# Chemistry Ch16&17 Exam

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• 1.

### For a process, the enthalpy change of a system is 1.25 x 105 J and the entropy change is 300.0 J/K. Calculate the free energy change of the system at 290 K.

• A.

9.2x105 J

• B.

3.8x104 J

• C.

1.03x106 J

• D.

1.1x105 J

B. 3.8x104 J
Explanation
The free energy change of a system can be calculated using the equation Î”G = Î”H - TÎ”S, where Î”H is the enthalpy change, Î”S is the entropy change, and T is the temperature. Plugging in the given values, we get Î”G = 1.25 x 105 J - 290 K x 300.0 J/K = 1.25 x 105 J - 87,000 J = 38,000 J. Therefore, the free energy change of the system at 290 K is 3.8 x 104 J.

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• 2.

### For a process, the enthalpy change and the entropy change of the system is 173000 J and its entropy change is 210 J/K. Calculate the free energy change of the system at 298 K.

• A.

9.2x105 J

• B.

3.8x104 J

• C.

1.03x106 J

• D.

1.1x105 J

D. 1.1x105 J
Explanation
The free energy change (Î”G) can be calculated using the equation Î”G = Î”H - TÎ”S, where Î”H is the enthalpy change, Î”S is the entropy change, and T is the temperature in Kelvin. Plugging in the given values, Î”H = 173000 J, Î”S = 210 J/K, and T = 298 K, we can calculate Î”G = 173000 J - (298 K)(210 J/K) = 173000 J - 62580 J = 110420 J. Therefore, the correct answer is 1.1x105 J.

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• 3.

### Rice contains 245 nutritional Calories. Calculate the energy in joules.

• A.

9.2x105 J

• B.

3.8x104 J

• C.

1.03x106 J

• D.

1.1x105 J

C. 1.03x106 J
Explanation
The energy content of rice is calculated by converting the nutritional calories to joules. One nutritional calorie is equivalent to 4.184 joules. Therefore, to calculate the energy in joules, we multiply the nutritional calories by 4.184. In this case, 245 nutritional calories multiplied by 4.184 equals 1.03x106 joules.

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• 4.

### A burger contains 220 nutritional Calories. Convert this energy into joules.

• A.

9.2x105 J

• B.

3.8x104 J

• C.

1.03x106 J

• D.

1.1x105 J

A. 9.2x105 J
Explanation
The correct answer is 9.2x105 J. To convert calories to joules, we use the conversion factor 1 calorie = 4.184 joules. Therefore, we can calculate the energy in joules by multiplying the number of calories by 4.184. In this case, 220 calories multiplied by 4.184 gives us 9.2x105 joules.

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• 5.

### A(n) ____________________ is a balanced chemical equation that includes the physical states of all reactants and products and the energy change that accompanies the reaction.

• A.

Thermochemical equation

• B.

Enthalpy of combustion

• C.

Molar enthalpy of vaporization

• D.

Molar enthalpy of fusion

A. Thermochemical equation
Explanation
A thermochemical equation is a balanced chemical equation that includes the physical states of all reactants and products and the energy change that accompanies the reaction. It provides information about the heat energy involved in a chemical reaction, including whether the reaction is exothermic (releases heat) or endothermic (absorbs heat). Thermochemical equations are important in understanding the energetics of chemical reactions and can be used to calculate heat transfer and enthalpy changes.

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• 6.

### The conversion of a gas to a liquid involves the ____________________.

• A.

Thermochemical equation

• B.

Enthalpy of combustion

• C.

Molar enthalpy of vaporization

• D.

Molar enthalpy of fusion

C. Molar enthalpy of vaporization
Explanation
The conversion of a gas to a liquid involves the molar enthalpy of vaporization. This is the amount of heat energy required to convert one mole of a substance from its gaseous state to its liquid state at a constant temperature and pressure. It represents the energy needed to overcome the intermolecular forces holding the gas molecules together and form a liquid.

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• 7.
• A.

Thermochemical equation

• B.

Enthalpy of combustion

• C.

Molar enthalpy of vaporization

• D.

