Chemistry 121 Chapter 5 Part 1
Study for chemistry test
Questions and Answers
- 1.
The study of the heat associated with chemical reactions and physical processes
- A.
State Function
- B.
Thermochemistry
- C.
Chemical Energy
Correct Answer
B. ThermochemistryExplanation
Thermochemistry is the study of the heat associated with chemical reactions and physical processes. It focuses on the energy changes that occur during these reactions and processes. Thermochemistry helps us understand how energy is transferred and transformed within a system. It also allows us to calculate and predict the heat changes that occur in various reactions, which is essential in fields such as chemical engineering and materials science. Therefore, Thermochemistry is the correct answer for this question.Rate this question:
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- 2.
One that can exchange energy to the surroundings freely
- A.
Open Systems
- B.
Closed System
- C.
Isolated
Correct Answer
A. Open SystemsExplanation
Open systems are able to exchange energy with their surroundings freely. This means that energy can flow in and out of the system, allowing it to interact and respond to changes in its environment. In contrast, closed systems do not exchange energy with the surroundings, while isolated systems do not exchange energy or matter. Therefore, an open system is the correct answer because it describes a system that can freely exchange energy with its surroundings.Rate this question:
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- 3.
Allows energy to escape but not the mass
- A.
Open Systems
- B.
Isolated
- C.
Closed System
Correct Answer
C. Closed SystemExplanation
A closed system is a type of system that allows energy to escape but not the mass. In a closed system, there is no exchange of matter with the surroundings, but energy can be transferred in or out of the system. This means that while the system remains isolated from its surroundings in terms of mass, it can still interact with its surroundings through energy transfer.Rate this question:
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- 4.
Allows nothing to transfer between the system and the surroundings
- A.
Open Systems
- B.
Isolated
- C.
Closed System
Correct Answer
B. IsolatedExplanation
An isolated system is one that does not allow anything to transfer between the system and the surroundings. This means that no matter or energy can enter or leave the system, making it completely closed off from its surroundings. In contrast, an open system allows for the transfer of both matter and energy, while a closed system only allows for the transfer of energy. Therefore, the correct answer is "Isolated."Rate this question:
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- 5.
The ability to do work
- A.
Joules
- B.
State Function
- C.
Energy
Correct Answer
C. EnergyExplanation
Energy is the correct answer because it refers to the ability to do work. Energy is a fundamental concept in physics and is defined as the capacity to cause change or perform work. It exists in various forms such as kinetic energy, potential energy, thermal energy, etc. The unit of energy is Joules, which measures the amount of work done or energy transferred. Energy is considered a state function because it depends only on the initial and final states of a system, regardless of the path taken to reach those states.Rate this question:
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- 6.
The energy that is stored in the structural units of the chemical substances
- A.
Calorimetry
- B.
Chemical Energy
- C.
Enthalpy (H)
Correct Answer
B. Chemical EnergyExplanation
Chemical energy refers to the energy that is stored within the structural units of chemical substances. It is a form of potential energy that can be released through chemical reactions. Calorimetry is a technique used to measure the heat energy involved in chemical reactions, while enthalpy (H) is a thermodynamic property that represents the total heat content of a system. Therefore, the correct answer, chemical energy, aligns with the concept of energy stored in the structural units of chemical substances.Rate this question:
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- 7.
Gives out heat and transfers heat energy to the surroundings. Theses heat values are always negative
- A.
Endothermic
- B.
Bond Energy
- C.
Exothermic
Correct Answer
C. ExothermicExplanation
Exothermic reactions release heat energy to the surroundings, resulting in a decrease in the system's internal energy. This can be observed by a rise in temperature in the surroundings. The statement "Gives out heat and transfers heat energy to the surroundings" aligns with the definition of an exothermic reaction. Additionally, the mention of "negative heat values" further supports this, as exothermic reactions are typically associated with negative enthalpy values. Therefore, the correct answer is Exothermic.Rate this question:
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- 8.
Chemical reaction that takes in heat from the surroundings. These heat values are always positive
- A.
Endothermic
- B.
Exothermic
- C.
Chemical Energy
Correct Answer
A. EndothermicExplanation
Endothermic reactions are characterized by the absorption of heat from the surroundings. In these reactions, the products have higher energy than the reactants, and the difference is gained from the surroundings as heat. This is why the heat values for endothermic reactions are always positive.Rate this question:
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- 9.
The unit of measure used for measuring energy changes
- A.
Joules
- B.
Enthalpy Change
- C.
Thermochemistry
Correct Answer
A. JoulesExplanation
Joules is the correct answer because it is the standard unit of measure used for measuring energy changes. In the context of thermodynamics and thermochemistry, energy changes are often expressed in terms of joules. Enthalpy change, on the other hand, is a specific type of energy change that represents the heat transferred in a chemical reaction at constant pressure. While enthalpy change is related to energy changes, it is not the general unit of measure for all energy changes.Rate this question:
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- 10.
Properties that are determined by the state of the system, regardless of how that condition was achieved
- A.
Hess’s Law
- B.
Closed System
- C.
State Function
Correct Answer
C. State FunctionExplanation
A state function refers to a property of a system that is solely determined by its current state, regardless of how that state was achieved. This means that the value of the state function depends only on the current conditions of the system, such as its temperature, pressure, or volume, and not on the path or history of how the system reached that state. In other words, state functions are independent of the process or pathway followed to reach a particular state.Rate this question:
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- 11.
Used to quantify the heat flow into or out of a system in a process that occurs at constant P, V.
- A.
Enthalpy Change
- B.
Enthalpy (H)
- C.
Endothermic
Correct Answer
B. Enthalpy (H)Explanation
Enthalpy (H) is the correct answer because it is a thermodynamic property that quantifies the heat flow into or out of a system at constant pressure and volume. It represents the total energy of a system, including its internal energy and the energy associated with the pressure-volume work done on or by the system. Enthalpy change is often used to describe the heat transfer in chemical reactions or phase changes.Rate this question:
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- 12.
The measurement of heat changes.
- A.
Calorimetry
- B.
Joules
- C.
State Function
Correct Answer
A. CalorimetryExplanation
Calorimetry is the correct answer because it is the branch of science that deals with the measurement of heat changes. It involves using a calorimeter to measure the amount of heat absorbed or released during a chemical or physical process. Calorimetry is important in various fields, such as chemistry and thermodynamics, as it allows scientists to study and understand the energy changes that occur in different systems.Rate this question:
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- 13.
The value of energy needed to break a bond
- A.
Enthalpy Change
- B.
Energy
- C.
Bond Energy
Correct Answer
C. Bond EnergyExplanation
Bond energy refers to the amount of energy required to break a chemical bond. It is the measure of the strength of a bond, and the higher the bond energy, the stronger the bond. When a bond is broken, energy is absorbed, and when a bond is formed, energy is released. Therefore, bond energy is a measure of the energy change that occurs during a chemical reaction. It is an important concept in understanding the stability and reactivity of molecules.Rate this question:
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- 14.
The difference in energy between product and reactant
- A.
Thermochemistry
- B.
Enthalpy Change
- C.
State Function
Correct Answer
B. Enthalpy ChangeExplanation
Enthalpy change refers to the difference in energy between the products and reactants in a chemical reaction. It is a measure of the heat energy released or absorbed during a reaction. Enthalpy change is a fundamental concept in thermochemistry and is a state function, meaning it only depends on the initial and final states of the system, not on the path taken to reach those states.Rate this question:
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- 15.
It takes energy to break bonds, and energy is given back when bonds are made
- A.
Energy, taken
- B.
Energy, given back
- C.
Calorimetry, given back
Correct Answer
B. Energy, given backExplanation
When bonds are broken, energy is required to break the bonds. This is because breaking bonds involves overcoming the attractive forces between atoms or molecules. On the other hand, when new bonds are formed, energy is released. This is because the formation of bonds involves the formation of new attractive forces between atoms or molecules. Therefore, the statement "energy is given back when bonds are made" is a correct explanation of the relationship between energy and bond formation.Rate this question:
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- 16.
When reactants are converted to products, the enthalpy of the reaction is the same, no matter if it occurs in one step or a series of steps
- A.
Hess’s Law
- B.
Calorimetry
- C.
Enthalpy (H)
Correct Answer
A. Hess’s LawExplanation
Hess's Law states that the overall enthalpy change of a reaction is independent of the pathway taken to reach the final products. This means that whether a reaction occurs in one step or a series of steps, the total enthalpy change will be the same. This principle is useful in determining the enthalpy change of a reaction by combining known enthalpy changes of other reactions. Calorimetry is the experimental technique used to measure the heat changes in a reaction, while enthalpy (H) is a thermodynamic property that represents the heat content of a system.Rate this question:
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