Study Guide — Unit 3 Chapter 6
DRAFT
Unit 3
Energy and Society
Chapter 5 Work, Energy, Power and Society
BIG IDEAS
• Energy can be transformed from one type
into another.
• Energy transformation systems often
involve thermal energy losses and are never
100 % efficient.
• Although technological applications that
involve energy transformations can affect
society and the environment in positive ways,
they can also have negative effects, and
therefore must be used responsibly.
Work, energy, and power are related concepts that affect everyday life, society, and the
environment. In science, energy is defined as the capacity to do work. There are many
types of energy and they can all be categorized as potential energy, kinetic energy, or a
combination of both.
The law of conservation of energy states that the total amount of energy in the
universe does not change. Energy cannot be created nor destroyed, but it can be
transformed.
Power is the rate at which energy is transformed; efficiency quantifies the
amount of useful energy produced when energy is transformed. The selection and use
of renewable or nonrenewable energy resources have an impact on society and the
environment.
Chapter 6 Thermal Energy and Society
Thermal energy, temperature, and heat are similar concepts, but these terms are not
interchangeable. Thermal energy is the total amount of potential and kinetic energy
possessed by the particles of a substance. Temperature is the average kinetic energy of
the particles. Heat is the term used to describe the transfer of thermal energy. Change in
the thermal energy of a substance can cause changes of state, such as melting or
freezing.
Heating and cooling systems, which keep homes, schools, and businesses
comfortable, are familiar applications of thermal energy, temperature, and heat. These
systems can have both positive and negative impacts on the environment.
Chapter 7 Nuclear Energy and Society
Nuclear energy is released during changes in the structure of atomic nuclei. Some forms
of atoms, called isotopes, change spontaneously, releasing energy called radiation. This
process has practical applications, such as carbon-14 dating and medical diagnosis.
There are several different types of radioactive decay reactions
Very large amounts of energy are released in fission reactions, making nuclear
fission a useful energy source. However, there are safety and waste disposal issues
related to the use of nuclear fission as a power source.
Nuclear fusion, which is the source of energy for the Sun and other stars, is a
reaction in which the nuclei of two atoms fuse and a great amount of energy is released.
Nuclear fusion is better than nuclear fission from an environmental standpoint, but it is
very difficult to achieve. At present it is not a practical source of energy.
Copyright 2011 by Nelson Education Ltd.
DRAFT
Unit 3 Overview
6.1
Warmth and Coldness
Vocabulary
kinetic molecular theory
thermal energy
temperature
Celsius scale
Textbook pp. 270–274
Fahrenheit scale
Kelvin scale
melting point
freezing point
boiling point
condensation point
Main idea: Thermal energy is the total potential energy and the total kinetic energy
possessed by the particles of a substance.
1.
The SI unit used to measure thermal energy is the ____________. [K/U]
2.
The thermal energy of a substance includes both the ___________________ and
the _______________ of the particles of the substance. [K/U]
3.
The ______________ of the particles of a substance is associated with the motion
of the particles. [K/U]
4.
The ______________ of the particles of a substance is associated with the force of
attraction between the particles. [K/U]
Main idea: Temperature is a measure of the average kinetic energy of the particles in a
substance.
5.
Compare and contrast the thermal energy of a substance and the temperature of
the substance. [T/I] [C]
Main idea: The kinetic molecular theory states that as particles of matter gain kinetic
energy, they move faster and the temperature of the substance increases. Similarly, as
particles of matter lose kinetic energy, they move more slowly and the temperature of the
substance decreases.
6.
Fill in the flow chart below using the words increases and decreases to describe the
relationship between temperature of a substance and the kinetic energy of the
particles of the substance. [K/U] [C]
STUDY TIP
Flow Charts
gain kinetic
energy
You can use flow charts to summarize and
order the steps in a process.
particles of
matter
lose kinetic
energy
Copyright 2011 by Nelson Education Ltd.
DRAFT
speed of
their motion
_______
speed of
their motion
_______
temperature
of the matter
_________
_
temperature
of the matter
_________
_
Unit 3 Chapter 6 1
Main idea: Temperature can be measured using the Celsius scale, Fahrenheit scale, or
Kelvin scale. Scientists typically use the Kelvin scale because kelvins are SI units.
7.
