CHAPTER 3 Matter—Properties and Changes - irion-isd.org · PDF file54 Chapter 3 What You’ll Learn You will distinguish between physical and chemical properties. You will classify

54A

Section 3.2Changes in Matter1 session

1/2 block

P

LS

Section 3.3Mixtures of Matter2 sessions

1 block

P

LS

1. Identify the characteristics of asubstance.

2. Distinguish between physical andchemical properties.

3. Differentiate among the physicalstates of matter.

4. Define physical change and list severalcommon physical changes.

5. Define chemical change and listseveral indications that a chemicalchange has taken place.

6. Apply the law of conservation of massto chemical reactions.

7. Contrast mixtures and substances.8. Classify mixtures as homogeneous

or heterogeneous.9. List and describe several techniques

used to separate mixtures.

Discovery Lab: Observing ChemicalChange, p. 55Careers Using Chemistry: Science Writer,p. 56Problem-Solving Lab: How is compressedgas released? p. 60

ChemLab: Matter and Chemical Reactions,pp. 78–79

MiniLab: Separating Ink Dyes, p. 68

Section 3.4Elements andCompounds2 sessions

1 block

P

LS

10. Distinguish between elements andcompounds.

11. Describe the organization of elementson the periodic table.

12. Explain how all compounds obey thelaws of definite and multipleproportions.

History Connection, p. 75Chemistry and Society: Green Buildings,p. 80

Section Objectives Activities/Features

CHAPTER Matter—Properties and Changes

Section 3.1Properties of Matter1 session

1/2 block

P

LS

3

Resource Manager

54B

CHAPTER 3 RESOURCE MANAGER

UCP.1, UCP.2, UCP.3;A.1; B.2, B.3, B.4, B.5,B.6;G.1

1(A), 2(A), 2(D), 3(D),4(A), 4(B), 4(C), 5(A)

UCP.1, UCP.2, UCP.3;B.2, B.3, B.5, B.6

2(C), 4(B), 5(A), 5(C)

UCP.1, UCP.2, UCP.3;A.1; B.2; E.1

1(A), 4(C)

UCP.1, UCP.2, UCP.3;A.1; B.1, B.2, B.3, B.6;E.2; F.4, F.6; G.1, G.2,G.3

1(A), 2(A), 2(B), 2(C),2(D), 2(E), 3(B), 3(C),3(E), 4(A), 4(B), 4(C),4(D), 5(A), 6(C), 11(A)

National Science State/Local Reproducible Masters TransparenciesContent Standards Standards

Study Guide for Content Mastery,p. 16 ChemLab and MiniLabWorksheets, p. 9 Forensics Laboratory Manual,pp. 1–12 Small-Scale Laboratory Manual,pp. 9–12 L2

P

LS

L2

P

LS

L2

P

LS

L2

P

LS

Section Focus Transparency 11

P

ELL

LS

L1

P

LS

Study Guide for Content Mastery,pp. 17–18 ChemLab and MiniLabWorksheets, pp. 10–12 L2

P

LS

L2

P

LS


Teaching Transparencies 9, 10

Math Skills Transparency 3

P

ELL

LS

L2

P

LS

P

ELL

LS

L2

P

LS

P

ELL

LS

L1

P

LS

Study Guide for Content Mastery,pp. 13–14 Laboratory Manual,pp. 17–20 Small-Scale Laboratory Manual,pp. 5–8 L2

P

LS

L2

P

LS

L2

P

LS


Teaching Transparency 7

P

ELL

LS

L2

P

LS

P

ELL

LS

L1

P

LS

Study Guide for Content Mastery,p. 15 ChemLab and MiniLabWorksheets, pp. 10–12 Challenge Problems, p. 3 Laboratory Manual,pp. 21–24 L2

P

LS

L3

P

LS

L2

P

LS

L2

P

LS


Teaching Transparency 8

Math SkillsTransparency 2

P

ELL

LS

L2

P

LS

P

ELL

LS

L2

P

LS

P

ELL

LS

L1

P

LS

Key to National Science Content Standards: UCP � Unifying Concepts andProcesses, A � Science as Inquiry, B � Physical Science, C � Life Science,D � Earth and Space Sciences, E � Science and Technology,F � Science in Personal and Social Perspectives, G � History and Nature of Science

Refer to pages 4T–5T of the Teacher Guide for an explanation of the National Science Content Standards correlations.

