What are the different types of states of matter?

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kevin Mon, Jan 17, 2022 10:47 PM UTC

Matter exists in various physical states, which are determined by the movement of the matter’s particles.

1. 2
States of
Matter exists in various
physical states, which are
determined by the movement
of the matter’s particles.
1 Three States of Matter . . . . . . . 32
2 Behavior of Gases . . . . . . . . . . . 36
3 Changes of State . . . . . . . . . . . . 40
About the
PRE-READING
This beautiful glass creation by artist Dale
Chihuly is entitled “Mille Fiori” (A Thousand
Three-Panel Flip Chart
Flowers). The pieces that form the sculpture Before you read the chapter,
were not always solid and unchanging. Each create the FoldNote entitled
individual piece started as a blob of melted “Three-Panel Flip Chart” described in the
glass on the end of a hollow pipe. The artist Study Skills section of the Appendix.
Label the flaps of the three-panel flip
worked with his assistants to quickly form
chart with “Solid,” “Liquid,” and “Gas.”
each shape before the molten glass cooled As you read the chapter, write informa-
and became a solid again. tion you learn about
each category under
the appropriate flap.
30 Chapter 2

2. Vanishing Act 4. Record your observations.
In this activity, you will use isopropyl alcohol 5. Wash your hands thoroughly.
(rubbing alcohol) to investigate a change of state. Analysis
Procedure 1. Explain what happened to the alcohol after you
1. Pour rubbing alcohol into a small plastic cup rubbed the swab on your hand.
until the alcohol just covers the bottom of 2. Did you feel a sensation of hot or cold? If so,
the cup. how do you explain what you observed?
2. Moisten the tip of a cotton swab by dipping it 3. Record your answers.
into the alcohol in the cup.
3. Rub the cotton swab on the palm of your hand.
Make sure there are no cuts or abrasions on your
hands.
States of Matter 31

3. Three States of Matter
1 You’ve just walked home on one of the coldest days of the
year. A ﬁre is blazing in the ﬁreplace. And there is a pot of
water on the stove to make hot chocolate.
The water begins to bubble. Steam rises from the pot. You
What You Will Learn
make your hot chocolate, but it is too hot to drink. You don’t
Describe the properties shared by want to wait for it to cool down. So, you add an ice cube. You
particles of all matter.
watch the ice melt in the hot liquid until the drink is at just
Describe three states of matter.
the right temperature. Then, you enjoy your hot drink while
Explain the differences between the
warming yourself by the fire.
states of matter.
The scene described above has examples of the three
Vocabulary most familiar states of matter: solid, liquid, and gas. The
states of matter states of matter are the physical forms in which a substance
solid can exist. For example, water commonly exists in three states
liquid of matter: solid (ice), liquid (water), and gas (steam).
surface tension
viscosity Particles of Matter
Matter is made up of tiny particles called atoms and molecules
READING STRATEGY (MAHL i kyoolz). These particles are too small to see without a
very powerful microscope. Atoms and molecules are always in
Paired Summarizing Read this motion and are always bumping into one another. The particles
section silently. In pairs, take turns
summarizing the material. Stop to interact with each other, and the way they interact with each
discuss ideas that seem confusing. other helps determine the state of the matter. Figure 1 describes
three states of matter—solid, liquid, and gas—in terms of the
speed and attraction of the particles.
Figure 1 Models of a Solid, a Liquid, and a Gas
Particles of a solid do not Particles of a liquid move Particles of a gas move fast
move fast enough to over- fast enough to overcome enough to overcome almost
come the strong attraction some of the attraction be- all of the attraction between
between them. So, they are tween them. The particles them. The particles are far
close together and vibrate are close together but can apart and move indepen-
in place. slide past one another. dently of one another.
32 Chapter 2 States of Matter