Fill in the blanks below to describe the Fahrenheit and Celsius scales. [K/U]
Celsius scale
Created by: ________________________
Boiling point of pure water: ___________
Freezing point of pure water: __________
Fahrenheit scale
Created by: _________________________
Boiling point of pure water: ____________
Freezing point of pure water: ___________
8.
Describe the motion of particles in a substance at absolute 0, or 0 K. [K/U]
Main idea: The equations TC = TK – 273 and TK = TC + 273 can be used to convert
temperatures from one scale to the other.
9.
Fill in Table 1 below to practise converting temperatures from one scale to
another. [T/I]
Table 1 Temperature Conversions
Celsius
(a)
45 °C
(b)
(c)
Copyright 2011 by Nelson Education Ltd.
Kelvin
120 K
–12 °C
DRAFT
Unit 3 Chapter 6 2
6.2
Heat
Vocabulary
Textbook pp. 275–280
heat
thermal conduction
convection
convection current
radiation
thermal conductor
thermal insulator
Main idea: Thermal energy is the total amount of kinetic energy and potential energy of
the particles in a substance.
1.
What two types of energy make up the thermal energy of a substance? [K/U]
2.
The thermal energy in the particles of a substance determines the _____________
of the substance. [K/U]
3.
Two objects of the same mass and the same material that have the same thermal
energy will have the same ___________. [K/U]
13. Fill in the missing terms in the concept map below to describe the relationship
between changes in thermal energy and changes in temperature. [T/I]
STUDY TIP
Concept Maps
When a substance absorbs energy, some of the energy
You use a concept map to the describe
relationships between processes.
increases the____________ energy
of the particles
which
increases the temperature
of the object
increases the ___________ energy
of the particles
which
does not increase the temperature
of the object
14. As described in the flow chart above, the energy that a substance absorbs changes
both the potential energy and the kinetic energy of the particles of the substance. Is
the percentage of the added energy that changes kinetic energy and the percentage
of the added energy that changes potential energy the same for all substances, or
does it vary between substances? [K/U]
Main idea: Heat is the transfer of thermal energy from a warmer object to a cooler one.
15. Contrast the meaning of the terms heat and thermal energy. [K/U] [C]
Copyright 2011 by Nelson Education Ltd.
DRAFT
Unit 3 Chapter 6 3
Main idea: Thermal energy can be transferred in three different ways: by thermal
conduction, by convection, or by radiation.
16. Fill in Table 1 below to describe conduction, convection, and radiation. [K/U]
Table 1 Thermal Energy Transfer
Type of thermal energy
Definition
transfer
Everyday example
conduction
convection
radiation
17. Define each of the following terms in your own words and provide one example of
each. [K/U]
(a) A thermal conductor is
One example of a good thermal conductor is ________________.
(b) A thermal insulator is
One example of good thermal insulator is __________________.
Copyright 2011 by Nelson Education Ltd.
DRAFT
Unit 3 Chapter 6 4
6.3
Heat Capacity
Vocabulary
specific heat capacity (c)
quantity of heat (Q)
Textbook pp. 281–287
principle of thermal energy exchange
thermal expansion
thermal contraction
Main idea: Specific heat capacity is the amount of heat needed to raise the
temperature of a 1 kg sample of a substance by 1 °C.
Table 1 Specific Heat Capacities of Common Substances
Substance
Specific heat capacity (J/(kg•°C))
water
4.18 × 103
ethyl alcohol
2.46 × 103
ice
2.1 × 103
aluminum
9.2 × 102
glass
8.4 × 102
iron
4.5 × 102
copper
3.8 × 102
silver
2.4 × 102
lead
1.3 × 102
1.
Suppose 10 J of energy is added to 0.1 kg of each substance shown in Table 1
above. [T/I]
(a) Which substance will experience the greatest change in temperature?
(b) Which substance will experience the least change in temperature?
(c) Explain the reasoning you used to arrive at your answers for parts (a) and (b).
Copyright 2011 by Nelson Education Ltd.
DRAFT
Unit 3 Chapter 6 5
LEARNING TIP
Units of Mass in the Heat Equation
Since the units for specific heat capacity are
joules per kilogram per degree Celsius, mass
must be expressed in kilograms when using the
quantity of heat equation.
Main idea: The quantity of heat, or amount of thermal energy absorbed or released by
an object, can be calculated using the equation Q = mc∆T .
2.
For each variable in the equation Q = mc∆T , identify the meaning of the
variable and the units used. [K/U]
(a) Q stands for ____________________; measured in units of ___________.