54C

ChemLab (pages 78–79)copper wire, AgNO3 solution, sandpaper, stirring rod, 50-mL graduated cylinder, 50-mL beaker,funnel, filter paper, 250-mL Erlenmeyer flask, ring stand, small iron ring, petri dish, paper clip,Bunsen burner, tongs

Discovery Lab (page 55)test tube, test-tube rack, 3M hydrochloric acid (10 mL), zinc metal, wood splint, burner

MiniLab (page 68)9-oz. plastic cup (2), filter paper (2), scissors, water-soluble black felt marker, large nail, water

Demonstration (pages 62–63)piece of zinc (2 g), NaOH (5 g), porcelain evaporating dish, forceps, paper towel, hot plate, newpennies (3), water

For a review of solution preparation, see page 46T of the Teacher Guide.

Quantities are for a class of 30 students.

ChemLab (pages 78–79)1M silver nitrate (AgNO3) Dissolve 170 g AgNO3 in 600 mL distilled water. Make up to 1 L

final volume with distilled water. CAUTION: Silver nitrate is toxic and harmful to skin and clothing.

Discovery Lab (page 55)3M hydrochloric acid Add 100 mL concentrated (12M) hydrochloric acid to 300 mL distilled

water while stirring. CAUTION: Do NOT add the water to the acid.

Chapter Assessment, pp. 13–18MindJogger VideoquizzesAlternate Assessment in the Science ClassroomTestCheck Software Solutions Manual, Chapter 3Supplemental Problems, Chapter 3Performance Assessment in the Science ClassroomChemistry Interactive CD-ROM, Chapter 3 quiz

Spanish Resources Guided Reading Audio Program, Chapter 3Cooperative Learning in the Science ClassroomLab and Safety Skills in the Science ClassroomLesson PlansBlock Scheduling Lesson Plans

P

ELL

LS

P

ELL

LS

Materials List

Preparation of Solutions

Assessment Resources Additional Resources

CHAPTER Matter—Properties and Changes3

Resource Manager

Texas Lesson PlansTexas Block Scheduling Lesson Plans

54D

Level 1 activities should be appropriate for students withlearning difficulties.

Level 2 activities should be within the ability range of all students.

Level 3 activities are designed for above-average students.

ELL activities should be within the ability range ofEnglish Language Learners.

Cooperative Learning activities are designedfor small group work.

These strategies represent student products that can beplaced into a best-work portfolio.

These strategies are useful in a block scheduling format.

P

LS

PP

LS

P

COOP LEARN

LS

P

ELL

LS

L3

P

LS

L2

P

LS

L1

P

LS

VIDEOTAPE/DVDMindJogger Videoquizzes,Chapter 3

VIDEODISCCosmic ChemistryElements, StillPeriodic Table, StillElectrolysis of Water, MovieSodium Chloride, Movie

CD-ROMChemistry: Matter and ChangeSeparating Substances, ExplorationPhysical and Chemical Properties, VideoSeparating Mixtures, ExplorationMetal Alloys, Experiment

The following multimedia for this chapter are available from Glencoe.

Look for the following icons for strategies that emphasize different learning modalities.KinestheticMeeting Individual Needs, pp. 58, 61, 66; Reteach,

p. 59; Check for Understanding, p. 69; Extension, p. 77

Visual-SpatialCheck for Understanding, pp. 58, 65, 76;

Chemistry Journal, pp. 67, 76; Meeting IndividualNeeds, p. 70; Visual Learning, p. 73; Reteach, p. 77

InterpersonalReteach, p. 69; Reinforcement, p. 72

IntrapersonalExtension, pp. 59, 72; Chemistry Journal, p. 71;

Enrichment, p. 74

LinguisticChemistry Journal, pp. 56, 64; Portfolio, p. 57

Key to Teaching Strategies

Glencoe Technology

Multiple Learning Styles

CHAPTER 3 RESOURCE MANAGER

Assessment Planner

Portfolio AssessmentProblem-Solving Lab, TWE p. 60

Assessment, TWE, p. 66ChemLab, TWE, p. 79Portfolio, TWE, p. 81

Performance AssessmentAssessment, TWE, pp. 58, 62Discovery Lab, SE, p. 55MiniLab, SE, p. 68ChemLab, SE, pp. 78–79

Knowledge AssessmentAssessment, TWE, pp. 59, 65Demonstration, TWE, p. 63Section Assessment, SE,pp. 60, 65, 69, 77

Chapter Assessment, SE,pp. 82–85

Skill AssessmentMiniLab, TWE, p. 68Assessment, TWE, pp. 69,73, 77

54 Chapter 3

What You’ll LearnYou will distinguishbetween physical andchemical properties.

You will classify matter bycomposition: element, com-pound, or mixture.

You will identify observablecharacteristics of chemicalreactions.

You will explain the funda-mental law of conservationof mass.

