Solution Manual For Chemistry: An Atoms-Focused Approach, 3rd Edition

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iSOLUTIONS MANUALChemistry: An Atoms-FocusedApproachThird Edition

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ivContentsPrefaceChapter 1 | Matter and Energy: An Atomic PerspectiveChapter 2 | Atoms, Ions, and Molecules: The Building Blocks of MatterChapter 3 | Atomic Structure: Explaining the Properties of ElementsChapter 4 | Chemical Bonding: Understanding Climate ChangeChapter 5 | Bonding Theories: Explaining Molecular GeometryChapter 6 | Intermolecular Forces: Attractions between ParticlesChapter 7 | Stoichiometry: Mass Relationships and Chemical ReactionsChapter 8 | Reaction in Aqueous Solutions: Chemistry of the HydrosphereChapter 9 | Properties of Gases: The Air We BreatheChapter 10 | Thermochemistry: Energy Changes in Chemical ReactionsChapter 11 | Properties of Solutions: Their Concentrationsand Colligative PropertiesChapter 12 | Thermodynamics: Why Chemical Reactions HappenChapter 13 | Chemical Kinetics: Clearing the AirChapter 14 | Chemical Equilibrium: Equal but Opposite Reaction RatesChapter 15 | Acid–Base Equilibria: Proton Transfer in Biological SystemsChapter 16 | Additional Aqueous Equilibria: Chemistry and the OceansChapter 17 | Electrochemistry: The Quest for Clean EnergyChapter 18 | The Solid State: A Particulate ViewChapter 19 | Organic Chemistry: Fuels, Pharmaceuticals, and Modern MaterialsChapter 20 | Biochemistry: The Compounds of LifeChapter 21 | Nuclear Chemistry: The Risks and BenefitsChapter 22 | Main Group Elements: Life and the Periodic TableChapter 23 | Transition Metals: Biological and Medical ApplicationsProblem Correlation Table (Second to Third Edition)

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1CHAPTER 1 | Matter and Energy: An Atomic Perspective1.1.Collect and OrganizeFigure P1.1(a) shows “molecules,” each consisting of one red sphere and one blue sphere, and Figure P1.1(b)shows separate blue spheres and red spheres. For each image we are to identify the class of matter. We need todetermine whether the substance(s) depicted is/are solid, liquid, or gas and whether the images show an element,a compound, or a mixture that is homogeneous or heterogeneous.AnalyzeAn element is composed of all the same type of atom, and a compound is composed of two or more types of atoms.Solids have a definite volume and a highly ordered arrangement where the particles are close together. Liquidsalso have a definite volume but have a disordered arrangement of particles that are close together. Gases havedisordered particles that fill the volume of the container and are far apart from each other. Homogeneous mixtureshave a uniform distribution and composition, and heterogeneous mixtures contain regions of different composition.Solve(a)Because each particle in Figure P1.1(a) consists of one red sphere and one blue sphere, all the particles are thesame—that is a compound. The particles fill the container and are disordered, so those particles are in the gasphase.(b)Because it shows a mixture of red and blue spheres, Figure P1.1(b) depicts a mixture of blue elemental atomsand red elemental atoms. The blue spheres fill the container and are disordered, so those particles are in thegas phase. The red spheres have a definite volume and are ordered, so those particles are in the solid phase.This is a heterogeneous mixture.Think About ItRemember that both elements and compounds may be either pure or present in a mixture.1.2.Collect and OrganizeFigure P1.2(a) shows “atoms” of only red spheres, and Figure P1.2(b) has “molecules” consisting of two redspheres or two blue spheres. For each image we are to identify the class of matter. We need to determine whetherthe substance(s) depicted is/are solid, liquid, or gas and whether the images show an element, a compound, or amixture that is homogeneous or heterogeneous.AnalyzeA pure substance (whether element or compound) is composed of all the same type of molecule or atom, not amixture of two kinds. An element is composed of all the same type of atom, and a compound is composed of twoor more types of atoms. Solids have a definite volume and a highly ordered arrangement where the particles areclose together. Liquids also have a definite volume but have a disordered arrangement of particles that are closetogether. Gases have disordered particles that fill the volume of the container and are far apart from each other.Homogeneous mixtures have a uniform distribution and composition, and heterogenous mixtures contain regionsof different composition.Solve(a)Because all the atoms are of the same type, Figure P1.2(a) depicts a pure element. The particles take up adefinite volume and are ordered, so that element is in the solid phase.(b)Because it shows a mixture of blue diatomic molecules and red diatomic molecules, Figure P1.2(b) depicts amixture of two elements. Both the blue and red diatomic particles fill the container’s volume and are highlydisordered; the mixture depicted is in the gas phase. This is a homogeneous mixture.Think About ItElements do not need to be present as single atoms. They may be diatomic, as in H2or Br2, or even more highlyassociated, as in S8or P4.

