Download psaa specific heat worksheet

SPECIFIC HEAT
Student Learning Objectives. Instruction in this lesson should result in
students achieving the following objectives:
1 Explain the Kinetic Molecular Theory.
2 Describe the three mechanisms of heat transfer.
3 Identify the sources of thermal energy.
4 Justify the advantage of solids compared to liquids or gases as a conductor.
Anticipated Problem: What is the Kinetic Molecular Theory?
I. Kinetic theory is based on the idea that particles of matter are always in motion and that
this motion has consequences. The kinetic theory applies to solids, liquids, and gases.
A. Kinetic-Molecular Theory provides an explanation for heat and temperature. Matter is
composed of particles called molecules (atoms) which are in continuous motion. Heat
results from the motion of the molecules.
B. The kinetic molecule theory explains the forces between molecules and the energy that
they possess. This theory has 3 basic assumptions.
1. Matter is composed of small particles (molecules).
2. The measure of space that the molecules occupy (volume) is derived from the space
in between the molecules and not the space the molecules contain themselves.
3. The molecules are in constant motion. This motion is different for the 3 states of
matter.
a. Solid—molecules are held close to each other by their attractions of charge.
They will bend and/or vibrate, but will stay in close proximity.
b. Liquid—molecules will flow or glide over one another, but stay toward the bottom
of the container. Motion is a bit more random than that of a solid.
c. Gas—molecules are the continual straight line motion. The kinetic energy of
the molecule is greater than the attractive force between them, thus they are
much farther apart and move freely of each other.
C. When the molecules collide with each other, or with the walls of a container, there is
no loss of energy. Heat results from the motion of these molecules.
D. Temperature is a measure of the average kinetic energy of the molecules of a
substance. As molecules move faster the temperature of a substance increases.
Anticipated Problem: What are the three mechanisms of heat transfer?
II. The three mechanisms of heat transfer are conduction, convection, and radiation.
A. Conduction is the transfer of heat by direct contact. This is the simplest method of
heat transfer. A metal pan put directly above a hot burner is heated by conduction.
1. Which is a better conductor, tinfoil or Styrofoam? What are other examples of
conduction? In the northern latitudes, the oceans are warmer in summer than they are
in winter.
2. In which season do the oceans lose heat most rapidly to the atmosphere by conduction?
Explain.
B. Convection is the transfer of heat by movement of the heated part of a gas or liquid.
1. Heat transfer by convection can take place only in gases or liquids.
2. When a gas such as air or a liquid such as water is heated unevenly, the heated part
rises. This is an example of convection.
C. Radiation is transfer of heat through space by infrared rays. This heat transfer does not
cause particles of matter to move.
1. The earth receives heat energy from the sun by radiation. You feel warm while sitting
in the sun because you are receiving heat from the sun by radiation.
D. Using the three mechanisms of heat transfer that we just discussed, show with a
diagram how a thunderstorm can form.
Anticipated Problem: What are the sources of thermal energy?
III. Temperature is a description of a condition, a measure of the average kinetic energy
of the particles in a sample matter. Temperature indicates how hot or how cold something
is. The greater the kinetic energy of the particles in a sample of matter, the higher the
temperature of the matter is.
A. Heat is the sum total of the kinetic energies of the particles in a sample of matter. Heat
always flows spontaneously from matter at a higher temperature to matter at a lower
temperature.
B. To illustrate the difference between temperature and heat, consider a bathtub full of
warm water and a cup of boiling water
1. The temperature of the water in the tub is lower than that of the water in the cup.
2. Although the kinetic energy of each particle in the cup is greater than that of each
particle in the tub, the total heat energy in the tub will be much greater than that in
the cup, which has few particles.
C. Law of Thermodynamics—heat may not be created or destroyed; it will result from
the conversion of another form of energy. When two bodies are in contact, heat will flow
from a warm body to a cold body until they are at equal temperatures.
D. The heat required to raising one pound of substance one degree Fahrenheit or one
gram of a substance one degree Celsius is known as specific heat.
1. Materials vary in their ability to absorb and exchange heat. This information is
important to know when choosing materials for internal combustion engine components.
2. Heat must be contained and dissipated during operation.
E. Latent heat is the amount of heat needed to bring about a change of state. About 80
calories of latent heat are needed to change one gram of ice at zero degrees Celsius to
water at zero degrees Celsius.
F. Calorimetry deals with losses and gains of heat. A calorimeter is used to measure the
amount of heat lost by an object through transfer to a liquid, generally water.
1. The calorimeter is specially designed so that minimum of heat is lost to its
surroundings. Heat gain or loss is reflected in a change of temperature.
2. The amount of heat needed to raise the temperature of a substance a certain amount
when compared to the amount of heat needed to raise an equal amount of water the
same number of degrees is called specific heat.
3. A calorie is the amount of heat need to raise one gram of water one degree Celsius.
Anticipated Problem: Why are solids generally better conductors than liquids or gases?