Why It’s ImportantYou are completely sur-rounded by matter. To betterunderstand this matter—howit affects you, how you affectit, and how it can be manipu-lated for the benefit of soci-ety—you need to build a basicunderstanding of the typesand properties of matter.

��

��

Matter—Properties andChanges

CHAPTER 3

Visit the Chemistry Web site atscience.glencoe.com to findlinks about matter.

Chemistry is the study of matterand its properties. Every aspect ofthese divers’ environment, underwater and on land, is some formof matter.

3CHAPTER

Tying to PreviousKnowledgeHave students review the followingconcepts before studying thischapter.Chapter 1: matter, qualitative andquantitative aspects of chemistryChapter 2: significant figures

Using the PhotoAsk students to identify the typesof matter seen in this photograph.Encourage them to be specific intheir descriptions. Solids areevident in the coral reef (mostlycalcium carbonate); the divers’bodies (compounds of carbon,hydrogen, oxygen, nitrogen,phosphorus, calcium, sulfur, andtrace amounts of other metals);the divers’ wet suits made ofmolecules of the hydrocarbonrubber; the metal of the scubatanks. Liquids are most evident inthe solution of salt water. Gasesare evident in the escapingoxygen bubbles.

Chapter ThemesThe following themes from theNational Science EducationStandards are covered in thischapter. Refer to page 4T of theTeacher Guide for an explanationof the correlations.Systems, order, and organization(UCP.1)Evidence, models, and explanation(UCP.2)Form and function (UCP.5)

DISCOVERY LAB

Purpose Students will examine several types ofchemical changes.

Safety and DisposalUse gloves when handling HCl. The HClcan be washed down the sink with a lot ofwater. The unreacted zinc can be reused.ZnCl2 solution can be flushed down thedrain.

Teaching Strategies• If you are using smaller test tubes,

about 3 to 5 mL of 6M HCl will work. • See page 54C for preparation of

solutions.

Expected ResultsThe zinc reacts with hydrochloric acid toproduce zinc chloride (which is solubleand, therefore, not easily seen) andhydrogen gas (seen as bubbles). When a

lighted splint is brought close to themouth of the test tube, the hydrogengas reacts with oxygen in the air toproduce gaseous water. The reactionproduces a pop or “bark.”

AnalysisAnswers will vary. Students might havethought that no reaction would occur. The“bark” is the result of a reaction betweenthe gas that was produced and oxygen.

P

LS

54

http://science.glencoe.com

55

3.1Section

1 Focus

Before presenting the lesson, display Section Focus Transparency 9 on the overhead projector. Havestudents answer the accompanyingquestions using Section FocusTransparency Master 9.

2 Teach

P

ELL

LS

L1

P

LS

Focus Transparency

3.1 Properties of Matter 55

DISCOVERY LAB

Materials

large test tubetest-tube holder or rack10 mL HCl zinc metalwood splintmatch or burner

Observing Chemical Change

Consider the metal objects that are part of the everyday world. Amailbox, for example, stands outside day in and day out, without

seeming to change. Under what conditions does metal exhibit chem-ical change?

Safety Precautions

Procedure

1. Place a piece of zinc metal in a large test tube.

2. Add approximately 10 mL of 3M hydrochloric acid (HCl) to the testtube. Record your observations. CAUTION: HCI causes burns and hazardous fumes.

3. When the zinc and HCl have reacted for approximately 1 min,bring a lighted, glowing wood splint to the mouth of the testtube. CAUTION: Be sure the test tube is facing away from yourface when the splint is brought near. Again record your observations.

Analysis

What may have caused the dynamic reaction you observed in step 3?Did you expect this reaction? Explain.

Always wear eye goggles, gloves, and anapron when experimenting with chemicals.Use caution when handling an open flame.

Objectives• Identify the characteristics

of a substance.

• Distinguish between physi-cal and chemical properties.

• Differentiate among thephysical states of matter.

Vocabularysubstancephysical propertyextensive propertyintensive propertychemical propertystates of mattersolidliquidgasvapor

Section 3.1 Properties of Matter

Imagine yourself scuba diving through a complex biological ecosystem suchas a coral reef. What kinds of things fill your imagination? Regardless of whatyou envision, there is only one answer—you see matter. The diversity of mat-ter in the world and in the universe is astounding. From pepperoni pizzas tosupernovas, it’s all matter. If we are to understand this diversity, we must startwith a way of organizing and describing matter.