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2|Chapter 11.3.Collect and OrganizeIn this question we are to consider whether the reactants, as depicted, undergo a chemical reaction and/or a phasechange.AnalyzeChemical reactions involve the breaking and making of bonds in which atoms are combined differently in theproducts than in the reactants. When we consider a possible phase change, remember the following: Solids have adefinite volume and a highly ordered arrangement where the particles are close together. Liquids also have adefinite volume but have a disordered arrangement of particles that are close together. Gases have disorderedparticles that fill the volume of the container and are far apart from one another.SolveIn Figure P1.3, two pure diatomic elements (red–red and blue–blue) in the gas phase recombine to form acompound (red–blue) in the solid phase (ordered array of molecules). Therefore, answer b describes the reactionshown.Think About ItA phase change does not necessarily accompany a chemical reaction. We will learn later that the polarity of theproduct will determine whether a substance will be in the solid, liquid, or gaseous state at a given temperature.1.4.Collect and OrganizeIn this question we are to consider whether the reactants, as depicted, undergo a chemical reaction (eitherrecombination or decomposition) and/or a phase change.AnalyzeChemical reactions involve the breaking and making of bonds in which atoms are combined differently in theproducts from how they are combined in the reactants. When we consider a possible phase change, remember thefollowing: Solids have a definite volume and a highly ordered arrangement where the particles are close together.Liquids also have a definite volume but have a disordered arrangement of particles that are close together. Gaseshave disordered particles that fill the volume of the container and are far apart from one another.SolveIn Figure P1.4 we see that no recombination of the diatomic molecules occurs. One pure diatomic element (red–red) condenses to a slightly disordered phase, whereas the other diatomic element (blue–blue) remains in the gasphase. Therefore, answer a describes the reaction pictured.Think About ItCooling of air to different temperatures in a controlled fashion separates the components of air.1.5.Collect and OrganizeFrom the diagram showing gaseous CO2at room temperature, we are to describe what the particulate image wouldbe after cooling this gas to 180 K.AnalyzeLooking up the information on the internet for carbon dioxide, CO2(g), we find that it has a sublimation temperatureof –78°C or 195 K. This temperature is higher than 180 K. Therefore, CO2at 180 K will be in the solid phase.SolveThe particulate image of CO2at 180 K will show the linear CO2molecules condensed at the bottom of the box onthe right with the molecules touching and forming a regular pattern.Think About ItSolid CO2is also known as dry ice, and at normal pressure (1 atm) the only phase change we observe is sublimation,not melting or boiling.

