LESSON 20 & 21: Intro to energy & Free energy

Question 1

What is an isolated system?

Answer 1

An isolated system is one that does not exchange energy or matter with its surroundings.

Question 2

True or False: A closed system can exchange energy but not matter with its surroundings.

Answer 2

True

Question 3

Fill in the blank: An open system allows for the exchange of ______ and ______ with its surroundings.

Answer 3

energy; matter

Question 4

Which type of system is most common in biological processes?

Answer 4

Open system

Question 5

What characterizes a closed system?

Answer 5

A closed system can exchange energy but not matter with its surroundings.

Question 6

Name one example of an isolated system.

Answer 6

A thermos bottle that is perfectly insulated.

Question 7

What is the primary difference between open and closed systems?

Answer 7

Open systems exchange both energy and matter; closed systems exchange only energy.

Question 8

True or False: In an isolated system, total energy remains constant.

Answer 8

True

Question 9

What is a common example of an open system?

Answer 9

A living organism.

Question 10

Complete the statement: In thermodynamics, systems can be classified into three categories: isolated, closed, and ______.

Answer 10

open

Question 11

How do isolated systems interact with their surroundings?

Answer 11

They do not interact at all.

Question 12

Which type of system is often used in laboratory experiments to study thermodynamics?

Answer 12

Closed system

Question 13

True or False: An example of a closed system is a sealed container of gas.

Answer 13

True

Question 14

What role do open systems play in living organisms?

Answer 14

They allow for the intake of nutrients and the expulsion of waste.

Question 15

What happens to energy in an isolated system?

Answer 15

Energy is conserved and cannot be created or destroyed.

Question 16

Name a characteristic of a closed system in thermodynamics.

Answer 16

It can perform work by exchanging energy with its environment.

Question 17

True or False: Isolated systems can be affected by external forces.

Answer 17

False

Question 18

What is an example of a system that is neither closed nor isolated?

Answer 18

A river ecosystem.

Question 19

How do open systems maintain homeostasis?

Answer 19

By continuously exchanging energy and matter with their environment.

Question 20

What is the significance of studying these systems in thermodynamics?

Answer 20

It helps understand energy transfer and transformation in various contexts.

Question 21

What is free energy?

Answer 21

Free energy is the energy in a physical system that can be converted to do work.

Question 22

True or False: Free energy is only relevant in thermodynamics.

Answer 22

False

Question 23

What are the two main types of free energy?

Answer 23

Gibbs free energy and Helmholtz free energy.

Question 24

What does Gibbs free energy (G) indicate?

Answer 24

It indicates the maximum reversible work obtainable from a thermodynamic system at constant temperature and pressure.

Question 25

Fill in the blank: The formula for Gibbs free energy is G = _____ - TS.

Answer 25

H

Question 26

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

Answer 26

It signifies that a process is spontaneous.

Question 27

In which conditions is Helmholtz free energy (A) used?

Answer 27

It is used for systems at constant temperature and volume.

Question 28

True or False: The lower the free energy of a system, the more stable it is.

Answer 28

True

Question 29

What is the relationship between free energy and equilibrium?

Answer 29

At equilibrium, the change in free energy (ΔG) is zero.

Question 30

Multiple Choice: Which of the following factors affects Gibbs free energy? A) Temperature B) Pressure C) Composition D) All of the above

Answer 30

D) All of the above

Question 31

What is the significance of the equilibrium constant (K) in relation to free energy?

Answer 31

The equilibrium constant is related to the standard Gibbs free energy change (ΔG°) by the equation ΔG° = -RT ln(K).

Question 32

Fill in the blank: The standard free energy change (ΔG°) is measured under _____ conditions.

Answer 32

standard

Question 33

What is the effect of temperature on free energy?

Answer 33

Temperature can change the balance between enthalpy and entropy, affecting free energy.

Question 34

True or False: Free energy can be used to predict the direction of a chemical reaction.

Answer 34

True

Question 35

What does the term 'enthalpy' (H) refer to in the context of free energy?

Answer 35

Enthalpy refers to the total heat content of a system.