4. Imagine dropping a marble into a bottle. Would anything states of matter the physical
happen to the shape or size of the marble? Would the shape forms of matter, which include solid,
liquid, and gas
or size of the marble change if you put it in a larger bottle?
solid the state of matter in which
Solids Have Definite Shape and Volume the volume and shape of a substance
are fixed
Even in a bottle, a marble keeps its original shape and
volume. The marble’s shape and volume stay the same no
matter what size bottle you drop it into because the marble is
a solid. A solid is the state of matter that has a definite shape
and volume.
The particles of a substance in a solid state are very close
together. The attraction between them is stronger than the
attraction between the particles of the same substance in the
liquid or gaseous state. The particles in a solid move, but they
do not move fast enough to overcome the attraction between Is Glass a Liquid? At one
them. Each particle vibrates in place. Therefore, each particle time, there was a theory that
is locked in place by the particles around it. glass was a liquid. This theory
came about because of the
There Are Two Kinds of Solids observation that ancient win-
dowpanes were often thicker
There are two kinds of solids—crystalline (KRIS tuhl in) and at the bottom than at the top.
amorphous (uh MAWR fuhs). Crystalline solids have a very People thought that the glass
orderly, three-dimensional arrangement of particles. The par- had flowed to the bottom of
ticles of crystalline solids are in a repeating pattern of rows. the pane, so glass must be a
liquid. Research this theory.
Iron, diamond, and ice are examples of crystalline solids.
Present your research to your
Amorphous solids are made of particles that do not have a class in an oral presentation.
special arrangement. So, each particle is in one place, but the
particles are not arranged in a pattern. Examples of amorphous
solids are glass, rubber, and wax. Figure 2 shows a photo of
quartz (a crystalline solid) and glass (an amorphous solid).
✓ Reading Check How are the particles in a crystalline solid
arranged? (See the Appendix for answers to Reading Checks.)
Figure 2 Crystalline and Amorphous Solids
The particles of crystalline solids,
such as this quartz crystal, have an
orderly three-dimensional pattern.
Glass, an amorphous
solid, is made of particles
that are not arranged in
any particular pattern.
Section 1 Three States of Matter 33

5. Figure 3 Although their shapes
are different, the beaker and the
graduated cylinder each contain
350 mL of juice.
Liquids
liquid the state of matter that has What do you think would change about orange juice if you
a definite volume but not a definite poured the juice from a can into a glass? Would the volume
of juice be different? Would the taste of the juice change?
surface tension the force that
acts on the surface of a liquid and Liquids Change Shape but Not Volume
that tends to minimize the area of
The only thing that would change when the juice is poured
the surface
into the glass is the shape of the juice. The shape changes
viscosity the resistance of a gas or because juice is a liquid. Liquid is the state of matter that has
liquid to flow
a definite volume but takes the shape of its container. The
gas a form of matter that does not particles in liquids move fast enough to overcome some of the
have a definite volume or shape attractions between them. The particles slide past each other
until the liquid takes the shape of its container.
Although liquids change shape, they do not easily change
volume. A can of juice contains a certain volume of liquid.
That volume stays the same if you pour the juice into a large
container or a small one. Figure 3 shows the same volume of
liquid in two different containers.
Liquids Have Unique Characteristics
A special property of liquids is surface tension. Surface tension
is a force that acts on the particles at the surface of a liquid.
Surface tension causes some liquids to form spherical drops,
like the beads of water shown in Figure 4. Different liquids
have different surface tensions. For example, gasoline has a
very low surface tension and forms flat drops.
Another important property of liquids is viscosity. Viscosity is
a liquid’s resistance to flow. Usually, the stronger the attrac-
tions between the molecules of a liquid, the more viscous the
Figure 4 Water forms spherical liquid is. For example, honey flows more slowly than water.
drops as a result of surface tension. So, honey has a higher viscosity than water.
✓Reading Check What is viscosity?
34 Chapter 2 States of Matter