Molar enthalpy of fusion

A. Thermochemical equation
Explanation
A thermochemical equation is a balanced chemical equation that includes the enthalpy change (heat transfer) associated with the reaction. It represents the energy changes that occur during a chemical reaction, including heat absorbed or released. Thermochemical equations are important in studying the energy relationships and reactions in chemistry. They allow us to calculate the amount of heat produced or absorbed in a reaction, which is crucial for understanding and predicting the behavior of chemical reactions.

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• 8.

### Converting two moles of a liquid to a solid requires an amount of energy that is twice the ____________________.

• A.

Thermochemical equation

• B.

Enthalpy of combustion

• C.

Molar enthalpy of vaporization

• D.

Molar enthalpy of fusion

D. Molar enthalpy of fusion
Explanation
When converting a liquid to a solid, the process is known as fusion. The molar enthalpy of fusion represents the amount of energy required to convert one mole of a substance from a liquid to a solid at its melting point. Since the question states that two moles of the liquid are being converted to a solid, the amount of energy required would be twice the molar enthalpy of fusion. Therefore, the correct answer is molar enthalpy of fusion.

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• 9.

### The ____________________ is the heat required to melt one mole of a solid substance.

• A.

Thermochemical equation

• B.

Enthalpy of combustion

• C.

Molar enthalpy of vaporization

• D.

Molar enthalpy of fusion

D. Molar enthalpy of fusion
Explanation
The molar enthalpy of fusion is the heat required to melt one mole of a solid substance.

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• 10.

### The ____________________ is the heat required to vaporize one mole of a liquid.

• A.

Thermochemical equation

• B.

Enthalpy of combustion

• C.

Molar enthalpy of vaporization

• D.

Molar enthalpy of fusion

C. Molar enthalpy of vaporization
Explanation
The molar enthalpy of vaporization refers to the amount of heat energy needed to convert one mole of a liquid into its gaseous state at a constant temperature and pressure.

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• 11.

### The enthalpy change for the complete burning of one mole of a substance is the ____________________.

• A.

Thermochemical equation

• B.

Enthalpy of combustion

• C.

Molar enthalpy of vaporization

• D.

Molar enthalpy of fusion

B. Enthalpy of combustion
Explanation
The enthalpy change for the complete burning of one mole of a substance is referred to as the enthalpy of combustion. This term specifically describes the heat energy released or absorbed during the combustion process. It is a measure of the amount of energy released when one mole of a substance reacts completely with oxygen.

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• 12.

### When a gas condenses to a liquid, heat is ____________________ to the surroundings

• A.

Cool

• B.

Released

• C.

Absorbs

• D.

Heat

B. Released
Explanation
When a gas condenses to a liquid, heat is released to the surroundings. This is because during the process of condensation, the gas molecules lose energy and come closer together, forming a liquid. The excess energy is released in the form of heat, which is transferred to the surrounding environment.

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• 13.
• A.

Cool

• B.

Released

• C.

Absorbs

• D.

Heat

D. Heat
• 14.

### If it takes 100 joules to melt a piece of ice, ____________________ must be absorbed by the ice.

• A.

Cool

• B.

Released

• C.

Absorbs

• D.

Heat

D. Heat
Explanation
When a piece of ice is melted, it requires the absorption of heat energy. This is because heat is the form of energy that is needed to break the intermolecular bonds holding the ice molecules together. Therefore, in order for the ice to melt and transition from a solid to a liquid state, it must absorb a certain amount of heat energy, which in this case is 100 joules.

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• 15.

### If you put an ice cube in a glass of soda pop, the heat absorbed by the ice will cause the ice to melt, and the soda pop will become ____________________.

• A.

Cool

• B.

Released

• C.

Absorbs

• D.

Heat

A. Cool
Explanation
When an ice cube is placed in a glass of soda pop, the heat from the soda pop is transferred to the ice cube, causing it to melt. As the ice cube melts, it absorbs heat from the soda pop, resulting in a decrease in temperature. Therefore, the soda pop will become cool.

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• 16.

### Sweating makes you feel cooler because, as it evaporates, the water on your skin ____________________ heat from your body.

• A.

Cool

• B.

Released

• C.

Absorbs

• D.

Heat

C. Absorbs
Explanation
Sweating makes you feel cooler because, as it evaporates, the water on your skin absorbs heat from your body. When sweat evaporates, it takes the heat energy from your skin, resulting in a cooling effect. This is why sweating is a natural mechanism of the body to regulate its temperature and prevent overheating.

