Instructor’s Manual for Cracolice/Peters Introductory Chemistry: An Active Learning Approach, 8th Edition
CHAPTER 2
INSTRUCTOR’S MANUAL
Answers for Everyday Chemistry Quick Quiz Questions
1. A DNA fingerprint is a pattern of DNA fragments that is unique to an individual.
2. Some advantages include: Criminals can avoid leaving fingerprints at a crime scene; DNA can be
extracted from many sources other than fingertips, such as hair, blood, sweat, saliva, etc.; only a small
sample of biological material is needed; DNA fingerprinting can be used to identify non-human animals
and other organisms; etc.
Solutions for Black-Numbered Unanswered Problems
2. (a) Microscopic, (b) particulate, (c) macroscopic
4. Chemists use models, physical, virtual, mental, or some combination thereof, to represent the invisible
particles that make up matter.
6. Ice consists of water molecules that vibrate or shake in fixed positions relative to one another. The ice
has a fixed shape. When the ice melts, the molecules remain together but move freely among each other at
the bottom of the container that holds them, assuming the shape of the container bottom. As a gas, the
molecules separate, moving freely throughout a closed container or escaping into the atmosphere from an
open container.
8. The particles in a solid occupy fixed positions relative to each other and cannot be poured, but different
macroscopic pieces of solids can move relative to each other. The slogan emphasizes that this brand of
table salt has solid pieces small enough to move freely relative to one another, but not so small that they
stick together in humid weather.
10. Liquid volume is usually about the same as solid; gas volume is very much larger than liquid or solid.
12. (a) Chemical, (b) physical, (c) physical
14. (a) Chemical, (b) chemical, (c) physical
16. The change is chemical because the diatomic reactant molecules are transformed into monatomic
atoms.
2.1
,Instructor’s Manual for Cracolice/Peters Introductory Chemistry: An Active Learning Approach, 8th Edition
18. If both products are the same pure substance, they must be identical; thus, purchasing the half-priced
product is the better choice.
20. The photograph alone does not provide enough information to answer the question. You may know,
however, that dishwashing liquid is a mixture of water, detergent, and numerous other substances.
22. All are mixtures.
24. The object in (a) is a mixture because different substances are visible; (b) could be a pure substance in
two different states, but it is probably a mixture; (c) could be either a pure substance or a mixture because it
may be one kind of matter or two or more types of matter with similar appearances.
26. Yes—the terms homogeneous and heterogeneous refer to the macroscopic appearance and composition
of a sample. A container filled with liquid distilled water and ice made from it is heterogeneous in
appearance but is also pure, as long as in both phases the water is pure.
28. (a) Homogeneous, (b) heterogeneous, (c) homogeneous
30. The cylinder appears the same throughout, and it can be assumed that the percentage of each element is
constant throughout, so it is a homogeneous substance.
32. Your sketch should include two or more different types of particles mixed together (a mixture), evenly
distributed in the same phase of matter (so that it will appear homogeneous at the macroscopic level). Refer
to Figure 2.17.
34. Pick out plastic table tennis balls or steel bearing balls based on size and appearance; use magnetic
properties of steel to pick up bearing balls with a magnet; use the lower density of plastic and higher
density of steel to float the table tennis balls in water. These methods are based on physical properties.
36. Place the mixture in water. Salt will dissolve and sand will not. Filter out the sand. Evaporate the water
to obtain pure salt. Dissolving and recrystallizing the salt is a physical change because the salt did not
undergo a chemical change (you can taste the salt dissolved in the water, so it is still salt).
38. (a) Compound, (b) element, (c) element
40. (a) Element, (b) compound, (c) element
42. (a) Element, (b) neither element nor compound (not pure), (c) compound, (d) element, (e) element
44. (a) (1) Compound, (2) element, (3) elements, (4) compound, (5) compound. (b) In general, if there are
two or more words in the name, the substance is a compound. However, many compounds are known by
2.2
,Instructor’s Manual for Cracolice/Peters Introductory Chemistry: An Active Learning Approach, 8th Edition
one-word common names, and one-word names for many carbon-containing compounds are assembled
from prefixes, suffixes, and special names for recurring groups.