6. Would you believe that one small tank of helium
can fill almost 700 balloons? How is this possible?
After all, the volume of a tank is equal to the
volume of only about five filled balloons. The
answer has to do with helium’s state of matter.
Gases Change in Both Shape and Volume
Helium is a gas. Gas is the state of matter that has
no definite shape or volume. The particles of a gas
move quickly. So, they can break away completely
from one another. There is less attraction between
particles of a gas than between particles of the same
substance in the solid or liquid state.
The amount of empty space between gas par- Figure 5 Many
ticles can change. Look at Figure 5. The particles of balloons can be filled
helium in the balloons are farther apart than the from one tank of
helium because the
particles of helium in the tank. The particles spread particles of helium
out as helium fills the balloon. So, the amount of gas in a balloon are
empty space between the gas particles increases. far apart.
Using Key Terms Interpreting Graphics
Review 1. Use each of the following terms Use the image below to answer the
in a separate sentence: viscosity questions that follow.
and surface tension.
Understanding Key Ideas
Summary 2. One property that all particles of
matter have in common is they
• The three most famil-
iar states of matter are a. never move in solids. 6. Identify the state of matter
solid, liquid, and gas. b. only move in gases. shown in the jar.
• All matter is made of
tiny particles called
c. move constantly.
d. None of the above
7. Discuss how the particles in the
jar are attracted to each other.
atoms and molecules
3. Describe solids, liquids, and gases
that attract each other
in terms of shape and volume.
and move constantly.
• A solid has a definite
shape and volume.
Critical Thinking
Developed and maintained by the
4. Applying Concepts Classify
• A liquid has a definite
volume but not a each substance according to
National Science Teachers Association
For a variety of links related to this
definite shape. its state of matter: apple juice, chapter, go to www.scilinks.org
bread, a textbook, and steam.
• A gas does not have
a definite shape or 5. Identifying Relationships The
Topic: Solids, Liquids, and Gases
SciLinks code: HSM1420
volume. volume of a gas can change, but
the volume of a solid cannot.
Explain why this is true.
35

7. Behavior of Gases
2 Suppose you are watching a parade that you have been
looking forward to for weeks. You may be fascinated by the
giant balloons ﬂoating high overhead.
You may wonder how the balloons were arranged for the parade.
What You Will Learn
How much helium was needed to fill all of the balloons? What
Describe three factors that affect role does the weather play in getting the balloons to float?
how gases behave.
Predict how a change in pressure
or temperature will affect the Describing Gas Behavior
volume of a gas.
Helium is a gas. Gases behave differently from solids or liq-
Vocabulary uids. Unlike the particles that make up solids and liquids, gas
temperature particles have a large amount of empty space between them.
volume The space that gas particles occupy is the gas’s volume, which
pressure can change because of temperature and pressure.
Boyle’s Law
Charles’s Law Temperature
How much helium is needed to fill a parade balloon, like
READING STRATEGY the one in Figure 1? The answer depends on the outdoor
Reading Organizer As you read this temperature. Temperature is a measure of how fast the particles
section, make a table comparing the in an object are moving. The faster the particles are moving,
effects of temperature, volume, and the more energy they have. So, on a hot day, the particles
pressure on gases.
of gas are moving faster and hitting the inside walls of the
balloon harder. Thus, the gas is expanding and pushing on
the walls of the balloon with greater force. If the gas expands
temperature a measure of how too much, the balloon will explode. But, what will happen if
hot (or cold) something is; specifi- the weather is cool on the day of the parade? The particles
cally, a measure of the movement of gas in the balloon will have less energy. And, the particles
of particles.
of gas will not push as hard on the walls of the balloon. So,
more gas must be used to fill the balloons.
Figure 1 To properly inflate
a helium balloon, you must
consider the temperature outside
of the balloon.
36 Chapter 2 States of Matter