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Matter and Energy|31.6.Collect and OrganizeFrom the diagram showing a mixture of gaseous diatomic substances, we are to describe what the particulate imagewould be after cooling this mixture from 298 K to 70 K.AnalyzeUsing the atomic color palette on the inside back cover of the textbook, we can identify these three gases ashydrogen (white, H2), nitrogen (blue, N2), and oxygen (red, O2). From Appendix 3.2 we obtain the melting pointand boiling point for each of these gases: hydrogen (mp = –259.14°C, bp = –252.87°C), nitrogen (mp = –210.00°C,bp = –195.8°C), oxygen (mp = –218.8°C, bp = –182.95°C). We can then compare these to the temperature to whichwe are cooling the mixture, 70 K, which we can convert to kelvin through the following equation:(T)°C =T(K) – 273.15or(T)°C = 70 – 273.15 = –203°CSolveBecause 70 K or –203°C is higher than both the melting point and the boiling point of hydrogen, it is in the gasphase; the white diatomic molecules in the particulate picture will remain far apart and will be scattered in thevolume of the box. Because 70 K or –203°C is between the melting point and the boiling point of both nitrogenand oxygen, N2and O2will be in the liquid phase; the blue and red diatomic molecules in the particulate picturewill be condensed at the bottom of the box, but will not be lined up in any regular pattern, signifying that they arein the liquid state.Think About ItAt a temperature of, for example, –215°C or 58 K, the three gases will be in three different phases; hydrogen inthe gas phase, oxygen in the liquid phase, and nitrogen in the solid phase.1.7.Collect and OrganizeUsing the atomic color palette on the inside back cover of the textbook, we can identify these atoms in thesemolecules. Chemical formulas describe the type and number of atoms in a molecule.AnalyzeThe color palette identifies white atoms as hydrogen, red atoms as oxygen, black atoms as carbon, and green atomsas chlorine. To determine the chemical formula, we indicate the number of each type of atom as a subscript.Solve(a)CH2O(b)C2H6O2(c)CCl4Think About ItFor carbon-containing compounds, it is standard form to list the atoms in the following order: C, H, N, O.1.8.Collect and OrganizeUsing the atomic color palette on the inside back cover of the textbook, we can identify these atoms in thesemolecules. Chemical formulas describe the type and number of atoms in a molecule.AnalyzeThe color palette identifies white atoms as hydrogen, red atoms as oxygen, and black atoms as carbon. To determinethe chemical formula, we indicate the number of each type of atom as a subscript.Solve(a)C3H8O(b)C4H10O(c)C4H8O

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4|Chapter 1Think About ItFor these carbon-containing compounds, it is standard form to list the atoms in the following order: C, H, O.1.9.Collect and OrganizeGiven that the pill manufactured by a pharmaceutical company is to weigh 3.25 mg, we are asked to compare theprecision and accuracy of the data in the two graphs of masses of 4 pills.AnalyzePrecision in these pill samples means that the four pills have masses that do not vary much; accuracy in these pillsamples means that the four pills, on average, have a mass that is close to the desired mass of 3.25 mg.SolveThe graph for Sample A shows values that vary, but that are close to the desired value of 3.25 mg—this sample isaccurate but not precise. The graph for Sample B shows values that do not vary much, none of which is close tothe desired value of 3.25 mg—this sample isprecise but not accurate.Think About ItA sample that wasboth precise and accuratewould show all four pills close in value to each other and all veryclose to the desired mass of 3.25 mg.1.10.Collect and OrganizeFrom the representations [A] through [I] in Figure P1.10, we are to choose the one that contains the most atoms,contains the most elements, shows a solid solution, shows a homogeneous mixture, shows a compound, or showsan element.AnalyzeTo categorize the representations, we need to apply the definitions of atom, element, solid solution, homogeneousmixture, pure compound, and pure element. An atom is the smallest particle constituent that makes up matter; anelement is a substance composed of only one type of atom; a solid solution is a mixture of two or more substancesthat form a homogeneous solid; a homogeneous mixture is a mixture of elements or compounds that has uniformcomposition and properties; a pure compound is a substance made of different elements in a specific ratio; a pureelement is a substance made up of only one kind of atom with no other elements present in the substance.Solve(a)Of the representations, only [B], [F], [G], and [H] are molecules. Of those [B], glycine, contains 10 atoms;[F], ammonia, contains 4 atoms; [G], hydrogen peroxide, contains 4 atoms; and [H], propane, contains 11atoms. Therefore, [H], propane, contains the most atoms.(b)Of the representations, [B], [F], [G], and [H] are molecular representations of compounds. Of those [B],glycine, contains 4 elements (C, H, N, and O); [F], ammonia, contains 2 elements (N and H); [G], hydrogenperoxide, contains 2 elements (H and O); and [H], propane, contains 2 elements (C and H). Therefore, [B],glycine, contains the most elements.(c)[A], brass is a solid solution composed of copper and zinc.(d)[E] saline (dissolved NaCl in water) and [A] brass (a solid solution of copper and zinc) are homogeneousmixtures that have uniform composition and properties.(e)The pure substances in the list that are compounds are: [B] (glycine), [F] (ammonia), [G] (hydrogen peroxide),and [H] (propane).(f)The pure elements in the list are: [C] (helium), [D] (mercury), and [I] (platinum).Think About ItTechnically, by the broad definition, brass is a homogeneous mixture. However, for mixtures of metals or othersolids, we usually use the termsolid solutionto describe them. You might also find the termalloyused for a solidsolution of metal elements.1.11.Collect and OrganizeFor this question we are asked to differentiate “hypothesis” from “scientific theory.”