(b) m stands for ____________________; measured in units of ___________.
(c) c stands for ____________________; measured in units of ___________.
(d) ΔT stands for ____________________; measured in units of ___________.
3.
A block of iron with a mass of 23 kg is heated from 25 °C to 65 °C. How much
thermal energy is absorbed by the iron? Use the space below for your
calculations. [T/I]
4.
A sample of water is cooled from 82 °C to 75 °C, releasing 1567.5 J of energy into
the air around it. Determine the mass of the sample of water. Use the space
below for your calculations. [T/I]
STUDY TIP
Showing your work
Showing each step in a calculation can help you
eliminate errors in your work.
Copyright 2011 by Nelson Education Ltd.
DRAFT
Unit 3 Chapter 6 6
Main idea: The principle of heat exchange states that thermal energy moves from a
warm object to a cooler one until both objects reach a new constant temperature. This
principle can be represented by the equation Qreleased + Qabsorbed = 0.
5.
Does the equation Qreleased + Qabsorbed = 0 reflect the law of conservation of energy?
Explain why or why not. [T/I] [C]
6.
What assumption is made when using the equation Qreleased + Qabsorbed = 0 to
describe thermal energy exchange? Is this assumption realistic in everyday
settings? [T/I] [C]
Main idea: The absorption or release of thermal energy results in thermal expansion or
contraction.
7.
An increase in the thermal energy of a substance causes the particles to spread
out, resulting in ________________. [K/U]
8.
A decrease in the thermal energy of a substance causes the particles to move
closer together, resulting in ________________. [K/U]
9.
Identify an everyday object that has been designed to accommodate thermal
expansion and contraction, and describe specifically how the object’s design
allows for thermal expansion and contraction. [T/I]
Copyright 2011 by Nelson Education Ltd.
DRAFT
Unit 3 Chapter 6 7
6.4
States of Matter and Changes of State
Vocabulary
fusion
heating graph
cooling graph
Textbook pp. 288–295
latent heat (Q)
latent heat of fusion
latent heat of vaporization
specific latent heat (L)
specific latent heat of fusion (Lf)
specific latent heat of vaporization (Lv)
Main idea: The three states of matter are solid, liquid, and gas. When thermal energy is
released or absorbed a change in state may happen.
1. Label the states of matter in Figure 1 below. [K/U]
Figure 1
2.
Complete the statements to describe what happens in the Figure 2 below. Use the
terms increases, decreases, or remains unchanged to fill in the blanks. [T/I]
Figure 2
Between (a) and (b), thermal energy _____________ and temperature
________________.
Between (b) and (c), thermal energy _____________ and temperature
________________. >
Between (c) and (d), thermal energy _____________ and temperature
________________.
Between (d) and (e), thermal energy _____________ and temperature
________________.
3.
In some of the descriptions above, thermal energy increased, yet temperature
Copyright 2011 by Nelson Education Ltd.
DRAFT
Unit 3 Chapter 6 8
remained unchanged. How can this occur if energy is conserved? [T/I]
Main idea: The change in temperature that occurs as a substance releases or absorbs
thermal energy can be shown in a cooling graph or a heating graph.
Use Figure 3 to complete questions 4 and 5.
STUDY TIP
Line Graphs
Line graphs can be used to show how a
change in one variable is associated with a
change in another variable.
Figure 3
4.
The vertical dotted lines in Figure 3, divide the graph into five sections, from left
to right. Mark an X on any section that represents a change of state. [T/I]
5.
If the y-axis of the graph above was labelled “Thermal Energy” rather than
“Temperature,” would the line have the same shape? Explain. [T/I]
Main idea: The thermal energy that is absorbed or released during a change of state is
called the latent heat of the substance. If the substance is melting or freezing it is called
latent heat of fusion. If the substance is evaporating or condensing, it is called the latent
heat of vaporization.
6.
What is the SI unit for latent heat? [K/U] _____________
7.
Latent heat of fusion is the amount of energy absorbed when a substance
___________ or released when a substance__________. [K/U]
8.
Latent heat of vaporization is the amount of energy absorbed when a substance
___________ or released when the substance__________. [K/U]
Copyright 2011 by Nelson Education Ltd.
DRAFT
Unit 3 Chapter 6 9
LEARNING TIP
Remember Units
As with all questions in physics, make sure
the units in your calculations of latent heat
match. Mass must by expressed in
kilograms, and latent heat is expressed in
joules since the units for specific latent heat
are joules per kilogram.