SubstancesRecall from Chapter 1 that chemistry is the study of matter, and matter isanything that has mass and takes up space. Everything around you is mat-ter; including things such as air and microbes, which you cannot see. Forexample, table salt is a simple type of matter that you are probably familiarwith. Table salt has a unique and unchanging chemical composition. It isalways 100% sodium chloride and its composition does not change from onesample to another. Matter that has a uniform and unchanging compositionis called a substance, also known as a pure substance. Table salt is a sub-stance. Another example of a pure substance is water. Water is always com-posed of hydrogen and oxygen. Seawater, on the other hand, is not asubstance because samples taken from different locations will probably have

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of th

e M

cGra

w-H

ill C

ompa

nies

, Inc

.

Section Focus Transparency 9 States of MatterUse with Chapter 3, Section 3.1

Chemistry: Matter and Change

Section Focus Transparencies

What matter is shown in all three photographs?What is different about the matter in each photograph?

1

2

Quick Demo

Show students a beaker ofdistilled water and a beaker ofunsaturated salt solution. Askthem if the beakers containpure substances and how theywould confirm their hypoth-esis. A visual inspectionwould lead students tobelieve both were puresubstances. However, somestudents may realize thatfurther tests would be neces-sary to confirm this. Studentsmay suggest evaporation orthe use of a conductivityapparatus to show that thesecond beaker is actually amixture of substances. It is asolution.

P

LS

Resource ManagerResource Manager

Study Guide for Content Mastery,pp. 13–14

Solving Problems: A Chemistry Handbook, Section 3.1

Section Focus Transparency 9 and Master

Lab Manual, pp. 17–20 L2

P

LS

P

ELL

LS

L1

P

LS

L2

P

LS

L2

P

LS

differing compositions. That is, they will contain differing amounts of water,salts, and other dissolved substances. Given this definition, what other puresubstances are you familiar with? Substances are important; much of yourchemistry course will be focused on the processes by which substances arechanged into different substances.

Physical Properties of MatterYou are used to identifying objects by their properties—their characteristicsand behavior. For example, you can easily identify a pencil in your backpackbecause you recognize its shape, color, weight, or some other property. Thesecharacteristics are all physical properties of the pencil. A physical propertyis a characteristic that can be observed or measured without changing the sam-ple’s composition. Physical properties describe pure substances, too. Becausesubstances have uniform and unchanging compositions, they have consistentand unchanging physical properties as well. Density, color, odor, taste, hard-ness, melting point, and boiling point are common physical properties thatscientists record as identifying characteristics of a substance. Sodium chlo-ride forms solid, white crystals at room temperature, all having the sameunique salty taste. Table 3-1 lists several common substances and their phys-ical properties.

Extensive and intensive properties Physical properties can be furtherdescribed as being one of two types. Extensive properties are dependent uponthe amount of substance present. For example, mass, which depends on theamount of substance there is, is an extensive property. Length and volume arealso extensive properties. Density, on the other hand, is an example of an inten-

sive property of matter. Intensive properties are independentof the amount of substance present. For example, density of asubstance (at constant temperature and pressure) is the sameno matter how much substance is present.

A substance can often be identified by its intensive prop-erties. In some cases, a single intensive property is uniqueenough for identification. During the California gold rush,miners relied on gold’s characteristic density (19 g/cm3) toseparate valuable gold-containing flakes from riverbed sand.The process used by the miners is shown in Figure 3-1.Another intensive property of gold is its distinctiveappearance. Unfortunately, miners often learned that iden-tification of gold based on appearance alone was mislead-ing. Figure 3-2 shows a nugget of the relatively worthless

56 Chapter 3 Matter—Properties and Changes

Figure 3-1

Miners relied on the physicalproperty of density to distin-guish gold (19 g/cm3) from theworthless minerals in their sluicepans. The density of pyrite, aworthless mineral often mis-taken for gold, is 5 g/cm3.

Physical Properties of Common Substances

State Melting Boiling DensitySubstance Color at 25°C point (°C) point (°C) (g/cm3)

Oxygen Colorless Gas �218 –183 0.0014

Mercury Silver Liquid –39 357 13.5

Water Colorless Liquid 0 100 1.00

Sucrose White Solid 185 Decomposes 1.59

Sodium White Solid 801 1413 2.17chloride

Table 3-1

Science WriterDo you get excited about newsin science and technology? Doyou like to explain informationin a way that others find inter-esting and understandable?Then consider a career as a science writer.

Science writers keep up-to-dateon what is happening in theworld of science and translatethat news so nonscientists canunderstand it. These writerswork for newspapers, maga-zines, scientific publications,television stations, and Internetnews services. Lots of curiosity,as well as a degree in a scienceand/or journalism, is essential.