46. Only a compound with a certain taste can be decomposed into a gas and a solid having a different taste.
48. G, L, S P, M Hom, Het E, C
Limestone (calcium carbonate) S P Hom C
Lead S P Hom E
Freshly squeezed orange juice L&S M Het
Oxygen G P Hom E
Butter in the refrigerator S M Hom
50. (a) Attraction, (b) repulsion, (c) attraction
52. Products: H2O(g) and SO2(g). Reactants: H2S(g) and O2(g). Energy is transferred out of the chemical
system. The reaction is exothermic.
54. Product element: H2. Reactant compound: H2O.
56. (a) Exothermic, (b) exothermic, (c) endothermic
58. Kinetic energy increases.
60. The masses would be the same. Products of a chemical reaction have the same total mass as reactants.
62. Energy is transferred to plants from the sun. The amount of energy stored in a plant, mostly as
chemical energy, is equal to the amount of energy transferred to the plant as sunlight energy.
64. The potential energy of the water above the dam changes into kinetic energy as it falls into the turbine.
The turbine drives a generator in which kinetic energy is changed into the electrical energy that produces
the heat and light energy given off by the bulb.
68. Almost everything you use is either a result of or involves human-made chemical change in some way.
69. Almost everything you use is a mixture. Sugar is a rare example of a pure substance that you may have
used today.
70. Air, certainly, and perhaps tap water, and/or some glass or plastic products.
2.3
, Instructor’s Manual for Cracolice/Peters Introductory Chemistry: An Active Learning Approach, 8th Edition
84. Your illustration should resemble the phases in Figure 2.8. According to kinetic molecular theory,
particles move faster at higher temperatures, so particles are more likely to separate from one another at
higher temperatures.
2.4
CHAPTER 2
INSTRUCTOR’S MANUAL
Answers for Everyday Chemistry Quick Quiz Questions
1. A DNA fingerprint is a pattern of DNA fragments that is unique to an individual.
2. Some advantages include: Criminals can avoid leaving fingerprints at a crime scene; DNA can be
extracted from many sources other than fingertips, such as hair, blood, sweat, saliva, etc.; only a small
sample of biological material is needed; DNA fingerprinting can be used to identify non-human animals
and other organisms; etc.
Solutions for Black-Numbered Unanswered Problems
2. (a) Microscopic, (b) particulate, (c) macroscopic
4. Chemists use models, physical, virtual, mental, or some combination thereof, to represent the invisible
particles that make up matter.
6. Ice consists of water molecules that vibrate or shake in fixed positions relative to one another. The ice
has a fixed shape. When the ice melts, the molecules remain together but move freely among each other at
the bottom of the container that holds them, assuming the shape of the container bottom. As a gas, the
molecules separate, moving freely throughout a closed container or escaping into the atmosphere from an
open container.
8. The particles in a solid occupy fixed positions relative to each other and cannot be poured, but different
macroscopic pieces of solids can move relative to each other. The slogan emphasizes that this brand of
table salt has solid pieces small enough to move freely relative to one another, but not so small that they
stick together in humid weather.
10. Liquid volume is usually about the same as solid; gas volume is very much larger than liquid or solid.
12. (a) Chemical, (b) physical, (c) physical
14. (a) Chemical, (b) chemical, (c) physical
16. The change is chemical because the diatomic reactant molecules are transformed into monatomic
atoms.
2.1
,Instructor’s Manual for Cracolice/Peters Introductory Chemistry: An Active Learning Approach, 8th Edition
18. If both products are the same pure substance, they must be identical; thus, purchasing the half-priced
product is the better choice.