8. Volume is the amount of space that an object takes up. But volume a measure of the size
because the particles of a gas spread out, the volume of any of a body or region in three-
dimensional space
gas depends on the container that the gas is in. For exam-
ple, have you seen inflated balloons that were twisted into pressure the amount of force
different shapes? Shaping the balloons was possible because exerted per unit area of a surface
particles of gas can be compressed, or squeezed together, into a
smaller volume. But, if you tried to shape a balloon filled with
water, the balloon would probably explode. It would explode
because particles of liquids can’t be compressed as much as
particles of gases.
The amount of force exerted on a given area of surface is called
pressure. You can think of pressure as the number of times the
particles of a gas hit the inside of their container.
The balls in Figure 2 are the same size, which means they
can hold the same volume of air, which is a gas. Notice,
however, that there are more particles of gas in the basketball For another activity related
than in the beach ball. So, more particles hit the inside surface to this chapter, go to
go.hrw.com and type in
of the basketball than hit the inside surface of the beach ball. the keyword HP5STAW.
When more particles hit the inside surface of the basketball, the
force on the inside surface of the ball increases. This increased
force leads to greater pressure, which makes the basketball feel
harder than the beach ball.
✓Reading Check Why is the pressure greater in a basketball than
in a beach ball? (See the Appendix for answers to Reading Checks.)
Figure 2 Gas and Pressure
High pressure Low pressure
The basketball has a higher pressure because The beach ball has a lower pressure because
there are more particles of gas in it, and they there are fewer particles of gas, and they are
are closer together. The particles collide with farther apart. The particles in the beach ball col-
the inside of the ball at a faster rate. lide with the inside of the ball at a slower rate.
Section 2 Behavior of Gases 37

9. Gas Behavior Laws
Scientists found that the temperature, pressure, and volume of
a gas are linked. Changing one of the factors changes the other
two factors. The relationships between temperature, pressure,
and volume are described by gas laws.
Boyle’s Law
Imagine that a diver 10 m below the surface of a lake blows a
bubble of air. When the bubble reaches the surface, the bubble’s
volume has doubled. The difference in pressure between the
surface and 10 m below the surface caused this change.
The relationship between the volume and pressure of a gas
was first described by Robert Boyle, a 17th-century Irish chem-
Boyle’s law the law that states ist. The relationship is now known as Boyle’s law. Boyle’s law
that the volume of a gas is inversely states that for a fixed amount of gas at a constant temperature,
proportional to the pressure of a gas
the volume of the gas is inversely related to the pressure. So,
when temperature is constant
as the pressure of a gas increases, the volume decreases by the
Charles’s law the law that states same amount, as shown in Figure 3.
that the volume of a gas is directly
proportional to the temperature of a
Charles’s Law
gas when pressure is constant
If you blow air into a balloon and leave it in the hot sun, the
balloon might pop. Charles’s law states that for a fixed amount
of gas at a constant pressure, the volume of the gas changes
in the same way that the temperature of the gas changes. So,
if the temperature increases, the volume of gas also increases
by the same amount. Charles’s law is shown by the model in
Figure 4.
✓Reading Check State Charles’s law in your own words.
Figure 3 Boyle’s Law
Lifting the piston lets the par- Releasing the piston allows the Pushing the piston forces the
ticles of gas spread far apart. The particles of gas to return to their gas particles close together. The
volume of the gas increases as original volume and pressure. volume of the gas decreases as
the pressure decreases. the pressure increases.
38 Chapter 2 States of Matter

10. Figure 4 Charles’s Law
Decreasing the temperature of Increasing the temperature of
the gas causes the particles to the gas causes the particles to
move more slowly. The gas par- move more quickly. The gas parti-
ticles hit the piston less often and cles hit the piston more often and
with less force. So, the volume of with greater force. So, the volume
the gas decreases. of the gas increases.
Using Key Terms Critical Thinking
Review 1. Use each of the following terms 5. Applying Concepts What
in the same sentence: happens to the volume of a
temperature, pressure, volume, balloon that is taken outside
and Charles’s law. on a cold winter day? Explain.
6. Making Inferences When
Summary Understanding Key Ideas scientists record a gas’s volume,
2. Boyle’s law describes the they also record its temperature
• Temperature measures
how fast the particles in
relationship between and pressure. Why?
an object are moving. a. volume and pressure. 7. Analyzing Ideas What happens
to the pressure of a gas if the
• Gas pressure increases
as the number of col-
b. temperature and pressure.
c. temperature and volume. volume of gas is tripled at a
constant temperature?
lisions of gas particles d. All of the above
increases.
3. What are the effects of a warm
• Boyle’s law states that if
the temperature doesn’t
temperature on gas particles?
change, the volume of Math Skills Developed and maintained by the
a gas increases as the National Science Teachers Association
pressure decreases. 4. You have 3 L of gas at a certain For a variety of links related to this
• Charles’s law states that
if the pressure doesn’t
temperature and pressure. What
would the volume of the gas be
chapter, go to www.scilinks.org
if the temperature doubled and Topic: Gas Laws
change, the volume of
a gas increases as the the pressure stayed the same? SciLinks code: HSM0637
temperature increases.
39