56

CHEMISTRY JOURNAL CHEMISTRY JOURNAL

Life on Other PlanetsLinguistic Ask students to write acreative story about noncarbon-

based life on another planet. As theyresearch the elements that make up thelife forms of their planet, they shouldidentify whether the properties arephysical or chemical. If the properties are physical, students should identify themas either extensive or intensive.

P

LS

L2

P

LS

IdentifyingMisconceptions

Students may think that becauseextensive and intensive proper-ties are both physical propertiesthat they both depend on theamount of the substance beinginvestigated. Uncover the MisconceptionReview the definitions of exten-sive and intensive properties.Present the students with a tableor chart from some authoritativesource such as the CRC Hand-book of Chemistry and Physics toreinforce the idea that the conceptof extensive and intensive proper-ties is a valid distinction.Demonstrate the ConceptShow the students two pieces ofthe same type of wood that areobviously different lengths.Measure each piece and explainthat length is an extensive phys-ical property because themeasurements are different forthe different amount of woodpresent. Next place the twopieces of wood in a container ofwater and show how both float.In this case, density is the inten-sive property that is illustrated.Explain how you have proventhat density of the wood is thesame for the long piece as for theshort piece because both piecesfloat the same regardless of theamount of wood in the water. Assess New KnowledgeHave the students research phys-ical properties of some commonsubstances and create a tablelisting some extensive and someintensive properties. Ask thestudents to choose one propertyof a substance they investigatedand explain why that property isextensive or intensive. Have themoffer some demonstration toillustrate the concept.

P

LS CD-ROMChemistry: Matter and ChangeExploration: Separating Substances Video: Physical and ChemicalProperties

Pages 54–571(A), 2(A), 3(D), 4(A), 4(C)

mineral pyrite, often called “fool’s gold,” which looks very similar to actualgold nuggets. Such errors in identification based on the intensive property ofappearance fooled many miners into falsely thinking they had struck it rich!

Chemical Properties of MatterSome properties of a substance are not obvious unless the substance haschanged composition as a result of its contact with other substances or theapplication of thermal or electrical energy. The ability of a substance to com-bine with or change into one or more other substances is called a chemicalproperty. The ability of iron to form rust when combined with air is anexample of a chemical property of iron. Similarly, the inability of a substanceto change into another substance is also a chemical property. For example,when iron is placed in nitrogen gas at room temperature, no chemical changeoccurs. The fact that iron does not undergo a change in the presence of nitro-gen is another chemical property of iron.

Observing Properties of MatterEvery substance has its own unique set of physical and chemical properties.Table 3-2 lists several of these properties of copper. Figure 3-3 shows phys-ical and chemical properties of copper. What physical and chemical proper-ties are evident in these photos?


Figure 3-3

These photos illustrate some ofthe physical and chemical prop-erties of copper as it exists inthe form of hardware andthe Statue of Liberty .b

a

Figure 3-2

Gold and pyrite, or "fool’sgold" , have similar physicalproperties but are different samples of matter.

ba

Properties of Copper

Physical properties Chemical properties

Table 3-2a

b

a bGold Pyrite

• Reddish brown, shiny

• Easily shaped into sheets (malleable) and drawn into wires(ductile)

• Good conductor of heat and electricity

• Density � 8.92 g/cm3

• Melting point � 1085°C

• Boiling point � 2570°C

• Forms green copper carbonate compound when in contact withmoist air

• Forms new substances when com-bined with nitric acid and sulfuricacid

• Forms a deep blue solution whenin contact with ammonia

57

Quick Demo

Show studentssome copper turnings or foiland have them list the observ-able properties of these items.Roll the copper into a ball smallenough to fit into a crucible.Determine the mass of thecrucible with the copper in it.Next, heat the copper stronglyfor 5 to 10 minutes and havestudents make observationsagain. Ask them to predict whathas happened to the mass, then weigh the copper oxideproduct. (When finished, CuOcan be thrown away.) Askstudents to distinguish betweenphysical and chemical propertiesthat they have witnessed.

P

LS

PortfolioPortfolio

Linguistic Have students use the CRCHandbook of Chemistry and Physics to

research the physical and chemical proper-ties of a particular element or compound.Next, have them write a summary relating

how that particular property is useful for aproduct made with that element or com-pound. For example, copper’s malleability,conductivity, and high melting point mightmake it ideal for cookware.

P

LS

PP

LS

L2

P

LS

Properties and Uses

Career Path A careeras a science writer wouldinclude high schoolcourses in Earth science,math, chemistry, biology,

and physics. College course workshould build on the science founda-tion and also include technicalwriting and journalism.Career Issue Have the studentsread science articles on varioustopics and in a variety of main-stream publications. Ask them toevaluate the effectiveness of thewriting. How well did the writerclarify or explain a scientificconcept or development?

