CHEM120 FINAL STUDY SHEET 2026 FULL
QUESTIONS WITH SOLUTIONS GRADED A+
⩥Which of these processes would not be possible? Answer: Energy
cannot be created or destroyed in a chemical reaction.
⩥Energy and First Law of Thermodynamics. Answer: 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 goes 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.
⩥The Second Law of Thermodynamics. Answer: The second law of
thermodynamics tells us about how energy in the universe behaves in
terms of flow and organization.
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.
⩥As a rocket takes off, energy in the fuel is converted into kinetic
energy, heat, and light.. Answer: 1st law of thermodynamics
⩥An ice cube melts on a hot day.. Answer: 2nd law of thermodynamics
⩥On a hot day, you turn on the oven, causing the room to become even
hotter.. Answer: 2nd law of thermodynamics
⩥Turning on a computer results in electricity being converted into
mechanical work, heat, and light.. Answer: 1st law of thermodynamics
⩥Endothermic and Exothermic Reactions. Answer: 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)
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.
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.
⩥Endothermic Reactions:
QUESTIONS WITH SOLUTIONS GRADED A+
⩥Which of these processes would not be possible? Answer: Energy
cannot be created or destroyed in a chemical reaction.
⩥Energy and First Law of Thermodynamics. Answer: 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 goes 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.
⩥The Second Law of Thermodynamics. Answer: The second law of
thermodynamics tells us about how energy in the universe behaves in
terms of flow and organization.
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.
⩥As a rocket takes off, energy in the fuel is converted into kinetic
energy, heat, and light.. Answer: 1st law of thermodynamics
⩥An ice cube melts on a hot day.. Answer: 2nd law of thermodynamics
⩥On a hot day, you turn on the oven, causing the room to become even
hotter.. Answer: 2nd law of thermodynamics
⩥Turning on a computer results in electricity being converted into
mechanical work, heat, and light.. Answer: 1st law of thermodynamics
⩥Endothermic and Exothermic Reactions. Answer: 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)
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.
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.
⩥Endothermic Reactions:
