CHAPTER 10
LESSON 1
Mixtures, Solubility, and
Acid/Base Solutions
Substances and Mixtures
Key Concepts
What do you think? Read the two statements below and decide
whether you agree or disagree with them. Place an A in the Before column
if you agree with the statement or a D if you disagree. After you’ve read
this lesson, reread the statements to see if you have changed your mind.
Before
Statement
After
1. You can identify a mixture by looking at it
without magnification.
• How do substances and
mixtures differ?
• How do solutions compare
and contrast with
heterogeneous mixtures?
• In what three ways do
compounds differ from
mixtures?
2. A solution is another name for a homogeneous
mixture.
3TUDY #OACH
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Matter: Substances and Mixtures
Many different types of matter exist around you. On your
way to school, you might see metal, plastic, rocks, concrete,
plants, fabric, water, and skin. You might notice that you
can group some types of matter together into one category.
For example, keys, coins, and paper clips are made of metal.
Grouping matter into categories helps you understand how
some things are similar to each other, but different from
other things. Nearly all types of matter can be sorted into just
two major categories—substances and mixtures.
Make a Table with two
columns to contrast
substances and mixtures.
Label one column Substances
and the other column
Mixtures. Complete the table
as you read this lesson.
What is a substance?
A substance is matter that is always made up of the same
combination of atoms. There are two types of substances—
elements and compounds. Recall that an element is matter
made of only one type of atom, such as carbon (C), oxygen
(O2), and chlorine (Cl2). A compound is matter made of
atoms of two or more elements that are chemically bonded
together. For example, water (H2O) always contains two
atoms of hydrogen bonded to one atom of oxygen. Table salt
(NaCl) always contains one atom of sodium bonded to one
atom of chlorine. The composition of elements and
compounds doesn’t change. Therefore, all elements and
compounds are substances.
Reading Essentials
Reading Check
1. Analyze Is table salt an
element or a compound?
Explain.
Mixtures, Solubility, and Acid/Base Solutions
171
What is a mixture?
Combine a two-tab and a
four-tab book to organize
your notes on matter.
Two Types of Matter
Substances
Mixtures
us
us
Elements Compounds Heterogeneo Homogeneo
Key Concept Check
2. Contrast How do
substances and mixtures
differ?
A mixture is two or more substances that are physically blended
but are not chemically bonded together. Therefore, the relative
amounts of each substance in a mixture can vary. Granite, a
type of rock, is a mixture. Granite contains bits that are
white, black, and other colors. Two pieces of granite will
have different amounts of each color bit. The composition
of rocks varies. Air is also a mixture. Air contains about
78 percent nitrogen, 21 percent oxygen, and 1 percent other
substances. But this composition varies. Air in a scuba tank
can have more than 21 percent oxygen and less of the other
substances.
Rocks and air are examples of the two different types of
mixtures—heterogeneous (he tuh roh JEE nee us) and
homogeneous (hoh muh JEE nee us). It’s not always easy to
identify a mixture. A rock looks like a mixture, but air does
not.
Heterogeneous Mixtures A heterogeneous mixture is a mixture
in which substances are not evenly mixed. For example, granite is a
heterogeneous mixture. The substances that make up granite
are unevenly mixed. When you look at a piece of granite,
you can easily see the different parts.
Key Concept Check
Solutions—Homogeneous Mixtures Many mixtures look
Visual Check
4. Interpret Can a
mixture be made only of
elements? Explain.
evenly mixed, even when you view them with a powerful
microscope. These mixtures are homogeneous. A homogeneous
mixture is a mixture in which two or more substances are evenly mixed
on the atomic level but not bonded together. The individual atoms
or compounds of each substance are mixed. The mixture
looks the same throughout under a microscope because
individual atoms and compounds are too small to see. Air is
a homogeneous mixture. If you view air under a microscope,
you can’t see the individual substances that make it up.
Another name for a homogeneous mixture is solution. As you
read, remember that the terms homogeneous mixture and
solution mean the same thing. Review the figure on the next
page. It summarizes the characteristics of substances and
mixtures.
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Mixtures, Solubility, and Acid/Base Solutions
Reading Essentials
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
3. Distinguish How can
you determine whether a
mixture is homogeneous or
heterogeneous?