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• 17.

### A(n) ____________________ is a physical or chemical change that occurs with no outside intervention.

• A.

Spontaneous process

• B.

Law of disorder

• C.

Entropy

• D.

Free energy

A. Spontaneous process
Explanation
A spontaneous process refers to a physical or chemical change that occurs on its own without any external influence or intervention. It is a natural occurrence that happens without the need for any additional energy or force. This term is often used in thermodynamics to describe processes that happen without the input of work or heat. Spontaneous processes tend to move towards a state of lower energy or higher entropy, which is a measure of disorder in a system.

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• 18.

### ____________________ is the energy that is available to do work

• A.

Spontaneous process

• B.

Law of disorder

• C.

Entropy

• D.

Free energy

D. Free energy
Explanation
Free energy is the correct answer because it refers to the energy that is available to do work. It is the energy that can be utilized to perform useful tasks or drive chemical reactions. Free energy is a measure of the system's ability to do work and is related to both the system's internal energy and its entropy. In thermodynamics, it is often denoted as G and is used to determine whether a process is spontaneous or not. A negative value of free energy indicates a spontaneous process, while a positive value indicates a non-spontaneous process.

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• 19.

### The ____________________ states that spontaneous processes always proceed in such a way that the entropy of the universe increases.

• A.

Spontaneous process

• B.

Law of disorder

• C.

Entropy

• D.

Free energy

B. Law of disorder
Explanation
The law of disorder states that spontaneous processes always proceed in such a way that the entropy of the universe increases. Entropy is a measure of the disorder or randomness in a system, and the law of disorder states that in any spontaneous process, the overall disorder of the universe will increase. This means that the system will tend to move towards a state of greater randomness or chaos. The concept of entropy is closely related to the concept of free energy, which is the energy available to do work in a system. However, while free energy is a measure of the system's ability to do work, entropy is a measure of the system's disorder.

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• 20.

### A measure of disorder or randomness of the particles that make up a system is called ____________________.

• A.

Spontaneous process

• B.

Law of disorder

• C.

Entropy

• D.

Free energy

C. Entropy
Explanation
Entropy is a measure of disorder or randomness in a system. It quantifies the number of possible arrangements or states that the particles of a system can have. As the system becomes more disordered, its entropy increases. This concept is widely used in physics and chemistry to understand the behavior of systems and predict the direction of spontaneous processes. The other options, spontaneous process, law of disorder, and free energy, are not correct because they do not specifically refer to the measure of disorder or randomness in a system.

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• 21.

### Energy exits in two basic forms, ____________________ and ____________________ energy

• A.

Potential / kinetic

• B.

Exothermic / endothermic

• C.

Chemical

• D.

Universe

• E.

Standard

• F.

Same

A. Potential / kinetic
Explanation
Energy exits in two basic forms, potential and kinetic energy. Potential energy is the energy possessed by an object due to its position or condition, while kinetic energy is the energy possessed by an object due to its motion. These two forms of energy are fundamental in understanding the behavior and transformations of energy in various systems.

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• 22.

### The ____________________ enthalpy of formation is defined as the change in enthalpy that accompanies the formation of one mole of the compound in its standard state from its constituent elements in their standard states.

• A.

Potential / kinetic

• B.

Exothermic / endothermic

• C.

Chemical

• D.

Universe

• E.

Standard

• F.

Same

E. Standard
Explanation
The standard enthalpy of formation is defined as the change in enthalpy that accompanies the formation of one mole of the compound in its standard state from its constituent elements in their standard states. This means that it represents the enthalpy change when a compound is formed from its elements under specific conditions, such as a temperature of 298 K and a pressure of 1 bar. It is a measure of the stability of a compound and is commonly used in thermochemistry calculations.

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• 23.

### The ____________________ is defined as the system along with the surroundings.

• A.

Potential / kinetic

• B.

Exothermic / endothermic

• C.

Chemical

• D.

Universe

• E.

Standard

• F.