Main idea: The specific latent heat of fusion (Lf), is the amount of thermal energy per
kilogram needed to melt or freeze a substance. The specific latent heat of vaporization
(Lv), is the amount of thermal energy needed per kilogram to evaporate or condense a
substance.
9.
For any specific substance, explain why a single value can be used for both the
latent heat associated with melting and the latent heat associated with freezing.
[K/U]
Main idea: The equation Q = mLf is used to calculate the latent heat of fusion, and
Q = mLv is used to calculate the latent heat of vaporization.
10. How much thermal energy is released by a 24 g ice cube as it melts? The specific
latent heat of fusion of water of water is 3.4 × 105 J/kg. Use the space below for
your calculations. [T/I]
Main idea: Ice is one of the few solids that floats in its liquid; this is due to the shape of
its molecules and the forces of attraction between its molecules.
11. Temperature of a sample of water changes from 20 °C to 0 °C. What happens to its
volume? [K/U]
12. Describe one practical consideration that must be considered related to your
answer to question 11. [T/I]
Copyright 2011 by Nelson Education Ltd.
DRAFT
Unit 3 Chapter 6 10
6.5
Heating and Cooling Systems
Vocabulary
electrical heating system
forced-air heating system
Textbook pp. 296–299
hot water heating system
geothermal system
Main idea: All heating systems have a source of thermal energy, a means of transferring
the energy, and a thermostat to control the production and distribution of energy.
Conventional heating systems use either electricity or fossil fuels as a source of thermal
energy.
1.
Compare and contrast forced-air heating systems and hot water heating systems.
Identify one way they are similar and one way that they are different. [K/U]
Main idea: Conventional cooling systems use the evaporation of pressurized refrigerants
to absorb thermal energy from the air, resulting in cool air that can then be blown through
a duct system.
2.
Fill in the cycle diagram below to describe how cooling systems work. Use the
following sentences to fill in the cycle diagram. [K/U]
• Warm refrigerant gas releases thermal energy and changes to a liquid.
• Liquid refrigerant evaporates into a gas.
• Liquid refrigerant absorbs thermal energy from surroundings.
• Temperature of refrigerant gas increases.
STUDY TIP
Cycle Diagrams
Refrigerant gas is
compressed.
You can use a cycle diagram to learn about
a process that occurs in a series of
repeating steps.
Liquid refrigerant
passes through an
expansion valve.
Copyright 2011 by Nelson Education Ltd.
DRAFT
Unit 3 Chapter 6 11
Main idea: A typical thermostat uses a bimetallic strip and a mercury switch to turn a
heating or cooling system on or off as temperatures change.
3.
Use the concepts of thermal expansion and contraction to explain why a bimetallic
strip, rather than a strip made of a single type of metal, is used in many
thermostats. [T/I] [A]
Main idea: Conventional heating and cooling systems produce greenhouse gases such as
carbon dioxide, so they are not considered environmentally friendly.
4.
Identify one specific way in which conventional heating systems can damage the
environment, and one specific way in which conventional cooling systems can
damage the environment. [K/U] [C]
Main idea: Geothermal systems use Earth’s natural thermal energy for heating and
cooling purposes. In the winter thermal energy is transferred from below Earth’s surface
into a building to heat it. In the summer, thermal energy is transferred from a building into
Earth’s surface to cool it.
5.
Is the following statement true or false? If you think the statement is false, rewrite it
to make it true: In a geothermal system, thermal energy in Earth’s crust is used to
heat and cool homes. [K/U]
6.
During the winter, temperatures underground are ___________ than those above
ground. In the summer, the temperatures underground are _________ than those
above ground. [K/U]
Copyright 2011 by Nelson Education Ltd.
DRAFT
Unit 3 Chapter 6 12
6.6
Textbook pp.300–301
Explore an Issue in Thermal Energy
Geothermal Systems: Friend or Foe?
Main idea: Geothermal heating and cooling systems are promoted as an environmentally
safe alternative to using fossil fuels, but geothermal systems have risks of their own.
1.
Through your research, what did you find to be the benefits, and risks and costs of
geothermal systems? Record your findings in Table 1. [T/I][C]
Table 1 Geothermal Systems
Benefits
Risks and Costs
STUDY TIP
T-Charts
You can use a T-chart to organize and
compare information you find during
research.
2.
