CONCEPT SUMMARY
CONCEPT SUMMARY OF THERMODYNAMICS
WITH ANSWERED POSSIBLE QUESTIONS
LAWS OF THERMODYNAMICS
In this section, we explore the rules of energy that we observe in the
universe. We see many examples of these laws in action on a day-to-
day basis. You will learn how to compare and contrast exothermic
and endothermic reactions as well as the first and second laws of
thermodynamics.
1. Which of these would you classify as an exothermic process?
o Evaporation of alcohol o Photosynthesis o Wood burning o Ice melting
2. Which one of these processes would NOT be possible?
o Energy is transferred in a chemical reaction o Energy is created in a chemical
reaction
o Two liquid chemicals are mixed together, and the temperature of the mixture rapidly
cools o Energy spontaneously flows from a hot object
Energy cannot be created or destroyed in a chemical reaction.
ENERGY AND FIRST LAW OF THERMODYNAMICS
Energy takes many forms. A few of the more common forms of energy we observe are light, heat,
mechanical energy, and electricity. Energy is the driving force of this universe and necessary for all
life, light, and movement. Energy can be measured using various units, including calories and joules.
A good starting point in understanding the flow of energy is the First Law of Thermodynamics:
Energy in an isolated system cannot be created or destroyed, only transferred.
This law is often also known as Conservation of Energy, as this law tells us that energy is conserved and
simply moved from one place to another and one form to another. For example, when you drive a car
down the road, you are converting the chemical energy found in gasoline into heat and kinetic
(movement) energy. None of this energy is destroyed or eliminated in this process.
As another example of the first law of thermodynamics in action consider a falling stone hitting the
earth. The kinetic energy of this stone is converted mainly into sound, and vibration. In both of
these examples, we see that energy can move from one form to another.
You may have noticed the term “isolated system” in the 1st Law of Thermodynamics. This term means a
system where no matter and no energy go into or out of the system. Our universe, as we understand it,
is an example of such a system, so this law applies to our universe.
,CONCEPT SUMMARY
SECOND LAW OF THERMODYNAMICS
The second law of thermodynamics tells us about how energy in the universe
behaves in terms of flow and organization.
,CONCEPT SUMMARY
The amount of entropy in an isolated system irreversibly increases over time.
This law tells us that the amount of entropy, or disorder, in the universe is constantly increasing. An
important reason for this is that heat spontaneously and irreversibly transfers from a hot body to a cold
body. An example that illustrates both of these points is a cup of hot coffee sitting outside on a cold
winter's day. At first, the heat is localized into the area of the liquid in the cup; however, the heat quickly
begins to disperse into the surrounding environment spontaneously. Over time, the coffee in the cup will
have the same temperature as the surrounding environment as the temperatures even out. In this way,
we see that:
• Heat was spontaneously and irreversibly transferred from a higher temperature system area to
the lower temperature surroundings.
• Disorder increased as the localized heat spread through the surroundings.
3. For each of the situations, determine if the observed behavior is a consequence of the first or second
Law of Thermodynamics:
Situation Select Law
As a rocket takes off, energy in the fuel is converted into kinetic 1st Law of
energy, heat, and light. Thermodynamics
An ice cube melts on a hot day. 2nd Law of
Thermodynamics
On a hot day, you turn on the oven, causing the room to become 2nd Law of
even hotter. Thermodynamics
Turning on a computer results in electricity being converted into
1st Law of Thermodynamics
mechanical work, heat, and light.
ENDOTHERMIC AND EXOTHERMIC REACTIONS
Energy can flow into a system from the surroundings or from the
surroundings into the system. The terminology we use for these
processes is:
• Exothermic: Energy from system to surroundings (energy
released)
• Endothermic: Energy from surroundings to system
(Energy absorbed)
The image illustrates this process. We often measure this energy
in the form of heat, so heat flowing from the system to the surroundings is considered exothermic,
while heat flowing into the system is considered endothermic. A good mnemonic is that exo = exit
(energy exits).
An example of an exothermic process is a burning match. The burning match releases heat into the
surroundings and is thus classified as exothermic. On the other hand, you may have used a chemical
cooling pack to treat an injury. In a chemical cooling pack, the chemical reaction absorbs heat from
the surroundings, cooling your injury. Since energy is going from the surroundings to the system, we
would consider this process endothermic.
, CONCEPT SUMMARY
What about ice melting? Would you consider this to be endothermic or exothermic? Is energy going in,
or is energy going out?