Often, you can see the different substances and parts of a
heterogeneous mixture with unaided eyes. Sometimes you
can see them only with a microscope. For example, blood
looks evenly mixed—its color and texture are the same
throughout. But suppose you compare two samples of blood
under a microscope. They will look different. The samples
will contain different amounts of the components.
Characteristics of Substances and Mixtures
Matter
• anything that has mass and takes up space
• Most matter on Earth is made up of atoms.
Substances
• matter with a composition that
is always the same
• two types of substances:
elements and compounds
Elements
• consists of just one type of atom
• organized on the periodic table
• Elements can exist as single atoms
or as a diatomic molecule–two
atoms bonded together.
Compounds
• made of two or more types of atoms
bonded together
• can’t be separated by physical methods
• properties are different from the
properties of the elements that make
them up
• two types: ionic and covalent
Chemical
changes
Separating mixtures
• filtering
• boiling
• using a magnet
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Physical
changes
Combining substances
• mixing
• dissolving
Mixtures
•
•
•
•
matter that can vary in composition
made of two or more substances mixed but not bonded together
can be separated into substances by physical methods
Two types of mixtures: heterogeneous and homogeneous
Heterogeneous mixtures
• two or more substances unevenly
mixed
• uneven mixing is visible with unaided
eyes or a microscope
Reading Essentials
Homogeneous mixtures (solutions)
• two or more substances evenly mixed
• Homogeneous mixtures appear
uniform under a microscope.
Mixtures, Solubility, and Acid/Base Solutions
173
How do compounds and
mixtures differ?
You have read that a compound contains two or more
elements that are chemically bonded together. In contrast,
the substances that make up a mixture are not chemically
bonded. Therefore, mixing is a physical change. The
substances that exist before mixing still exist in the mixture.
This leads to two important differences between compounds
and mixtures.
Substances keep their properties.
Substances that make up a mixture are not changed
chemically. Therefore, you can observe some of their
properties in the mixture. Sugar water is a mixture of two
compounds—sugar and water. After the sugar is mixed in,
you can’t see the sugar in the water, but you can still taste its
property of sweetness. You can also observe some properties
of the water, such as its liquid state.
5. Apply Seawater is a
mixture of mainly salts and
water. What properties of
these substances can you
observe in seawater?
In contrast, the properties of a compound can be
different from the properties of the elements that make it
up. Sodium and chlorine bond and form table salt. Sodium
is a soft, opaque, silvery metal. Chlorine is a greenish,
poisonous gas. You cannot observe any of these properties
in table salt.
Key Concept Check
The substances that make up a mixture are not bonded
together. As a result, you can separate them from each other
using physical methods. The physical properties of one
substance are different from those of another. You can use
these differences to separate the substances. In contrast, you
can separate compounds only by a chemical change that
breaks the bonds between the elements.
6. Identify In what three
ways do compounds differ
from mixtures?
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Mixtures, Solubility, and Acid/Base Solutions
Reading Essentials
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Mixtures can be separated.
Mini Glossary
heterogeneous (he tuh roh JEE nee us) mixture: a
mixture in which substances are not evenly mixed
solution: a homogeneous mixture
substance: matter that is always made up of the same
homogeneous (hoh muh JEE nee us) mixture: a
combination of atoms
mixture in which two or more substances are evenly mixed
on the atomic level but not bonded together
mixture: two or more substances that are physically blended
but are not chemically bonded together
1. Review the terms and their definitions in the Mini Glossary. Write a sentence that
explains how a homogeneous mixture and a solution are related.
2. Complete the concept web by writing the types of matter in the correct boxes.
Matter
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
a.
mixtures
b.
c.
d.
e.
examples:
oxygen, carbon
examples:
water, sodium chloride
examples:
granite, blood
example:
air
What do you think
Reread the statements at the beginning of the
lesson. Fill in the After column with an A if you
agree with the statement or a D if you disagree.
Did you change your mind?
Reading Essentials
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Log on to ConnectED.mcgraw-hill.com
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lesson’s resources.
END OF
LESSON
Mixtures, Solubility, and Acid/Base Solutions
175