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Matter and Energy|5AnalyzeThese terms are part of the scientific method and result from different aspects of the process of observing andexplaining a natural phenomenon.SolveA hypothesis is a tentative explanation of an observation or set of observations, whereas a scientific theory is aconcise explanation of a natural phenomenon that has been extensively tested and explains why certain phenomenaare always observed.Think About ItNotice that a hypothesis might become a theory after much experimental testing.1.12.Collect, Organize,and AnalyzeIn this question we consider how a hypothesis becomes a theory.SolveA theory is formed from a hypothesis when the hypothesis has been extensively tested with many observations andexperiments. A theory is the best (current) possible explanation extensively supported by experimentation.Think About ItA theory, tested over time, may be elevated to become a scientific law.1.13.Collect and OrganizeIn this question we consider how Dalton’s atomic theory supported his law of multiple proportions.AnalyzeDalton’s law of multiple proportions states that when two elements combine to make two (or more) compounds,the ratio of the masses of one of the elements, which combine with a given mass of the second element, is alwaysa ratio of small whole numbers. His atomic theory states that matter in the form of elements and compounds ismade up of small, indivisible units—atoms.SolveDalton’s atomic theory explained the small, whole-number mass ratios in his law of multiple proportions becausethe compounds contained small, whole-number ratios of atoms of different elements per molecule or formula unit.Think About ItDalton’s theory is not strictly true. Atoms are divisible into electrons, protons, and neutrons (and even further intosubatomic quarks), and some compounds do not have whole-number ratios of atoms. For most matter and mostcompounds that we encounter in chemistry, though, his theory is true.1.14.Collect and OrganizeIn this question we are asked to explain why the existence of atoms in matter was considered a philosophy inancient Greece but had become a theory in the early 1800s.AnalyzeA philosophy is a set of beliefs arrived at through rational thought and not tested by experiment. A theory is formedfrom a hypothesis when the hypothesis has been extensively tested with many observations and experiments. Atheory is the best (current) possible explanation extensively supported by experimentation.SolveThe philosophy of the atom became the atomic theory in the 1800s when much of the experimental evidence thathad accumulated pointed to the particulate nature of matter. That mounting evidence changed the belief into atested best explanation for the nature of matter.