For More Information For more information about careersin science writing, students cancontact the

National Association for Science Writers, Inc.

P.O. Box 294Greenlawn, NY 11740www.nasw.org

In-Text QuestionPage 57 What physical and chem-ical properties are evident in thesephotos? Physical: color, luster,hardness, malleability, ductility,physical state Chemical: formation of greencopper carbonate

CAREERS USING CHEMISTRY

Observations of properties may vary depending on the conditions of theimmediate environment. It is important to state the specific conditions inwhich observations are made because both chemical and physical propertiesdepend on temperature and pressure. Consider the properties of water, forexample. You may think of water as a liquid (physical property) that is notparticularly chemically reactive (chemical property). You may also know thatwater has a density of 1.00 g/cm3 (physical property). These properties, how-ever, apply only to water at standard “room” temperature and pressure. At tem-peratures greater than 100°C, water is a gas (physical property) with a densityof about 0.0006 g/cm3 (physical property) that reacts rapidly with many dif-ferent substances (chemical property). As you can see, the properties of waterare dramatically different under different conditions.

States of MatterImagine you are sitting on a bench, breathing heavily and drinking water aftera tiring game of soccer. In this scenario, you are in contact with three differentforms of matter; the bench is a solid, the water is a liquid, and the air you breatheis a gas. In fact, all matter that exists on Earth can be classified as one of thesephysical forms called states of matter. Scientists recognize a fourth state ofmatter called plasma, but it does not occur naturally on Earth except in the formof lightning bolts. The physical state of a substance is a physical property ofthat substance. Each of the three common states of matter can be distinguishedby the way it fills a container.

Solids A solid is a form of matter that has its own definite shape and vol-ume. Wood, iron, paper, and sugar are examples of solids. The particles ofmatter in a solid are very tightly packed; when heated, a solid expands, butonly slightly. Because its shape is definite, a solid may not conform to theshape of the container in which it is placed. The tight packing of particles ina solid makes it incompressible; that is, it cannot be pressed into a smallervolume. It is important to understand that a solid is not defined by its rigid-ity or hardness; the marble statue in Figure 3-4 is rigid whereas wax sculp-ture is soft, yet both are solids.

Liquids A liquid is a form of matter that flows, has constant volume, andtakes the shape of its container. Common examples of liquids include water,blood, and mercury. The particles in a liquid are not rigidly held in placeand are less closely packed than are the particles in a solid: liquid particles


Figure 3-4

The properties of the solidmaterials marble and wax make these sculptures possible.Particles in a solid are tightlypacked , giving definite shapeand volume to the solid.

c

ba

Solid

a b

c

Go to the Chemistry InteractiveCD-ROM to find additionalresources for this chapter.

58

Performance Givestudents a large (3 to 4 cm diam-eter) cork and ask them to designan experiment to determine itsdensity. Next, have them run thecork through a cork press (or avice) and ask them to reassessdensity. Ask them to explain theresults of their experiment in termsof the packing arrangement of theatoms. Students will see thatpressing the cells togetherincreases the number of atomsper unit volume; hence, thedensity increases. Use thePerformance Task Assessment Listfor Designing an Experiment inPASC, p. 23.

3 AssessCheck for Understanding

Visual-Spatial Fill a 50 mL graduatedcylinder with 25 mL of water. Fillanother graduated cylinder with 25 mL of alcohol (methyl, ethyl, orisopropyl may be used). Ask thestudents to predict what will occurwhen the alcohol is poured into the50 mL cylinder containing the waterand mixed. Students will typicallythink the volumes will add to a full 50 mL of alcohol–watermixture; however, the volume isnot additive. Molecules of alcoholslip in between the molecules ofwater. Reinforce this by filling abeaker to the top with marblesand asking students if more mate-rial can be added. Then add sandor water to demonstrate. Todispose of alcohols, evaporateunder a hood.

P

LS

AssessmentAssessment

MEETING INDIVIDUAL NEEDS MEETING INDIVIDUAL NEEDS

Learning DisabledKinesthetic Pass out three plasticpetri dishes and a collection of mar-

bles or large gauge metal shot. Have thestudents arrange the marbles or shot inthe dishes to show the relative packingarrangement of solids, liquids, and gases.These can also be displayed on the over-head projector to show atomic motion inthe three states of matter.

