Download AP Chemistry - Problem Drill 03: Matter and Energy Question No. 1

AP Chemistry - Problem Drill 03: Matter and Energy
Question No. 1 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
1. Which of the following is a pure substance?
Question
(A)
(B)
(C)
(D)
(E)
Air
Brass
Tap water
Carbon Dioxide
Salt Water
A. Incorrect!
Air appears to be the same throughout…but air contains various atoms, molecules,
and particles Gases such as oxygen, carbon dioxide and hydrogen, as well as fine
particles are all included in “air.” Air is a homogeneous mixture, not a pure
substance.
B. Incorrect!
Brass appears uniform. This may be a difficult decision for you if you are not aware
of the components of brass. It is a mixture of copper and zinc. Since it is a
mixture of more than one element that is chemically bonded, it is therefore a
homogeneous mixture and not a pure substance.
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C. Incorrect!
Tap water appears to be the same throughout. However, there are many
components in tap water (fluoride for teeth, chlorine to kill bacteria, rust from
pipes, etc.) Therefore, tap water is a homogeneous mixture and not a pure
substance.
D. Correct!
Carbon dioxide is a chemical compound—one carbon and two oxygen atoms are
bonded together.
Therefore, it is a pure substance.
E. Incorrect!
Salt water looks the same throughout. However, it is composed of salt dissolved in
water. Therefore there is more than one type of matter present. It is a
homogeneous mixture which means it is not a pure substance.
Carbon dioxide is a chemical compound—one carbon and two oxygen atoms are
bonded together. Therefore, it is a pure substance.
The rest of the options look like pure substances but are all homogeneous mixtures.
The correct answer is (D).
Solution
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Question No. 2 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
2. Which of the following is a heterogeneous mixture?
Question
(A)
(B)
(C)
(D)
(E)
Table salt
Pop
Air
Steel
Brass
A. Incorrect!
Table salt (NaCl, sodium chloride) is two elements chemically bonded together.
Therefore it is a compound. Compounds are pure substances and therefore it is not
a heterogeneous mixture.
B. Correct!
Pop is a mixture of sugars, flavors, water, caffeine, carbon dioxide, etc. The carbon
dioxide is in gaseous form, causing bubbles. Since the mixture has a liquid portion
and a gaseous portion (the bubbles), it is a heterogeneous mixture.
C. Incorrect!
Air is a mixture of various gases (oxygen, hydrogen, carbon dioxide, etc.) and small
air particles. These various types of matter are not visible. Therefore, air is a
homogeneous mixture…not a heterogeneous one.
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D. Incorrect!
Steel is a mixture of carbon and iron. However, the two types of elements are not
visible in the finished product. Therefore it is a homogeneous mixture, not a
heterogeneous one.
E. Incorrect!
Brass is a mixture of copper and zinc. However, the two types of elements are not
visible in the finished product. Therefore it is a homogeneous mixture, not a
heterogeneous one.
The carbon dioxide is in gaseous form, causing bubbles. Since pop has a liquid
portion and a gaseous portion (the bubbles), it is a heterogeneous mixture.
All of the other options are homogeneous mixtures—they are composed of more
than one thing but they look like one thing.
The correct answer is (B).
Solution
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Question No. 3 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
3. Which of the following is not a common sign of a chemical change?
Question
(A)
(B)
(C)
(D)
(E)
Bubbles
Light given off
Solution getting warm
Precipitate forming
A solid melting
A. Incorrect!
Bubbles indicate that a gas is being formed. This is a common indicator of a
chemical change. (However, it can accompany physical changes as well, such as
during boiling or pressure changes with a solution containing a dissolved gas).
B. Incorrect!
Light being given off is a common indicator of a chemical change.
C. Incorrect!
An energy (temperature) change is a common indicator of chemical changes.
(Although energy changes can accompany physical changes as well, such as phase
changes or dissolving).
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D. Incorrect!
A precipitate is an insoluble compound that forms after combining two solutions
(made for soluble compounds). Therefore, a new substance is made (one that is
insoluble). This is a chemical change.
E. Correct!
Melting is a physical change from a “solid phase” to a “liquid phase”. Therefore, a
solid melting is not a sign of a chemical change.
Although there are signs that can signify a chemical change—you must be careful.
Some of these signs can also be present in a physical change. To determine for
sure, you could test various properties of the final sample and compare them to the
original sample. If the sample now has many different properties or components
then it was a chemical change.
The correct answer is (E).
Solution
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Question No. 4 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
4. What type of statement is the following: “The Alkaseltzer will react with the
water faster if the tablet is crushed.”
Question
(A)
(B)
(C)
(D)
(E)
Prediction
Law
Hypothesis
Theory
Idea
A. Correct!
A prediction does not attempt to explain why—it simply predicts what will happen.
This statement is a prediction.
B. Incorrect!
A law describes natural phenomena which can occasionally be approximated by a
mathematical expression.
C. Incorrect!
A hypothesis includes a prediction and an attempt to explain why. This statement
is just a prediction.
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D. Incorrect!
A theory attempts to explain why phenomenon occurs the way that it does.
E. Incorrect!
Although this statement may be considered an idea, in science we refer to it as a
prediction.
Theories and hypothesis attempt to explain why phenomenon occurs the way that it
does. This statement does not include any form of explanation. A law describes
natural phenomena, usually with math. This statement is a prediction.
The correct answer is (A).