Same

D. Universe
Explanation
The term "universe" refers to the entirety of everything that exists, including all matter, energy, and space. In the context of the question, the universe is being described as the system along with the surroundings. This suggests that when considering a specific system, such as a chemical reaction or physical process, it is important to also consider the broader environment or surroundings in which the system exists. By including the concept of the universe, the answer emphasizes the need to take into account the larger context when analyzing a system.

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• 24.

### The energy stored in a substance due to its composition is called ____________________ potential energy.

• A.

Potential / kinetic

• B.

Exothermic / endothermic

• C.

Chemical

• D.

Universe

• E.

Standard

• F.

Same

C. Chemical
Explanation
Chemical potential energy refers to the energy stored in a substance due to its composition. This energy is a result of the arrangement of atoms and the chemical bonds between them. It can be released or absorbed during chemical reactions.

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• 25.

### The molar enthalpies of condensation and vaporization have the ____________________ numerical value

• A.

Potential / kinetic

• B.

Exothermic / endothermic

• C.

Chemical

• D.

Universe

• E.

Standard

• F.

Same

F. Same
Explanation
The molar enthalpies of condensation and vaporization have the same numerical value because they represent opposite processes of the same substance. Condensation is the process of a gas turning into a liquid, while vaporization is the process of a liquid turning into a gas. Both processes involve a change in enthalpy, but the magnitude of the change is the same in both cases. This is because the enthalpy change is determined by the strength of the intermolecular forces between the particles of the substance, which remain the same regardless of the direction of the phase change.

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• 26.

### An insulated device used to measure the amount of heat absorbed or released during a chemical or physical process

• A.

Calorimeter

• B.

Thermochemistry

• C.

System

• D.

Enthalpy (heat) of reaction

A. Calorimeter
Explanation
A calorimeter is an insulated device used to measure the amount of heat absorbed or released during a chemical or physical process. It is specifically designed to prevent any heat exchange with the surroundings, allowing for accurate measurement of the heat involved in a reaction. By measuring the temperature change of the substances inside the calorimeter, the heat transfer can be calculated using the principles of thermodynamics. This makes the calorimeter an essential tool in the field of thermochemistry, where the heat of reaction or enthalpy change is studied.

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• 27.

### The study of heat changes that accompany chemical reactions and phase changes

• A.

Calorimeter

• B.

Thermochemistry

• C.

System

• D.

Enthalpy (heat) of reaction

B. Thermochemistry
Explanation
Thermochemistry is the study of heat changes that occur during chemical reactions and phase changes. It involves measuring and calculating the amount of heat released or absorbed in a reaction. This field of study is important in understanding the energy changes that occur during chemical reactions and helps in determining the efficiency and feasibility of various processes.

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• 28.

### The specific part of the universe that contains the reaction or process you wish to study

• A.

Calorimeter

• B.

Thermochemistry

• C.

System

• D.

Enthalpy (heat) of reaction

C. System
Explanation
The term "system" refers to the specific part of the universe that contains the reaction or process being studied. In the context of this question, the system is the focus of the study, and the properties and changes within the system are being analyzed. The other options, such as calorimeter, thermochemistry, and enthalpy of reaction, are related concepts but do not specifically define the part of the universe being studied.

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• 29.

### The change in enthalpy in a chemical reaction

• A.

Calorimeter

• B.

Thermochemistry

• C.

System

• D.

Enthalpy (heat) of reaction

D. Enthalpy (heat) of reaction
Explanation
The correct answer is "enthalpy (heat) of reaction". Enthalpy of reaction refers to the change in heat energy during a chemical reaction. It is a measure of the amount of heat released or absorbed during the reaction. This term is commonly used in thermochemistry to quantify the energy changes in a system. A calorimeter is a device used to measure these energy changes by measuring the heat flow in or out of the system. Therefore, the enthalpy of reaction is the most appropriate term to describe the change in enthalpy in a chemical reaction.

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• 30.

### A system plus its surroundings

• A.

Universe

• B.

Enthalpy

• C.

Surroundings

• D.

Enthalpy (heat) of reaction

A. Universe
Explanation
The term "universe" refers to the combination of a system and its surroundings. In thermodynamics, a system is the specific portion of matter or space being studied, while the surroundings include everything outside of the system that can interact with it. The universe encompasses both the system and its surroundings, allowing for the analysis of energy and heat transfer between them. The concept of the universe is important in understanding thermodynamic processes and calculating properties such as enthalpy, which represents the heat content of a system.