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6|Chapter 1Think About ItSome materials do not conform to the law of definite or constant proportions that led to the atomic theory. Anexample is a nonstoichiometric compound such as Fe0.95O, in which the proportions of the elements composingthe material can vary and the elements are not in strict whole-number proportions.1.15.Collect and OrganizeIn this question we are asked to explain why scientists opposed Proust’s law of definite proportions when heproposed it.AnalyzeThe law of definite proportions states that the ratio of elements in a compound is always the same.SolveProust’s law needed to have corroborating evidence to fully support it. At the time, experiments to prepare acompound of tin with oxygen yielded various compositions. The compounds they prepared, when analyzed later,turned out to be mixtures of two compounds of tin oxide.Think About ItTin can form either tin(II) oxide, SnO, or tin(IV) oxide, SnO2. What do you think the ratio of the elements wouldbe for a 50–50 mixture of these two compounds? Of a 25–75 mixture?1.16.Collect and OrganizeFor this question we are asked to describe a chemical reaction that illustrates Dalton’s law of multiple proportions.AnalyzeDalton’s law of multiple proportions states thatwhen two elements combine to make two (or more) compounds,the ratio of the masses of one of the elements, which combine with a given mass of the second element, isalways a ratio of small whole numbers.SolveThe law of multiple proportions can be illustrated for any combination of two elements that can give twocompounds. One example is the reaction of carbon with oxygen to give either carbon monoxide, CO, orcarbon dioxide, CO2.C(s) + ½ O2(g)®CO(g)C(s) + O2(g)®CO2(g)Think About ItOther examples of this are: nitrogen reacting with oxygen to give various NOxspecies like NO, NO2, N2O, N2O5,and several others; and sulfur reacting with oxygen to give SO2, SO3, S2O, S2O2, and several others.1.17.Collect and OrganizeWe are to definetheoryas used in everyday conversation and differentiate it from its use in science.AnalyzeTheoryin everyday conversation has a quite different meaning from its meaning in science.SolveWhereastheoryin normal conversation means someone’s idea or opinion that is open to speculation, a scientifictheory is a concise and testable explanation of natural phenomena based on observation and experimentation thatcan accurately predict the results of experiments.Think About ItTheoryin normal conversation is more akin to ahypothesisor aguessthat may or may not be testable.

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Matter and Energy|71.18.Collect and OrganizeWe are asked to give an example of a scientific theory that accurately predicted the results of an experiment beforeit was carried out.AnalyzeA theory is a concise and testable explanation of natural phenomena based on observation and experimentation.There are many examples in science where theory predicted the results of an experiment first.SolveAnswers may vary, but you might give this as a chemistry example: Mendeleev’s formulation of the periodic tablepredicted the existence of elements such as gallium and germanium and predicted their physical properties such asdensities, melting points, and boiling points along with their chemical reactivities.Think About ItMore recent examples include the prediction of the existence of gravitational waves (LIGO Lab) and the predictionof the existence and properties of the Higgs boson.1.19.Collect and OrganizeWe are asked to consider whether a scientific hypothesis can be disproven.AnalyzeA scientific hypothesis is a testable, yet tentative, explanation for an observation (or set of observations) in thenatural world.SolveYou can disprove a scientific hypothesis through an experiment that does not give the predicted outcome.Think About ItAn important feature of scientific inquiry that distinguishes it from other forms of inquiry is that the hypothesesare testable and that failure results in a reexamination of the hypotheses.1.20.Collect and OrganizeWe consider in this question whether a theory can be proven.AnalyzeIn science, a theory is the best (current) possible explanation extensively supported by experimentation andobservations.SolveTheoryis nearly equivalent tofactin science, without being the absolute truth. A theory is hard to prove absolutelybut has many, many supporting experiments whose observations strongly support it.Think About ItOne experiment that is counter to the explanation for a phenomenon that the theory explains could disprove atheory, so theories may be toppled and replaced with new explanations and theories.1.21.Collect and OrganizeFor the foods listed, we are to determine which are heterogeneous mixtures.AnalyzeA heterogeneous mixture has visible regions of different composition.SolveClear regions of different composition are evident in a Snickers bar (b) and in an uncooked hamburger (d), but notin bottled water (a) or in grape juice (c).