P

LSP

ELL

LS

L1

P

LS


Teaching Transparency 7 and Master

Small-Scale Laboratory Manual, pp. 5–8 L2

P

LS

P

ELL

LS

L2

P

LS

Pages 58–594(A), 4(B), 5(A)


Figure 3-5

Despite having differentshapes, each of these measuringcups holds the same volume ofliquid.

River water flows to fitwithin the boundaries of itsbanks, regardless of the curvesalong its path.

Molecules in a liquid areclosely packed but can still moverelatively freely.

c

b

a

Liquid

a bc

Figure 3-6

Molecules in a gas are farapart and freely moving.

Neon gas completely fills the tubes of the electricartwork.

b

a

are able to move past each other. This allows a liquid to flow and take theshape of its container, although it may not completely fill the container. Aliquid’s volume is constant: regardless of the size and shape of the containerin which the liquid is held, the volume of the liquid remains the same. Thisis why measuring cups used in cooking, such as those pictured in Figure3-5, can be made in a variety of shapes yet still measure the same volume.Because of the way the particles of a liquid are packed, liquids are virtu-ally incompressible. Like solids, liquids tend to expand when heated.

Gases A gas is a form of matter that flows to conform to the shape of itscontainer and fills the entire volume of its container. Examples of gasesinclude neon, which is used in the lighted artwork in Figure 3-6; methane,which is used in cooking; and air, which is a mixture of gases. Compared tosolids and liquids, the particles of gases are very far apart. Because of the sig-nificant amount of space between particles, gases are easily compressed. Theproblem-solving LAB in this section poses several important questions aboutthe practical use of compressed gas.

It is likely that you are familiar with the word vapor as it relates to theword gas. The words gas and vapor, while similar, do not mean the samething and should not be used interchangeably. The word gas refers to a sub-stance that is naturally in thegaseous state at room temperature.The word vapor refers to thegaseous state of a substance that isa solid or a liquid at room tempera-ture. For example, steam is a vaporbecause at room temperature waterexists as a liquid.

bGasa

59

ReteachKinesthetic Have studentsact out the packing of the

different states of matter by“becoming” atoms themselves.Isolate a particular area of theclassroom as the stage so thatstudents can visualize the relativepacking of atoms in the differentstates.

ExtensionIntrapersonal Have studentssearch the Internet for exam-

ples of new materials being devel-oped by various chemicalmanufacturers (DuPont, Dow,Kodak, for instance). Ask studentsto relate the properties of the newmaterials to the arrangement of theatoms or molecules as solids,liquids, or gases.

Knowledge Ask studentsto decide whether the followingstatements are true or false, and to support their choice with textreferences.• A vapor and a gas are the same

thing. F• A liquid conforms to its

container. T• Particles of a gas are spaced

closer together than particles of aliquid. F

• A solid has definite shape butchangeable volume. F


P

ELL

LS

L1

P

LS

Internet Address Book

Note Internet addresses that you find useful in thespace below for quick reference.


Section 3.1 Assessment

1. Describe the characteristics that identify a sampleof matter as being a substance.

2. Classify each of the following as a physical orchemical property.

a. Iron and oxygen form rust.b. Iron is more dense than aluminum.c. Magnesium burns brightly when ignited.d. Oil and water do not mix.e. Mercury melts at �39°C.

3. Create a table that describes the three commonstates of matter in terms of their shape, volume, and compressibility.

4. Thinking Critically Using what you know aboutthe compressibility of gases, explain why the oxy-gen in a SCUBA tank is compressed.

5. Interpreting Data Bromine is a reddish-brownliquid that boils at 59°C. Bromine is highly reactivewith many metals. For example, it reacts withsodium to form a white solid. Classify each of theseproperties of bromine as either a physical or achemical property.

problem-solving LAB

How is compressed gasreleased?Recognizing Cause and Effect Tanks of com-pressed gases are a common sight in a chemistrylaboratory. For example, nitrogen is often flowedover a reaction in progress to displace othergases that might interfere with the experiment.Given what you know about the properties ofgases, explain how compressed nitrogen isreleased.

AnalysisBy definition, the particles of gases are far apartand gases tend to fill their container, even if thecontainer is a laboratory room. Tanks of com-pressed gas come from the supplier capped toprevent the gas from escaping. In the lab achemist or technician attaches a regulator to thetank and secures the tank to a stable fixture.

Thinking Critically1. Explain why the flow of compressed gas must

be controlled for practical use.

2. Predict what would happen if the valve on afull tank of compressed gas were suddenlyopened all the way or if the full tank werepunctured.