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• 31.

### The heat content of a system at constant pressure

• A.

Universe

• B.

Enthalpy

• C.

Surroundings

• D.

Enthalpy (heat) of reaction

B. Enthalpy
Explanation
Enthalpy is the correct answer because it refers to the heat content of a system at constant pressure. It is a measure of the total energy of a system, including both its internal energy and the work done by or on the system. Enthalpy is often used to describe heat transfer in chemical reactions, as it represents the heat exchanged between the system and its surroundings.

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• 32.

### Everything in the universe except the system being studied

• A.

Universe

• B.

Enthalpy

• C.

Surroundings

• D.

Enthalpy (heat) of reaction

C. Surroundings
Explanation
The term "surroundings" refers to everything in the universe except the system being studied. In the context of the question, the surroundings would include all other elements, objects, and systems outside of the specific system under consideration. This could include the physical environment, other substances, and any external factors that may impact the system. The surroundings play a crucial role in determining the overall behavior and characteristics of the system, as they can exchange energy or matter with the system.

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• 33.

### The ability to do work or produce heat

• A.

Energy

• B.

Law of conservation of energy

• C.

Heat

• D.

Thermochemistry

• E.

Chemical potential energy

A. Energy
Explanation
Energy is the ability to do work or produce heat. It is a fundamental concept in physics and is essential for all forms of life and processes in the universe. The law of conservation of energy states that energy cannot be created or destroyed, only transformed from one form to another. Heat is a form of energy that is transferred between objects or systems due to temperature differences. Thermochemistry is the study of the energy changes that occur during chemical reactions. Chemical potential energy is a form of energy stored in the bonds of chemical substances.

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• 34.

### States that energy cannot be created or destroyed

• A.

Specific heat

• B.

Calorimeter

• C.

Universe

• D.

Law of disorder

• E.

Surroundings

• F.

Law of conservation of energy

F. Law of conservation of energy
Explanation
The law of conservation of energy states that energy cannot be created or destroyed. This means that the total amount of energy in a closed system remains constant over time. It can only be transferred or converted from one form to another. This principle is a fundamental concept in physics and is used to explain various phenomena, such as the behavior of heat and work in thermodynamics. It is also applicable to the universe as a whole, suggesting that the total energy content of the universe is constant.

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• 35.

### Energy flowing from a warmer to a cooler object

• A.

Energy

• B.

Law of conservation of energy

• C.

Heat

• D.

Thermochemistry

• E.

Chemical potential energy

C. Heat
Explanation
Heat is the correct answer because it refers to the transfer of energy from a warmer object to a cooler object. Heat is a form of energy that is transferred due to temperature differences between objects. It follows the law of conservation of energy, which states that energy cannot be created or destroyed, only transferred or transformed. Thermochemistry is the branch of chemistry that studies the heat energy involved in chemical reactions. Chemical potential energy refers to the energy stored in the bonds of chemical substances.

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• 36.

### The study of heat changes from chemical reactions and phase changes

• A.

Energy

• B.

Law of conservation of energy

• C.

Heat

• D.

Thermochemistry

• E.

Chemical potential energy

D. Thermochemistry
Explanation
Thermochemistry is the study of heat changes in chemical reactions and phase changes. It involves the measurement and calculation of the amount of heat energy involved in these processes. Thermochemistry is based on the law of conservation of energy, which states that energy cannot be created or destroyed, only transferred or converted from one form to another. Heat is a form of energy that is transferred during chemical reactions and phase changes, and thermochemistry helps to understand and quantify these heat changes. Therefore, thermochemistry is the correct answer in this context.

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• 37.

### Energy stored in a substance because of its composition

• A.

Energy

• B.

Law of conservation of energy

• C.

Heat

• D.

Thermochemistry

• E.

Chemical potential energy

E. Chemical potential energy
Explanation
Chemical potential energy refers to the energy that is stored within a substance due to its composition. This energy is released or absorbed during chemical reactions. It is a form of potential energy that is stored in the chemical bonds between atoms and molecules. When these bonds are broken or formed, energy is either released or absorbed. This concept is a fundamental principle in thermochemistry, which is the study of the energy changes that occur during chemical reactions. The answer choice "chemical potential energy" accurately describes the energy stored in a substance due to its composition.