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8|Chapter 1Think About ItBottled water contains a homogeneous mixture of water and small amounts of dissolved minerals such as salts ofsodium, magnesium, and calcium that give the water its flavor.1.22.Collect and OrganizeFor the foods listed, we are to determine which are homogeneous.AnalyzeHomogeneous mixtures have the same composition throughout.SolveFreshly brewed coffee and vinegar (a, b) are homogeneous mixtures. A slice of white bread and a slice of ham (c,d) are heterogeneous mixtures.Think About ItA slice of white bread is considered heterogeneous because its crust is different from the interior bread, and thebread contains gas bubbles that are clearly seen as tiny holes. If the coffee contains unfiltered sediment or thevinegar contains remnants of the mother of vinegar (a cellulose disc containing acetic acid bacteria added to analcohol to change it into vinegar), then it would be considered a heterogeneous mixture.1.23.Collect and OrganizeFor the foods listed, we are to determine which are heterogeneous.AnalyzeA heterogeneous mixture has visible regions of different composition.SolveDistinct regions of different composition are evident in orange juice (with pulp) (d) and tomato juice (e), but notin apple juice, cooking oil, or solid butter (a–c).Think About ItWhen butter melts, you notice milk solids and clear regions that are definitely discernible. Therefore, homogeneoussolid butter becomes heterogeneous when heated.1.24.Collect and OrganizeFor the substances listed, we are to determine which are homogeneous.AnalyzeHomogeneous mixtures have the same composition throughout.SolveSweat, gasoline, and compressed air in a scuba tank (b, d, and e) are homogeneous.Think About ItNile River water (c) and a piece of wood (a) are heterogeneous because they have distinct regions that arediscernible. Nile River water contains sediment and there is visible uneven distribution of heartwood and knots,for example, in a piece of wood.1.25.Collect and OrganizeWe are asked to consider whether distillation would be effective in removing suspended soil particles from water.AnalyzeIn distillation, evaporation of a liquid and subsequent condensation of the vapor is used to separate substances ofdifferent volatilities.

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Matter and Energy|9SolveSoil particles are not volatile, but water is; we can boil water, but not the soil. Therefore, yes, distillation can beused to remove soil particles from water. It is not a widely used process to purify water because boiling water isenergy- and time-intensive. Filtration would be both cheaper and faster than distillation.Think About ItIn this distillation process we would collect pure water through condensation, and the soil particles would be leftbehind in the distillation flask.1.26.Collect and OrganizeReferring to Figure 1.8(b) in the textbook, we are to decide which compounds interact more strongly with thestationary phase on the basis of their relative positions as the liquid phase migrates up the solid phase in achromatography experiment.AnalyzeIn chromatography, a mixture of dissolved substances is placed on a solid stationary phase and a mobile phase(solvent) is used to separate the components. Substances that have more affinity for the stationary phase and lessfor the mobile phase move more slowly.SolveThe yellow-colored compounds at the bottom bind more tightly with the stationary phase than the green ones orthe yellow ones at the top; they did not move as far up the stationary phase with the mobile phase.Think About ItFigure 1.8(b) shows just one kind of chromatography method, namely, paper chromatography on paper. Otherexamples include gas chromatography, ion exchange chromatography, and liquid chromatography, but they alloperate on the same principle of the substances in the mixture having different affinities for the stationary andmobile phases.1.27.Collect and OrganizeFor this question we are to list some chemical and physical properties of gold.AnalyzeA chemical property is seen when a substance undergoes a chemical reaction or is resistant to reaction with anothersubstance. A physical property can be seen without any transformation of one substance into another.SolveOne chemical property of gold is its resistance to corrosion (oxidation). Gold’s physical properties include itsdensity, color, melting temperature, and electrical and thermal conductivity.Think About ItAnother metal that does not corrode (or rust) is platinum. Platinum and gold, along with palladium, are often callednoble metals.1.28.Collect and OrganizeFor this question we are to compare the physical properties of gold and silver.AnalyzePhysical properties include color, metallic luster, malleability, ductility, melting point, boiling point, density,electrical conductivity, and thermal conductivity.SolveBoth gold and silver have metallic luster, are malleable, and conduct electricity. However, gold and silver havedifferent densities, different melting temperatures, and different colors.