20. The photograph alone does not provide enough information to answer the question. You may know,
however, that dishwashing liquid is a mixture of water, detergent, and numerous other substances.
22. All are mixtures.
24. The object in (a) is a mixture because different substances are visible; (b) could be a pure substance in
two different states, but it is probably a mixture; (c) could be either a pure substance or a mixture because it
may be one kind of matter or two or more types of matter with similar appearances.
26. Yes—the terms homogeneous and heterogeneous refer to the macroscopic appearance and composition
of a sample. A container filled with liquid distilled water and ice made from it is heterogeneous in
appearance but is also pure, as long as in both phases the water is pure.
28. (a) Homogeneous, (b) heterogeneous, (c) homogeneous
30. The cylinder appears the same throughout, and it can be assumed that the percentage of each element is
constant throughout, so it is a homogeneous substance.
32. Your sketch should include two or more different types of particles mixed together (a mixture), evenly
distributed in the same phase of matter (so that it will appear homogeneous at the macroscopic level). Refer
to Figure 2.17.
34. Pick out plastic table tennis balls or steel bearing balls based on size and appearance; use magnetic
properties of steel to pick up bearing balls with a magnet; use the lower density of plastic and higher
density of steel to float the table tennis balls in water. These methods are based on physical properties.
36. Place the mixture in water. Salt will dissolve and sand will not. Filter out the sand. Evaporate the water
to obtain pure salt. Dissolving and recrystallizing the salt is a physical change because the salt did not
undergo a chemical change (you can taste the salt dissolved in the water, so it is still salt).
38. (a) Compound, (b) element, (c) element
40. (a) Element, (b) compound, (c) element
42. (a) Element, (b) neither element nor compound (not pure), (c) compound, (d) element, (e) element
44. (a) (1) Compound, (2) element, (3) elements, (4) compound, (5) compound. (b) In general, if there are
two or more words in the name, the substance is a compound. However, many compounds are known by
2.2
,Instructor’s Manual for Cracolice/Peters Introductory Chemistry: An Active Learning Approach, 8th Edition
one-word common names, and one-word names for many carbon-containing compounds are assembled
from prefixes, suffixes, and special names for recurring groups.
46. Only a compound with a certain taste can be decomposed into a gas and a solid having a different taste.
48. G, L, S P, M Hom, Het E, C
Limestone (calcium carbonate) S P Hom C
Lead S P Hom E
Freshly squeezed orange juice L&S M Het
Oxygen G P Hom E
Butter in the refrigerator S M Hom
50. (a) Attraction, (b) repulsion, (c) attraction
52. Products: H2O(g) and SO2(g). Reactants: H2S(g) and O2(g). Energy is transferred out of the chemical
system. The reaction is exothermic.
54. Product element: H2. Reactant compound: H2O.
56. (a) Exothermic, (b) exothermic, (c) endothermic
58. Kinetic energy increases.
60. The masses would be the same. Products of a chemical reaction have the same total mass as reactants.
62. Energy is transferred to plants from the sun. The amount of energy stored in a plant, mostly as
chemical energy, is equal to the amount of energy transferred to the plant as sunlight energy.
64. The potential energy of the water above the dam changes into kinetic energy as it falls into the turbine.
The turbine drives a generator in which kinetic energy is changed into the electrical energy that produces
the heat and light energy given off by the bulb.
68. Almost everything you use is either a result of or involves human-made chemical change in some way.
69. Almost everything you use is a mixture. Sugar is a rare example of a pure substance that you may have
used today.
70. Air, certainly, and perhaps tap water, and/or some glass or plastic products.
2.3
, Instructor’s Manual for Cracolice/Peters Introductory Chemistry: An Active Learning Approach, 8th Edition
84. Your illustration should resemble the phases in Figure 2.8. According to kinetic molecular theory,
particles move faster at higher temperatures, so particles are more likely to separate from one another at
higher temperatures.
2.4