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• 38.

### Heat required to raise the temperature of one gram of a substance by one degree Celsius

• A.

Energy

• B.

Law of conservation of energy

• C.

Heat

• D.

Thermochemistry

• E.

Chemical potential energy

• F.

Specific heat

F. Specific heat
Explanation
Specific heat is the correct answer because it refers to the amount of heat energy required to raise the temperature of one gram of a substance by one degree Celsius. It is a characteristic property of a substance and is used in thermochemistry to calculate the amount of heat exchanged during a chemical reaction or a change in temperature. The specific heat value varies for different substances and is an important factor in understanding their thermal properties.

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• 39.

### An insulated device measuring the heat absorbed or released during a chemical or physical process

• A.

Enthalpy (heat) of reaction

• B.

Thermochemical equation

• C.

Universe

• D.

Enthalpy

• E.

Molar enthalpy (heat) of vaporization

• F.

Calorimeter

F. Calorimeter
Explanation
A calorimeter is an insulated device used to measure the heat absorbed or released during a chemical or physical process. It is commonly used to determine the enthalpy (heat) of reaction or the molar enthalpy (heat) of vaporization. The calorimeter prevents heat exchange with the surroundings, allowing for accurate measurement of the heat involved in a reaction.

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• 40.

### The system plus the surroundings

• A.

Specific heat

• B.

Calorimeter

• C.

Universe

• D.

Law of disorder

• E.

Surroundings

C. Universe
Explanation
The term "universe" refers to the entire system and surroundings being considered in a given context. In the context of this question, the universe represents the combination of the system and its surroundings.

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• 41.

### States that spontaneous processes always proceed in such a way that the entropy of the universe increases

• A.

Specific heat

• B.

Calorimeter

• C.

Universe

• D.

Law of disorder

• E.

Surroundings

D. Law of disorder
Explanation
The given correct answer is "law of disorder." This law, also known as the second law of thermodynamics, states that spontaneous processes always proceed in a way that the entropy of the universe increases. Entropy is a measure of the disorder or randomness in a system. According to this law, in any spontaneous process, the overall disorder of the universe will always increase. This is because the energy and matter tend to disperse and become more evenly distributed, resulting in an increase in entropy.

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• 42.

### Everything in the universe other than the system

• A.

Specific heat

• B.

Calorimeter

• C.

Universe

• D.

Law of disorder

• E.

Surroundings

E. Surroundings
Explanation
The term "surroundings" refers to everything in the universe other than the system. In the context of the question, the surroundings are mentioned alongside specific heat, calorimeter, universe, and the law of disorder. This suggests that the correct answer is "surroundings" because it is related to the other terms mentioned and is the only option that encompasses everything outside of the system.

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• 43.

### The change in enthalpy in a chemical reaction

• A.

Specific heat

• B.

Calorimeter

• C.

Universe

• D.

Law of disorder

• E.

Surroundings

• F.

Enthalpy (heat) of reaction

F. Enthalpy (heat) of reaction
Explanation
The change in enthalpy in a chemical reaction refers to the heat released or absorbed during the reaction. Enthalpy is a measure of the energy content of a system, and the change in enthalpy indicates the difference in energy between the reactants and the products. This change in enthalpy, also known as the heat of reaction, can be measured using a calorimeter. It is important to note that the change in enthalpy of a reaction is influenced by the surroundings and follows the law of disorder, which states that the entropy of the universe tends to increase.

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• 44.

### A balanced chemical equation that includes the physical states of all reactants and products and the energy change that accompanies the reaction

• A.

Standard enthalpy (heat) of formation

• B.

Molar enthalpy (heat) of fusion

• C.

Spontaneous process

• D.

Enthalpy (heat) of combustion

• E.

Free energy

• F.

Joule

• G.

Thermochemical equation

G. Thermochemical equation
Explanation
A thermochemical equation is a balanced chemical equation that includes the physical states of all reactants and products and the energy change that accompanies the reaction. It provides information about the heat energy involved in a chemical reaction. This type of equation is used to calculate the enthalpy (heat) change of a reaction, which is important in understanding the energy transformations that occur during chemical reactions.