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10|Chapter 1Think About ItThe yellow color of pure gold, compared with most metals, which are silvery, is the result of relativistic effects inthe atom.1.29.Collect and OrganizeWe are asked in this question to name three properties to distinguish among table sugar, water, and oxygen.AnalyzeWe can distinguish among substances by using either physical properties (such as color, melting point, and density)or chemical properties (such as chemical reactions, corrosion, and flammability).SolveWe can distinguish among table sugar, water, and oxygen by examining their physical states (sugar is a solid, wateris a liquid, and oxygen is a gas at normal temperatures and pressures) and by their densities, melting points, andboiling points.Think About ItThese three substances are also very different at the atomic level. Oxygen (O2) is a pure element made up ofdiatomic molecules; water is a compound made up of discrete molecules composed of hydrogen and oxygen atoms(H2O); and table sugar is a solid compound made up of carbon, hydrogen, and oxygen atoms.1.30.Collect and OrganizeWe are asked in this question to name three properties to distinguish among table salt, sand, and copper.AnalyzeWe can distinguish among substances by using either physical properties (such as color, melting point, and density)or chemical properties (such as chemical reactions, corrosion, and flammability).SolveWe can distinguish among table salt, sand, and copper by examining their color (salt is composed of small cubicwhite crystals, sand is irregularly shaped and many-colored, and copper is a reddish metal). Salt will dissolve inwater, whereas sand and copper will not. Copper conducts electricity, whereas solid table salt and sand do not. Thedensities of these substances also will differ.Think About ItThese three substances are also very different at the atomic level. Table salt is a crystalline ionic solid composedof sodium cations and chloride anions. Sand is a covalent network solid most commonly composed of silica, acompound of silicon and oxygen. Copper is a pure element and a metallic crystal.1.31.Collect and OrganizeFrom the list of properties of sodium, we are to determine which are physical and which are chemical properties.AnalyzePhysical properties are those that can be observed without transforming the substance into another substance.Chemical properties are observed only when one substance reacts with another and therefore is transformed intoanother substance.SolveDensity, melting point, thermal and electrical conductivity, and softness (a–d) are all physical properties, whereastarnishing and reaction with water (e and f) are both chemical properties.Think About ItBecause the density of sodium is less than that of water, a piece of sodium will float on water as it reacts. Becausesodium is more dense than kerosene, with which it does not react chemically, Na can, with great care, be stored inthe lab in a container under kerosene.

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Matter and Energy|111.32.Collect and OrganizeFrom the list of properties of hydrogen gas, we are to determine which are physical and which are chemicalproperties.AnalyzePhysical properties are those that can be observed without transforming the substance into another substance.Chemical properties are observed only when one substance reacts with another and therefore is transformed intoanother substance.SolveDensity, boiling point, and electrical conductivity (a, c, and d) are all physical properties, whereas the reaction ofhydrogen with oxygen (b) is a chemical property.Think About ItBecause the density of hydrogen gas is lower than that of any other gas, a lightweight balloon filled with hydrogenwill float in air like the more familiar helium balloon.1.33.Collect and OrganizeWe are to explain whether an extensive property can be used to identify a substance.AnalyzeAn extensive property is one that, like mass, length, and volume, is determined by size or amount.SolveExtensive properties will change with the size of the sample and therefore cannot be used to identify a substance.Think About ItWe could, for example, have the same mass of feathers and lead, but their mass alone will not tell us which massmeasurement belongs to which—the feathers or the lead.1.34.Collect and OrganizeOf the properties listed, we are to choose which are intensive properties.AnalyzeAn intensive property does not depend on the size or amount of the sample.SolveOf the properties on the list, freezing point (a) and temperature (c) are intensive properties. Heat content (b)depends on sample size and is therefore an extensive property.Think About ItIntensive properties are related to chemical interactions between atoms and molecules in the substance.1.35.Collect and OrganizeWe are to explain whether the extinguishing of fires by carbon dioxide, CO2, is a result of its chemical or physicalproperties (or both).AnalyzePhysical properties are those that can be observed without transforming the substance into another substance.Chemical properties are observed only when one substance reacts with another and therefore is transformed intoanother substance.SolveCarbon dioxide is a nonflammable gas (a chemical property; it does not burn) and it is more dense than air (aphysical property; it smothers the flames by excluding oxygen from the fuel). Therefore, CO2’s fire-extinguishingproperties are due to both its physical and its chemical properties.