IV. Solids are generally better conductors than liquids or gases because the molecules are
closer together.
A. Most metals, such as aluminum and copper, are good heat conductors. Other materials,
such as wool, straw, paper, cork, and wood are not good conductors of heat.
B. This is because most metallic elements are denser than cork, wood, or other nonconductors, hence the molecules are even closer together.
Illinois Physical Science Applications in Agriculture Lesson B3–6 • Page 7
SPECIFIC HEAT
Part One: Matching
Instructions: Match the word with the correct definition.
a. Temperature
b. Gas
c. Solid
d. Latent heat
e. Law of Thermodynamics
f. Convection
g. Kinetic-Molecular Theory
h. Specific heat
_______1. Molecules are held close to each other by their attractions of charge.
_______2. A measure of the average kinetic energy of the molecules of a substance.
_______3. The transfer of heat by movement of the heated part of a gas or liquid.
_______4. Molecules are in a continual straight line motion.
_______5. The amount of heat needed to bring about a change of state.
_______6. Provides an explanation for heat and temperature.
_______7. Heat may not be created or destroyed.
_______8. The heat required to raise one pound of substance one degree Fahrenheit.
Part Two: Fill-in-the-Blank
Instructions: Complete the following statements.
1. The kinetic theory applies to __________, __________, and __________.
2. __________ molecules will flow or glide over one another
3. A ________________ is used to measure the amount of heat lost by an object through transfer
to a liquid.
4. Most metals, such as _____________ and __________, are good heat conductors.
Illinois Physical Science Applications in Agriculture Lesson B3–6 • Page 8
Part Three: Multiple Choice
Instructions: Write the letter of the correct answer.
_______1. The transfer of heat by direct contact.
a. Conduction
b. Convection
c. Radiation
d. Specific heat
_______2. The transfer of heat through space by infrared rays.
a. Conduction
b. Convection
c. Radiation
d. Latent heat
_______3. When two bodies are in contact, heat will flow from a warm body to a cold body until
they are atequal temperatures. This refers to:
a. Calorimetry
b. Kinetic-Molecular Theory
c. Temperature
d. Law of Thermodynamics
_______4. What results from the motion of molecules?
a. Increase in kinetic energy
b. Increase in heat
c. Increase in temperature
d. All of the above
Part Four: Short Answer
Instructions: Answer the following questions.
1. What are the three basic assumptions of the Kinetic-Molecular Theory?
2. What is the difference between specific heat and latent heat?
3. Why are solids generally better conductors than liquids or gases?
Illinois Physical Science Applications in Agriculture Lesson B3–6 • Page 9
Assessment
Technical Supplement
SPECIFIC HEAT
1. What is the Kinetic Molecular Theory?
Kinetic theory is based on the idea that particles of matter are always in motion and
that this motion has consequences. The kinetic theory applies to solids, liquids, and
gases. The kinetic energy of liquid particles is high enough so that they are bound
together just as solid particles are. Particles of liquids can change position with other
liquid particles, although they tend to do so more slowly and less often than do gas
particles.
2. What are the three mechanisms of heat transfer?
Conduction is the transfer of heat by direct contact. This is the simplest method of
heat transfer. A metal poker put directly into a fire is heated by conduction. Convection
is the transfer of heat by movement of the heated part of a gas or liquid. Heat
transfer by convection can take place only in gases or liquids. When a gas such as air
or a liquid such as water is heated unevenly, the heated part rises. This is an example
of convection. Radiation is transfer of heat through space by infrared rays. This heat
transfer does not cause particles of matter to move. The earth receives heat energy
from the sun by radiation. You feel warm while sitting in the sun because you are
receiving heat from the sun by radiation.
3. What are the sources of thermal energy?
Temperature is a description of a condition, a measure of the average kinetic energy
of the particles in a sample matter. Temperature indicates how hot or how cold
something is. The greater the kinetic energy of the particles in a sample of matter,
the higher the temperature of the matter is. Heat is the sum total of the kinetic energies
of the particles in a sample of matter. Heat always flows spontaneously from
Illinois Physical Science Applications in Agriculture Lesson B3–6 • Page 27
matter at a higher temperature to matter at a lower temperature. To illustrate the
difference between temperature and heat, consider a bathtub full of warm water and
a cup of boiling water. The temperature of the water in the tub is lower than that of
the water in the cup. Although the kinetic energy of each particle in the cup is greater
than that of each particle in the tub, the total heat energy in the tub will be much
greater than that in the cup, which has few particles.
4. Why are solids generally better conductors than liquids or gases?
Solids are generally better conductors than liquids or gases because the molecules
are closer together. Most metals, such as aluminum and copper, are good heat conductors.
Other materials, such as wool, straw, paper, cork, and wood are not good
conductors of heat. This is because most metallic elements are denser than cork,
wood, or other non-conductors, hence the molecules are even closer together.
Illinois Physical Science Applications in Agriculture Lesson B3–6 • Page 28