Ice melting is endothermic as energy goes into the ice, giving the molecules of water the energy they
need to move more quickly. This transforms the solid. As a material absorbs energy (endothermic), the
atoms and molecules in the material move more quickly and the state of the material changes from
solid to liquid to gas. Opposingly, as a material releases energy (exothermic), the atoms and molecules
slow down, moving from gas to liquid to solid.
4. Match the reaction to the type:
o Endothermic
o Photosynthesis o Chemical ice packs o Methanol evaporating o
Iron melting o Exothermic
o Water freezing o Burning gasoline
o Water condensing on a cool surface
o Two chemicals are mixed together, producing heat
5. When a cool penny is placed in a hot car in the summer, the heat flows spontaneously from the
interior of the car to the penny in an illustration of the 2nd Law of thermodynamics.
6. Sort the following process as exothermic or endothermic:
o Endothermic:
o A pair of chemicals are mixed together in a beaker and the beaker
becomes cold o Carbon dioxide converts from a solid to a gas o
Exothermic:
o Your body digests food for energy, generating excess heat o On a
humid day water condenses on a cool surface o Wood burns in a
bonfire
7. When sodium hydroxide is dissolved in water within a beaker, you observe that the beaker becomes
warm. This situation illustrates:
o The 2nd Law of Thermodynamics o
The 1st Law of Thermodynamics o An
Exothermic reaction
8. Select all the following situations that you would classify as endothermic processes:
o Ammonium nitrate dissolves in water and the solution becomes cold
o Lava cools and becomes a solid o Butane combusts to give a flame in a
lighter o Hand sanitizer evaporating
RADIATION
When we hear the word radiation, often our minds turn to power plants, nuclear weapons, and
reactors. In fact, radiation is so much more and has been part of our universe from the very beginning.
In this lesson, we will explore the concept of radiation and the types of radiation that we encounter.
9. Which of the following are types of electromagnetic radiation?
o X-rays o Alpha particles o
o
Ligh
10. Which type of radiation would you consider ionizing radiation?
t
o Visible light
Radio
o Microwaves o Gamma rays o Sound
waves
waves
11. Which of the following procedures in healthcare involve the use of radiation to take images?
CONCEPT SUMMARY OF THERMODYNAMICS
WITH ANSWERED POSSIBLE QUESTIONS
LAWS OF THERMODYNAMICS
In this section, we explore the rules of energy that we observe in the
universe. We see many examples of these laws in action on a day-to-
day basis. You will learn how to compare and contrast exothermic
and endothermic reactions as well as the first and second laws of
thermodynamics.
1. Which of these would you classify as an exothermic process?
o Evaporation of alcohol o Photosynthesis o Wood burning o Ice melting
2. Which one of these processes would NOT be possible?
o Energy is transferred in a chemical reaction o Energy is created in a chemical
reaction
o Two liquid chemicals are mixed together, and the temperature of the mixture rapidly
cools o Energy spontaneously flows from a hot object
Energy cannot be created or destroyed in a chemical reaction.
ENERGY AND FIRST LAW OF THERMODYNAMICS
Energy takes many forms. A few of the more common forms of energy we observe are light, heat,
mechanical energy, and electricity. Energy is the driving force of this universe and necessary for all
life, light, and movement. Energy can be measured using various units, including calories and joules.
A good starting point in understanding the flow of energy is the First Law of Thermodynamics:
Energy in an isolated system cannot be created or destroyed, only transferred.
This law is often also known as Conservation of Energy, as this law tells us that energy is conserved and
simply moved from one place to another and one form to another. For example, when you drive a car
down the road, you are converting the chemical energy found in gasoline into heat and kinetic
(movement) energy. None of this energy is destroyed or eliminated in this process.
As another example of the first law of thermodynamics in action consider a falling stone hitting the
earth. The kinetic energy of this stone is converted mainly into sound, and vibration. In both of
these examples, we see that energy can move from one form to another.
You may have noticed the term “isolated system” in the 1st Law of Thermodynamics. This term means a
system where no matter and no energy go into or out of the system. Our universe, as we understand it,
is an example of such a system, so this law applies to our universe.
,CONCEPT SUMMARY
SECOND LAW OF THERMODYNAMICS
The second law of thermodynamics tells us about how energy in the universe
behaves in terms of flow and organization.
,CONCEPT SUMMARY
The amount of entropy in an isolated system irreversibly increases over time.