11. Changes of State
3 It can be tricky to eat a frozen juice bar outside on a hot day.
In just minutes, the juice bar will start to melt. Soon the solid
juice bar becomes a liquid mess.
As the juice bar melts, it goes through a change of state. In this
What You Will Learn
section, you will learn about the four changes of state shown
Describe how energy is involved in Figure 1 as well as a fifth change of state called sublimation
in changes of state.
(SUHB luh MAY shuhn).
Describe what happens during
melting and freezing.
Compare evaporation and Energy and Changes of State
condensation. A change of state is the change of a substance from one physical
Explain what happens during form to another. All changes of state are physical changes. In a
sublimation. physical change, the identity of a substance does not change.
Identify the two changes that can In Figure 1, the ice, liquid water, and steam are all the same
happen when a substance loses or
gains energy. substance—water.
The particles of a substance move differently depending
Vocabulary on the state of the substance. The particles also have different
change of boiling amounts of energy when the substance is in different states.
state condensation For example, particles in liquid water have more energy than
melting sublimation particles in ice. But particles of steam have more energy than
evaporation particles in liquid water. So, to change a substance from one
state to another, you must add or remove energy.
READING STRATEGY
Mnemonics As you read this
✓Reading Check What is a change of state? (See the Appendix for
answers to Reading Checks.)
section, create a mnemonic device
to help you remember the five
changes of state.
Figure 1 Changes of State
The terms in the arrows are changes of
change of state the change state. Water commonly goes through
of a substance from one physical the changes of state shown here.
state to another
n
Evaporatio
M
on
elt
s a ti
ing
Fr e e
en
nd
zi n
Co
g
40 Chapter 2 States of Matter

12. Melting: Solid to Liquid
One change of state that happens when you add energy
to a substance is melting. Melting is the change of state
from a solid to a liquid. This change of state is what
happens when ice melts. Adding energy to a solid
increases the temperature of the solid. As the temperature
increases, the particles of the solid move faster. When a
certain temperature is reached, the solid will melt. The
temperature at which a substance changes from a solid
to a liquid is the melting point of the substance. Melting
point is a physical property. Different substances have
different melting points. For example, gallium melts at
about 30°C. Because your normal body temperature is
Figure 2 Even though gallium is a
about 37°C, gallium will melt in your hand! This is shown metal, it would not be very useful
in Figure 2. Table salt, however, has a melting point of as jewelry!
801°C, so it will not melt in your hand.
Adding Energy
For a solid to melt, particles must overcome some of their melting the change of state in which a
attractions to each other. When a solid is at its melting solid becomes a liquid by adding energy
point, any energy added to it is used to overcome the
attractions that hold the particles in place. Melting is an
endothermic (EN doh THUHR mik) change because energy
is gained by the substance as it changes state.
Freezing: Liquid to Solid
The change of state from a liquid to a solid is called
freezing. The temperature at which a liquid changes into
a solid is the liquid’s freezing point. Freezing is the reverse
process of melting. Thus, freezing and melting occur at
the same temperature, as shown in Figure 3.
Removing Energy
Figure 3 Liquid water freezes
For a liquid to freeze, the attrac- at the same temperature at
tions between the particles must which ice melts—0°C.
overcome the motion of the
particles. Imagine that a liquid is
at its freezing point. Removing If energy is added at
energy will cause the particles 0°C, the ice will melt.
to begin locking into place.
Freezing is an exothermic (EK so
If energy is removed
THUHR mik) change because
at 0°C, the liquid
energy is removed from the water will freeze.
substance as it changes state.
Section 3 Changes of State 41