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12|Chapter 1Think About ItSome metals, such as magnesium, will burn in carbon dioxide; those fires cannot be extinguished with a CO2fireextinguisher.1.36.Collect and OrganizeWe are to explain whether the resistance of stainless steel to corrosion is a result of its chemical or physicalproperties.AnalyzePhysical properties are those that can be observed without transforming the substance into another substance.Chemical properties are observed only when one substance reacts with another and therefore is transformed intoanother substance.SolveCorrosion is the chemical reaction of a metal with a substance such as oxygen, and so the lower reactivity ofstainless steel must then derive from its chemical properties.Think About ItStainless steel contains chromium, which forms a passive layer of chromium oxide on the surface to protect theiron in the steel from contacting oxygen-containing air and then rusting.1.37.Collect and OrganizeWe are asked to compare the arrangement of water molecules in water as a solid (ice) and in water as a liquid.AnalyzeFigure A1.37 shows the arrangement of the water molecules in both those phases.Figure A1.37SolveWater molecules in both the ice and liquid forms contain interactions that link individual molecules closelytogether. The arrangement of the molecules in liquid water have no long-range structure or ordering, whereas inice the molecules are arranged in a rigid hexagonal arrangement with voids within the structure.Think About ItThe structure of ice is more open than the structure of liquid water. That is why, when water freezes, it expands.1.38.Collect and OrganizeWe are asked to describe what occupies the space between the molecules of a gas.AnalyzeA gas consists of particles (atoms or molecules) that are far apart from each other.SolveNothing (no other atoms or molecules) exists in the space between particles in a gas.

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Matter and Energy|13Think About ItBecause a gas consists of a lot of empty space, most gases are highly compressible.1.39.Collect and OrganizeWe are to determine which phase (solid, liquid, or gas–all of which are present at thetriple point) has the greatestparticle motion and which has the least.AnalyzeGases have particles much separated from each other; these particles, therefore, have a wide range of movement(more degrees of freedom). Particles in solids and liquids are close to one another, and therefore the particle motionin both phases is restricted. Solids hold their particles in rigid arrays.SolveBecause of their freedom of movement, gases have the greatest particle motion; because of the restriction of theirsolid lattice, solids have the least particle motion.Think About ItHeating a solid or liquid can melt or vaporize a substance. During these phase changes with the addition of heat,particle motion increases.1.40.Collect and OrganizeWe are to identify the chemical nature of the gas inside the bubbles in boiling water.AnalyzeHeating a substance increases the molecules’ motion. If enough heat is added, the molecules may undergo a phasechange.SolveIn boiling water, the liquid water is undergoing a phase change to water vapor. The bubbles are composed ofgaseous water.Think About ItThe energy required to boil water is not enough energy to break the H—O bonds in water. Therefore, at water’sboiling point, the bubbles do not contain hydrogen and oxygen gas from the decomposition of water. Water vapor,also known as steam, is invisible; the “steam” seen around hot drinks on cold days results from droplets of liquidwater that condensed as the vapor cooled.

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