This law tells us that the amount of entropy, or disorder, in the universe is constantly increasing. An
important reason for this is that heat spontaneously and irreversibly transfers from a hot body to a cold
body. An example that illustrates both of these points is a cup of hot coffee sitting outside on a cold
winter's day. At first, the heat is localized into the area of the liquid in the cup; however, the heat quickly
begins to disperse into the surrounding environment spontaneously. Over time, the coffee in the cup will
have the same temperature as the surrounding environment as the temperatures even out. In this way,
we see that:
• Heat was spontaneously and irreversibly transferred from a higher temperature system area to
the lower temperature surroundings.
• Disorder increased as the localized heat spread through the surroundings.
3. For each of the situations, determine if the observed behavior is a consequence of the first or second
Law of Thermodynamics:
Situation Select Law
As a rocket takes off, energy in the fuel is converted into kinetic 1st Law of
energy, heat, and light. Thermodynamics
An ice cube melts on a hot day. 2nd Law of
Thermodynamics
On a hot day, you turn on the oven, causing the room to become 2nd Law of
even hotter. Thermodynamics
Turning on a computer results in electricity being converted into
1st Law of Thermodynamics
mechanical work, heat, and light.
ENDOTHERMIC AND EXOTHERMIC REACTIONS
Energy can flow into a system from the surroundings or from the
surroundings into the system. The terminology we use for these
processes is:
• Exothermic: Energy from system to surroundings (energy
released)
• Endothermic: Energy from surroundings to system
(Energy absorbed)
The image illustrates this process. We often measure this energy
in the form of heat, so heat flowing from the system to the surroundings is considered exothermic,
while heat flowing into the system is considered endothermic. A good mnemonic is that exo = exit
(energy exits).
An example of an exothermic process is a burning match. The burning match releases heat into the
surroundings and is thus classified as exothermic. On the other hand, you may have used a chemical
cooling pack to treat an injury. In a chemical cooling pack, the chemical reaction absorbs heat from
the surroundings, cooling your injury. Since energy is going from the surroundings to the system, we
would consider this process endothermic.
, CONCEPT SUMMARY
What about ice melting? Would you consider this to be endothermic or exothermic? Is energy going in,
or is energy going out?
Ice melting is endothermic as energy goes into the ice, giving the molecules of water the energy they
need to move more quickly. This transforms the solid. As a material absorbs energy (endothermic), the
atoms and molecules in the material move more quickly and the state of the material changes from
solid to liquid to gas. Opposingly, as a material releases energy (exothermic), the atoms and molecules
slow down, moving from gas to liquid to solid.
4. Match the reaction to the type:
o Endothermic
o Photosynthesis o Chemical ice packs o Methanol evaporating o
Iron melting o Exothermic
o Water freezing o Burning gasoline
o Water condensing on a cool surface
o Two chemicals are mixed together, producing heat
5. When a cool penny is placed in a hot car in the summer, the heat flows spontaneously from the
interior of the car to the penny in an illustration of the 2nd Law of thermodynamics.
6. Sort the following process as exothermic or endothermic:
o Endothermic:
o A pair of chemicals are mixed together in a beaker and the beaker
becomes cold o Carbon dioxide converts from a solid to a gas o
Exothermic:
o Your body digests food for energy, generating excess heat o On a
humid day water condenses on a cool surface o Wood burns in a
bonfire
7. When sodium hydroxide is dissolved in water within a beaker, you observe that the beaker becomes
warm. This situation illustrates:
o The 2nd Law of Thermodynamics o
The 1st Law of Thermodynamics o An
Exothermic reaction
8. Select all the following situations that you would classify as endothermic processes:
o Ammonium nitrate dissolves in water and the solution becomes cold
o Lava cools and becomes a solid o Butane combusts to give a flame in a
lighter o Hand sanitizer evaporating
RADIATION
When we hear the word radiation, often our minds turn to power plants, nuclear weapons, and
reactors. In fact, radiation is so much more and has been part of our universe from the very beginning.
In this lesson, we will explore the concept of radiation and the types of radiation that we encounter.
9. Which of the following are types of electromagnetic radiation?
o X-rays o Alpha particles o
o
Ligh
10. Which type of radiation would you consider ionizing radiation?
t
o Visible light
Radio
o Microwaves o Gamma rays o Sound
waves
waves
11. Which of the following procedures in healthcare involve the use of radiation to take images?