Based on what you have learned in your research, do you think the benefits of
geothermal systems outweigh the risks and costs? Explain. [T/I]
Copyright 2011 by Nelson Education Ltd.
DRAFT
Unit 3 Chapter 6 13
6.7
Textbook pp.302–203
Physics Journal
When a Brewer Becomes a Scientist
Main idea: Often, scientific breakthroughs and understanding are the result of
practical interest.
STUDY TIP
Questioning
Questions about a reading passage can be
used to help you understand the main ideas .
1.
How Did Joule’s love of science first develop? [K/U]
2.
Were Joule’s early results well received by the scientific community? Why or
why not? [K/U]
3.
Describe the understanding of thermal energy that most scientists of Joule’s
time shared. [K/U]
4.
How did Joule’s understanding of thermal energy differ from the prevailing
scientific idea of his time? [K/U]
5.
How did Joule demonstrate that mechanical energy could be transformed into
thermal energy? [K/U]
6.
Was Joule’s work eventually accepted? Explain. [K/U]
Copyright 2011 by Nelson Education Ltd.
DRAFT
Unit 3 Chapter 6 14
Chapter 6 Summary
Thermal Energy and Society
Matter
can change states when
thermal energy is
made up of
particles
which have
absorbed
or
released
kinetic energy
average
kinetic energy
thermal energy
(total kinetic +
potential energy)
the transfer of which is
called heat
expressed as a
temperature
on the
Celsius
scale
Fahrenheit
scale
Copyright 2011 by Nelson Education Ltd.
Kelvin
scale
DRAFT
Unit 3 Chapter 6 15
Chapter 6 Questions
K/U
C
T/I
A
Knowledge/Understanding
Communication
Thinking/Investigation
Application
For each question, select the best answer from the four alternatives.
1. At which temperature do the particles of a substance have the least kinetic energy? (6.1) [K/U] K/U
(a) 212 °F
(b) 100 °C
(c) 100 K
(d) –273 °C
2. Which of the following is classified as a thermal conductor? (6.2) [K/U]
(a) wool
(b) copper
(c) air
(d) plastic
Indicate whether each statement is true or false. If you think the statement is false, rewrite it to make it true.
3. The specific heat capacity of water is high in comparison to most common liquids. (6.3) [K/U]
4. The particles of an ice cube have greater kinetic energy than the particles in a cup of liquid water. (6.4) [K/U]
Respond to each statement or answer each question below.
5. You taste a bit of soup, and it burns your tongue. You set the soup aside for several minutes, and then taste the
soup again. Now it can be eaten. Explain what has occurred in terms of the kinetic energy of the particles of the
soup. (6.1) [T/I] [A]
6. Compare the thermal energy and temperatures of the following two samples of water: Sample A is 0.5 mL, and
Sample B is 100 mL. The particles in each sample have the same kinetic energy. (6.2) [T/I] [A]
7. Identify one benefit of geothermal systems and one risk or cost of geothermal systems. (6.6) [T/I]
8. Three qualities that many scientists possess are curiosity, perseverance, and independent thinking. Choose one
of these qualities, and describe how that quality was displayed by James Prescott Joule. (6.7) [T/I]
Copyright 2011 by Nelson Education Ltd.
DRAFT
Unit 3 Chapter 6 16
9. Fill in the blanks with the term that best represents following temperatures. (6.1) [K/U]
(a) temperature at which liquid change to gas: _____________________________
(b) temperature at which solid changes to liquid: _____________________________
(c) temperature at which gas changes to liquid: _____________________________
(d) temperature at which liquid changes to solid: _____________________________
10. Complete the concept map below with the terms convection, radiation, and conduction. (6.2) [K/U] [C]
which
is
Thermal energy
can be
transferred by
which
is
which
is
the transfer of thermal energy
through a fluid when colder,
denser fluid falls and pushes up
warmer, less dense fluid
the transfer of thermal energy
that occurs when objects are in
physical contact
the movement of thermal energy
as electromagnetic waves
11. Fill in the flow chart below, describing what happens as the temperature of a sample of water is cooled from
110 °C to -10 °C. Use the following phrases to complete the flow chart: (6.4) [T/I] [C]
• water vapour condenses into liquid water
• liquid water cools down
• liquid water freezes into ice
• ice cools down
• water vapour cools down
110 °C
(a)
–10 °C
(b)
Copyright 2011 by Nelson Education Ltd.
(c)
DRAFT
(d)
(e)
Unit 3 Chapter 6 17