13. Evaporation: Liquid to Gas
One way to experience evaporation is to iron a shirt using a
steam iron. You will notice steam coming up from the iron
as the wrinkles disappear. This steam forms when the liquid
water in the iron becomes hot and changes to gas.
Boiling and Evaporation
evaporation the change of a Evaporation (ee VAP uh RAY shuhn) is the change of a substance
substance from a liquid to a gas from a liquid to a gas. Evaporation can occur at the surface of
boiling the conversion of a a liquid that is below its boiling point. For example, when you
liquid to a vapor when the vapor sweat, your body is cooled through evaporation. Your sweat
pressure of the liquid equals the is mostly water. Water absorbs energy from your skin as the
atmospheric pressure
water evaporates. You feel cooler because your body transfers
energy to the water. Evaporation also explains why water in
a glass on a table disappears after several days.
Figure 4 explains the difference between boiling and
evaporation. Boiling is the change of a liquid to a vapor, or
gas, throughout the liquid. Boiling occurs when the pressure
inside the bubbles, which is called vapor pressure, equals the
outside pressure on the bubbles, or atmospheric pressure. The
temperature at which a liquid boils is called its boiling point.
No matter how much of a substance is present, neither the
boiling point nor the melting point of a substance change. For
example, 5 mL and 5 L of water both boil at 100°C.
✓Reading Check What is evaporation?
Figure 4 Boiling and Evaporation
Boiling Boiling
point point
Boiling occurs in a liquid at its boiling point. Evaporation can also occur in a liquid below
As energy is added to the liquid, particles its boiling point. Some particles at the surface
throughout the liquid move faster. When they of the liquid move fast enough to break away
move fast enough to break away from other from the particles around them and become
particles, they evaporate and become a gas. a gas.
42 Chapter 2 States of Matter

14. Effects of Pressure on Boiling Point
Earlier, you learned that water boils at 100°C. In fact, water
boils at 100°C only at sea level, because of atmospheric
pressure. Atmospheric pressure is caused by the weight of the
WRITING Cooking at High
gases that make up the atmosphere. SKILL Altitudes Many
Atmospheric pressure varies depending on where you are in times, cake mixes and other
relation to sea level. Atmospheric pressure is lower at higher prepared foods will have
elevations. The higher you go above sea level, the fewer air special instructions for baking
particles there are above you. So, the atmospheric pressure is and cooking at high altitudes.
Even poaching an egg at a high
lower. Imagine boiling water at the top of a mountain. The
altitude requires a different
boiling point would be lower than 100°C. For example, Denver, amount of cooking time. Imag-
Colorado, is 1.6 km above sea level. In Denver, water boils at ine that you got a letter from a
about 95°C. cousin in Denver. He is upset
that a cake he made turned out
poorly, even though he fol-
Condensation: Gas to Liquid lowed the recipe. Do research
Look at the dragonfly in Figure 5. Notice the beads of water on cooking at high altitudes.
that have formed on the wings. They form because of Write a letter to your cousin
explaining why he may have
condensation of gaseous water in the air. Condensation is the
had problems baking the cake.
change of state from a gas to a liquid. Condensation and evapo-
ration are the reverse of each other. The condensation point of
a substance is the temperature at which the gas becomes a
liquid. And the condensation point is the same temperature
as the boiling point at a given pressure.
For a gas to become a liquid, large numbers of particles must
clump together. Particles clump together when the attraction condensation the change of
between them overcomes their motion. For this to happen, state from a gas to a liquid
energy must be removed from the gas to slow the movement
of the particles. Because energy is removed, condensation is
an exothermic change.
Figure 5 Beads of water
form when water vapor
in the air contacts a cool
surface, such as the wings
of this dragonfly.
Section 3 Changes of State 43