Question 36

Multiple Choice: Which equation relates enthalpy, entropy, and free energy? A) G = H - TS B) H = G + TS C) TS = H - G D) All of the above

Answer 36

A) G = H - TS

Question 37

What does it mean if a process has a positive ΔG?

Answer 37

It means that the process is non-spontaneous under the given conditions.

Question 38

Fill in the blank: The change in free energy can be calculated using ΔG = ΔH - _____.

Answer 38

TΔS

Question 39

What is the role of entropy (S) in free energy calculations?

Answer 39

Entropy measures the disorder or randomness of a system, which affects the free energy.

Question 40

What is free energy?

Answer 40

Free energy is the energy available to do work in a thermodynamic system at constant temperature and pressure.

Question 41

Which equation relates free energy, enthalpy, and entropy?

Answer 41

The equation is ΔG = ΔH - TΔS, where ΔG is the change in free energy, ΔH is the change in enthalpy, T is the temperature in Kelvin, and ΔS is the change in entropy.

Question 42

True or False: An increase in entropy (ΔS) at constant temperature will always decrease free energy (ΔG).

Answer 42

True.

Question 43

What does a negative ΔG indicate about a reaction?

Answer 43

A negative ΔG indicates that a reaction is spontaneous under the given conditions.

Question 44

Fill in the blank: Enthalpy (H) represents the total _____ of a system.

Answer 44

heat content.

Question 45

How does temperature (T) affect the relationship between enthalpy and entropy in the free energy equation?

Answer 45

As temperature increases, the impact of entropy (TΔS) on free energy becomes more significant.

Question 46

What is the standard state condition for free energy calculations?

Answer 46

The standard state condition is typically 1 bar pressure and a specified temperature, usually 25°C (298 K).

Question 47

True or False: Entropy (S) is a measure of disorder in a system.

Answer 47

True.

Question 48

What happens to free energy when a reaction is at equilibrium?

Answer 48

At equilibrium, ΔG is equal to zero.

Question 49

How is enthalpy (ΔH) defined in thermodynamics?

Answer 49

Enthalpy is defined as the sum of the internal energy of a system plus the product of its pressure and volume.

Question 50

What is the relationship between entropy and the spontaneity of a process?

Answer 50

Processes with an increase in entropy are generally spontaneous.

Question 51

Multiple Choice: Which of the following factors can increase entropy? A) Mixing of gases B) Formation of crystals C) Decreasing temperature

Answer 51

A) Mixing of gases.

Question 52

In the equation ΔG = ΔH - TΔS, what does T represent?

Answer 52

T represents the absolute temperature in Kelvin.

Question 53

What is the significance of a positive ΔG value?

Answer 53

A positive ΔG value indicates that a reaction is non-spontaneous under the given conditions.

Question 54

Fill in the blank: The change in entropy (ΔS) can be calculated using the formula ΔS = _____ / T.

Answer 54

Qrev (the heat absorbed in a reversible process).

Question 55

True or False: Increasing temperature can decrease the spontaneity of a reaction.

Answer 55

False.

Question 56

What does the term 'enthalpy of formation' refer to?

Answer 56

The enthalpy change associated with the formation of one mole of a compound from its elements in their standard states.

Question 57

How does the concept of free energy apply to biological systems?

Answer 57

Free energy is crucial for understanding metabolic processes and energy transfer in living organisms.

Question 58

What is the relationship between temperature and entropy in the context of the second law of thermodynamics?

Answer 58

The second law states that the total entropy of an isolated system can never decrease over time; as temperature increases, entropy tends to increase.

Question 59

What is the definition of entropy in thermodynamics?

Answer 59

Entropy is a measure of the disorder or randomness in a system.

Question 60

True or False: Entropy always increases in an isolated system.

Answer 60

True

Question 61

Fill in the blank: Enthalpy is defined as the sum of the internal energy and _______.

Answer 61

the product of pressure and volume

Question 62

Which of the following statements is true about enthalpy? (A) It is always constant in a chemical reaction. (B) It can change during a chemical reaction at constant pressure. (C) It is irrelevant to physical chemistry.

Answer 62

B

Question 63

What is the relationship between enthalpy change and heat exchange at constant pressure?

Answer 63

The change in enthalpy is equal to the heat exchanged during the process at constant pressure.