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• 45.

### A system’s heat content at constant pressure

• A.

Enthalpy (heat) of reaction

• B.

Thermochemical equation

• C.

Universe

• D.

Enthalpy

• E.

Molar enthalpy (heat) of vaporization

D. Enthalpy
Explanation
Enthalpy is a measure of the heat content of a system at constant pressure. It is a thermodynamic property that describes the total energy of a system, including both its internal energy and the energy required to overcome the pressure-volume work. In the context of the given options, enthalpy is the most appropriate term to describe the system's heat content at constant pressure. The other options, such as the enthalpy of reaction or molar enthalpy of vaporization, are specific types of enthalpy that describe heat changes in certain chemical reactions or phase changes, but they do not encompass the overall heat content of the system.

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• 46.

### Energy required to vaporize one mole of a liquid

• A.

Enthalpy (heat) of reaction

• B.

Thermochemical equation

• C.

Universe

• D.

Enthalpy

• E.

Molar enthalpy (heat) of vaporization

E. Molar enthalpy (heat) of vaporization
Explanation
The molar enthalpy (heat) of vaporization refers to the amount of energy required to convert one mole of a liquid substance into its gaseous state at a constant temperature and pressure. It is a measure of the strength of the intermolecular forces holding the liquid molecules together. The higher the molar enthalpy of vaporization, the stronger the intermolecular forces and the more energy required to break them and convert the liquid into a gas.

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• 47.

### Enthalpy change occurring when one mole of a compound in its standard state forms from its constituent elements in their standard states

• A.

Enthalpy (heat) of reaction

• B.

Thermochemical equation

• C.

Universe

• D.

Enthalpy

• E.

Molar enthalpy (heat) of vaporization

• F.

Standard enthalpy (heat) of formation

F. Standard enthalpy (heat) of formation
Explanation
The correct answer is "standard enthalpy (heat) of formation." This term refers to the enthalpy change that occurs when one mole of a compound in its standard state is formed from its constituent elements in their standard states. It is a measure of the energy released or absorbed during the formation of a compound.

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• 48.

### Energy required to melt one mole of a solid

• A.

Standard enthalpy (heat) of formation

• B.

Molar enthalpy (heat) of fusion

• C.

Spontaneous process

• D.

Enthalpy (heat) of combustion

• E.

Free energy

• F.

Joule

B. Molar enthalpy (heat) of fusion
Explanation
The molar enthalpy (heat) of fusion refers to the amount of energy required to melt one mole of a solid. This means that it measures the heat absorbed or released when a solid substance changes into its liquid phase at a constant temperature. It is a specific type of enthalpy change and is different from other enthalpy changes such as the enthalpy of formation or combustion. The molar enthalpy of fusion is specific to the substance being melted and is a characteristic property of that substance.

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• 49.

### A physical or chemical change without outside intervention

• A.

Standard enthalpy (heat) of formation

• B.

Molar enthalpy (heat) of fusion

• C.

Spontaneous process

• D.

Enthalpy (heat) of combustion

• E.

Free energy

• F.

Joule

C. Spontaneous process
Explanation
A spontaneous process refers to a physical or chemical change that occurs without any external intervention. It happens naturally and does not require any additional energy input. This means that the process can occur on its own, driven by the inherent tendencies of the system. It is important to note that a spontaneous process does not necessarily mean that it occurs quickly or instantaneously, but rather that it will occur without any external influence.

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• 50.

### The enthalpy change for the complete burning of one mole of a substance

• A.

Spontaneous process

• B.

Enthalpy (heat) of combustion

• C.

Free energy

• D.

Joule

• E.

Standard enthalpy (heat) of formation

• F.

Molar enthalpy (heat) of fusion

B. Enthalpy (heat) of combustion
Explanation
The correct answer is enthalpy (heat) of combustion. The enthalpy change for the complete burning of one mole of a substance refers to the amount of heat released or absorbed when one mole of a substance undergoes complete combustion in excess oxygen. It is a measure of the energy content of the substance and is commonly used to determine the heat released during combustion reactions.

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• Current Version
• Mar 20, 2023
Quiz Edited by
ProProfs Editorial Team
• Dec 09, 2014
Quiz Created by
Philip Baker

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