Solution
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Question No. 5 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
5. Which of the following is a valid reason for why making Kool-ade is a physical
change?
Question
(A) A color change is seen.
(B) The dry ingredients that are added to the water can be acquired again by
evaporating the water.
(C) It makes a homogeneous mixture.
(D) There is no temperature change.
(E) The dry ingredients disappear.
A. Incorrect!
A color change is a common sign of a chemical change; therefore it does not prove
that this is a physical change.
B. Correct!
Evaporating water is a physical change. If a physical change can un-do a previous
change, then the previous change must have been physical as well. Therefore, this
is a valid argument for this change being physical.
C. Incorrect!
Many chemical processes also make homogeneous mixtures; therefore this is not
proof that this change is physical.
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D. Incorrect!
Although temperature changes are often common in chemical changes, not all
chemical changes result in a temperature change. Therefore, the lack of a
significant temperature change is not proof that the change is physical.
E. Incorrect!
The dry ingredients do not disappear; they spread out when they are dissolved until
the naked eye cannot detect them.
Color changes and temperature changes are often signs of chemical changes, but
they are not proof one way or another. Evaporating water is a physical change. If
a physical change can un-do a previous change, then the previous change must
have been physical as well. Therefore, this is a valid argument for this change
being physical.
The correct answer is (B).
Solution
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Question No. 6 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
6. Which of the following is not a physical change?
Question
(A)
(B)
(C)
(D)
(E)
Melting
Drying
Evaporating
Burning
Boiling
A. Incorrect!
Melting is a physical change from solid to liquid.
B. Incorrect!
Drying, boiling and evaporating are all physical changes from liquid to gas.
C. Incorrect!
Drying, boiling and evaporating are all physical changes from liquid to gas.
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D. Correct!
Burning is a chemical change (combustion).
E. Incorrect!
Drying, boiling and evaporating are all physical changes from liquid to gas.
Melting is a physical change from solid to liquid. Drying, boiling and evaporating
are all physical changes from liquid to gas. Burning is a chemical change.
The correct answer is (D).
Solution
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Question No. 7 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
7. Which of the following is a mixture?
Question
(A)
(B)
(C)
(D)
(E)
Ice and water
Aluminum oxide
Table salt (sodium chloride)
Liquid mercury
Gold foil
A. Correct!
Even though ice and water are both H2O, it is considered a mixture because there is
more than one “state” together.
B. Incorrect!
Aluminum and oxygen bonded together form aluminum oxide. It is a compound
and compounds are not mixtures.
C. Incorrect!
Sodium chloride is sodium and chloride bonded together. It is a compound and
compounds are not mixtures.
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D. Incorrect!
Liquid mercury is an element. Elements are not mixtures.
E. Incorrect!
Gold foil contains only gold atoms. Elements are not mixtures.
Aluminum oxide and sodium chloride are compounds, which are not mixtures.
Mercury and gold are elements, which are not mixtures. Ice and water, although
both H2O, are different states of matter and therefore are a mixture when together.
The correct answer is (A).
Solution
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Question No. 8 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
8. Which of the following is a pure substance?
Question
(A)
(B)
(C)
(D)
(E)
Tap water
Granite
Air
Deoxyribonucleic acid (DNA)
Wood
A. Incorrect!
Tap water often looks pure, however it has many dissolved substances, such as
chlorine and fluoride. Therefore it is a mixture.
B. Incorrect!
Granite has different flakes and chunks of various colors and rock. Therefore it is a
heterogeneous mixture, and not a pure substance.
C. Incorrect!
Air looks pure, however it is a mixture of oxygen, hydrogen, carbon dioxide, that
are not chemically bonded together.
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D. Correct!
DNA is a molecule—it is a pure substance.
E. Incorrect!
Wood is a heterogeneous mixture of many types of molecules.
Tap water and air may look like a pure substance, but they are homogeneous
mixtures. Wood and granite are heterogeneous mixtures. DNA is a molecule and
is therefore a pure substance.
The correct answer is (D).
Solution
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Question No. 9 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
9. Which type of matter can be separated chemically but not physically?
Question
(A)
(B)
(C)
(D)
(E)
Elements
Compounds
Heterogeneous mixtures
Homogeneous mixtures
Solutions
A. Incorrect!
Elements cannot be separated physically or chemically.
B. Correct!
Compounds can be separated chemically but not physically.
C. Incorrect!
All types of heterogenous mixtures can be separated physically.
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D. Incorrect!
All types of homogenous mixtures can be separated physically.
E. Incorrect!
All types of solutions can be separated physically, for instance, the distillation of
alcohol.
Elements cannot be separated chemically or physically. All types of mixtures can
be separated physically. Compounds can be separated chemically but not
physically.
The correct answer is (B).
Solution
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Question No. 10 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
10. Which of the following is a physical change?
Question
(A)
(B)
(C)
(D)
(E)
Burning
Oxidizing
Rusting
Boiling
Decomposing
A. Incorrect!
Burning is a chemical change.
B. Incorrect!
Oxidizing is a chemical change.
C. Incorrect!
Rusting is the oxidizing of iron, which is a chemical change.
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D. Correct!
Boiling is the physical change from a “liquid phase” to a “gas phase”.
E. Incorrect!
Decomposing is the chemical breaking down of a substance.
Burning, oxidizing, rusting and decomposing are chemical processes while boiling is
a physical change from liquid to gas.
The correct answer is (D).
Solution
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