

Volume

Answer

Temperature

Answer

Pressure

Question 45

Which type of thermodynamic system can exchange both energy and matter with its surroundings?

Accepted Answer

Open system

Answer

Isolated system

Answer

Adiabatic system

Answer

Closed system

Question 46

The first law of thermodynamics states that:

Accepted Answer

Energy cannot be created or destroyed, only transferred or transformed.

Answer

Energy is always lost during transformations.

Answer

Energy can be destroyed but not created.

Answer

Energy can be created but not destroyed.

Question 47

Which of the following processes releases heat to the surroundings?

Accepted Answer

Condensation

Answer

Evaporation

Answer

Melting

Answer

Sublimation

Question 48

Entropy is a thermodynamic property that measures a system's:

Accepted Answer

Disorder or randomness

Answer

Heat capacity

Answer

Average kinetic energy of particles

Answer

Total energy content

Question 49

The second law of thermodynamics states that:

Accepted Answer

The total entropy of an isolated system always increases over time.

Answer

Heat always flows from a cold object to a hot object.

Answer

The entropy of a system can decrease spontaneously.

Answer

Energy can be created in a closed system.

Question 50

Gibbs free energy (ΔG) is a thermodynamic function that predicts the spontaneity of a process at:

Accepted Answer

Constant temperature and pressure

Answer

Constant volume and temperature

Answer

Constant pressure and volume

Answer

Variable temperature and pressure

Question 51

The third law of thermodynamics states that:

Accepted Answer

The entropy of a perfect crystal at absolute zero (0 Kelvin) is zero.

Answer

Entropy can never be zero.

Answer

The entropy of any system at absolute zero is zero.

Answer

The entropy of a system always increases with temperature.