Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
26 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER
3
3.3 Mixtures of Matter
A mixture is a combination of two or more pure substances in
which each substance retains its individual properties. Concrete,
most rocks, most metal objects, all food, and the air you breathe are
mixtures that are often composed of many different substances. The
composition of a mixture is variable. For example, the composition
of salt water can be varied by changing the amount of salt or water
in the mixture.
Two types of mixtures exist. A heterogeneous mixture is one
that is not blended smoothly throughout. Examples of heterogeneous
mixtures include smoky air and muddy water. You may have to use a
magnifying glass or even a microscope, but if you can identify bits
of one or more of the components of a mixture, the mixture is heterogeneous.
A homogeneous mixture is one that has a constant composition
throughout. By dissolving sugar in water, you create a homogeneous
mixture. A homogeneous mixture is also called a solution. In solutions, the atoms and/or molecules of two or more substances are
completely mingled with one another. Solutions do not have to be
solids dissolved in liquids; they can be mixtures of various states of
matter. For example, air is a gaseous solution containing nitrogen,
oxygen, argon, carbon dioxide, water vapor, and small amounts of
other gases. An alloy is a homogeneous mixture (solution) of two or
more metals or of metals and nonmetals. Alloys are considered to be
solid solutions.
Practice Problems
8. Identify each of the following as an example of a homogeneous
mixture or a heterogeneous mixture.
a. 70% isopropyl rubbing alcohol
b. a pile of rusty iron filings
c. concrete
d. saltwater
e. gasoline
f. bread
26 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER
3
3.3 Mixtures of Matter
A mixture is a combination of two or more pure substances in
which each substance retains its individual properties. Concrete,
most rocks, most metal objects, all food, and the air you breathe are
mixtures that are often composed of many different substances. The
composition of a mixture is variable. For example, the composition
of salt water can be varied by changing the amount of salt or water
in the mixture.
Two types of mixtures exist. A heterogeneous mixture is one
that is not blended smoothly throughout. Examples of heterogeneous
mixtures include smoky air and muddy water. You may have to use a
magnifying glass or even a microscope, but if you can identify bits
of one or more of the components of a mixture, the mixture is heterogeneous.
A homogeneous mixture is one that has a constant composition
throughout. By dissolving sugar in water, you create a homogeneous
mixture. A homogeneous mixture is also called a solution. In solutions, the atoms and/or molecules of two or more substances are
completely mingled with one another. Solutions do not have to be
solids dissolved in liquids; they can be mixtures of various states of
matter. For example, air is a gaseous solution containing nitrogen,
oxygen, argon, carbon dioxide, water vapor, and small amounts of
other gases. An alloy is a homogeneous mixture (solution) of two or
more metals or of metals and nonmetals. Alloys are considered to be
solid solutions.
Practice Problems
8. Identify each of the following as an example of a homogeneous
mixture or a heterogeneous mixture.
a. 70% isopropyl rubbing alcohol
b. a pile of rusty iron filings
c. concrete
d. saltwater
e. gasoline
f. bread