15. Sublimation: Solid to Gas
The solid in Figure 6 is dry ice. Dry ice is carbon
dioxide in a solid state. It is called dry ice because
instead of melting into a liquid, it goes through
sublimation. Sublimation is the change of state in
which a solid changes directly into a gas. Dry ice
is much colder than ice made from water.
For a solid to change directly into a gas, the
particles of the substance must move from being
very tightly packed to being spread far apart.
So, the attractions between the particles must
be completely overcome. The substance must
gain energy for the particles to overcome their
attractions. Thus, sublimation is an endothermic
change because energy is gained by the substance
as it changes state.
Figure 6 Dry ice changes directly
from a solid to a gas. This change
Change of Temperature Vs. Change of State
of state is called sublimation. When most substances lose or gain energy, one of two
things happens to the substance: its temperature changes
or its state changes. The temperature of a substance is
related to the speed of the substance’s particles. So, when
the temperature of a substance changes, the speed of the
particles also changes. But the temperature of a substance
sublimation the process in which
a solid changes directly into a gas does not change until the change of state is complete.
For example, the temperature of boiling water stays at
100°C until it has all evaporated. In Figure 7, you can see
what happens to ice as energy is added to the ice.
✓ Reading Check What happens to the temperature of a
substance as it changes state?
Boiling Water Is Cool
1. Remove the cap from a syringe.
2. Place the tip of the syringe in the warm water that is
provided by your teacher. Pull the plunger out until you
have 10 mL of water in the syringe.
3. Tighten the cap on the syringe.
4. Hold the syringe, and slowly pull the plunger out.
5. Observe any changes you see in the water. Record your
observations.
6. Why are you not burned by the water in the syringe?
44 Chapter 2 States of Matter

16. Figure 7 Changing the State of Water
D
Boiling point
DE
100
AD
Temperature (°C)
ADDED ENERGY
GY
ER
EN
Melting point D
The energy that is added during a change of
0 E
DD state is used to break the attractions between
ENERGY A
particles. So, the temperature does not change
until the change of state is complete.
Time
Using Key Terms Critical Thinking
Review For each pair of terms, explain how 8. Evaluating Data The tempera-
the meanings of the terms differ. ture of water in a beaker is 25°C.
After adding a piece of magne-
1. melting and freezing
sium to the water, the tempera-
2. condensation and evaporation ture increases to 28°C. Is this an
Summary exothermic or endothermic
Understanding Key Ideas reaction? Explain your answer.
• Aconversion
change of state is the
of a sub-
3. The change from a solid directly 9. Applying Concepts Solid
to a gas is called crystals of iodine were placed in
stance from one physical a flask. The top of the flask was
form to another. a. evaporation.
covered with aluminum foil. The
• Energy is added during
endothermic changes.
b. boiling.
c. melting.
flask was gently heated. Soon,
the flask was filled with a red-
Energy is removed dur- d. sublimation. dish gas. What change of state
ing exothermic changes. took place? Explain your answer.
4. Describe how the motion and
• The freezing point and
the melting point of a
arrangement of particles in a 10. Predicting Consequences
substance change as the Would using dry ice in your
substance are the same substance freezes. holiday punch cause it to
temperature. become watery after several
5. Explain what happens to the
• Both boiling and evapo-
ration result in a liquid
temperature of an ice cube as it hours? Why or why not?
melts.
changing to a gas.
• Condensation is the
change of a gas to a
6. How are evaporation and boiling
different? How are they similar?
liquid. It is the reverse
of evaporation. Math Skills
• Sublimation changes a
solid directly to a gas.
7. The volume of a substance in
For a variety of links related to this
chapter, go to www.scilinks.org
the gaseous state is about 1,000
• The temperature of a
substance does not
times the volume of the same
substance in the liquid state.
Topic: Changes of State
SciLinks code: HSM0254
change during a change How much space would 18 mL
of state. of water take up if it evaporated?
45

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