The fact that substances can change form, as in the example of waterchanging to steam, is another important concept in chemistry. If you reviewwhat you just learned about physical properties of substances, you can seethat because the particular form of a substance is a physical property, chang-ing the form introduces or adds another physical property to its list of char-acteristics. In fact, resources that provide tables of physical and chemicalproperties of substances, such as the CRC Handbook of Chemistry and Physics,generally include the physical properties of substances in all of the states inwhich they can exist.

Purpose Students will deduce the methodby which the flow of gas out of acompressed tank is controlled.

Process SkillsInferring, predicting, thinking criti-cally, recognizing cause and effect

Teaching Strategies• Identify several real-world situa-

tions (outside a laboratory) wherecompressed gases are used.

• Identify control and safetyfeatures in these situations.

Thinking Critically1. Some kind of valve must be

attached that can limit the exitorifice, thereby limiting theamount of gas that is released.

2. Without the regulator device,the gas would rush out of thetank with a force powerfulenough to transform it into adangerous, uncontrolledprojectile.

Portfolio Have studentsresearch the breathing apparatusthat a scuba diver uses andcompare that equipment withcompressed gas equipment in alaboratory. Reports can be placedin students’ portfolios. PP

LS

L2

P

LS


P

LS

problem-solving LAB

Section Assessment3.1

1. The sample of matter must have auniform and unchanging composi-tion to be a substance.

2. a. chemical d. physicalb. physical e. physicalc. chemical

3. Table should list solid (definitevolume, definite shape, incompress-ible); liquid (definite volume, fillscontainer shape, virtually incom-pressible); gas (fills volume ofcontainer, takes shape of container,compressible).

4. Particles in a gas are spaced farapart and are easily compressed.Therefore, it is possible to put asignificant volume of oxygen in atank, which allows the diver toremain under water longer.

5. color, physical; boiling point, phys-ical; reactive with metals, chemical

60

Pages 60–612(D), 4(A), 4(B), 5(A)

Focus Transparency

61

3.2Section

3.2 Changes in Matter 61

Objectives• Define physical change and

list several common physicalchanges.

• Define chemical change andlist several indications that achemical change has takenplace.

• Apply the law of conserva-tion of mass to chemicalreactions.

Vocabularyphysical changechemical changelaw of conservation of mass

Section Changes in Matter

You learned in Section 3.1 that scientists can describe matter in terms of phys-ical and chemical properties. For example, a physical property of copperallows it to be drawn into copper wire, and a chemical property of copperaccounts for the fact that when a solution of copper ions is combined withammonia, the copper solution changes to a deep blue color. The key conceptin both of these examples is that the substance copper changed in some way.In this section, you’ll explore how matter changes as a result of its physicaland chemical properties.

Physical ChangesA substance often undergoes changes that result in a dramatically differentappearance yet leave the composition of the substance unchanged. An exam-ple is the crumpling of a sheet of aluminum foil. While the foil goes from asmooth, flat, mirrorlike sheet to a round, compact ball, the actual composi-tion of the foil is unchanged—it is still aluminum. Changes such as this, whichalter a substance without changing its composition, are known as physicalchanges. Cutting a sheet of paper and breaking a crystal are other examplesof physical changes in matter. Can you name some other physical changes?Your list might include verbs such as bend, grind, crumple, split, and crush,all of which indicate physical change.

As with other physical properties, the state of matter depends on the tem-perature and pressure of the surroundings. As temperature and pressurechange, most substances undergo a change from one state (or phase) toanother. For example, at atmospheric pressure and at temperatures below0°C, water is in its solid state, which is known as ice. As heat is added to theice, it melts and becomes liquid water. This change of state is a physicalchange because even though ice and water have very different appearances,their composition is the same. If the temperature of the water increases to100°C, the water begins to boil and liquid water is converted to steam. Meltingand formation of a gas are both physical changes and phase changes. Figure3-7 shows condensation, another common phase change. When you encounterterms such as boil, freeze, condense, vaporize, or melt in your study of chem-istry, the meaning generally refers to a phase change in matter.

3.2

a

Figure 3-7

Condensation on an icy bev-erage glass is the result of thephase change of water in a gaseous state to water in a liquid state.

The characteristic “fog” ofdry ice is actually fine waterdroplets formed by condensa-tion of water vapor from the airsurrounding the very cold dryice. Refer to Table C-1 inAppendix C for a key to atomcolor conventions.

b

a

c

b

a b

1 Focus


2 Teach

P

ELL

LS

L1

P

LS

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of th

e M

cGra

w-H

ill C

ompa

nies

, Inc

.



Section Focus Transparency 10Physical and ChemicalChanges

Use with Chapter 3, Section 3.2

How is the tree changed by each action shown?Which action do you think shows a more complete change?

1

2

Quick Demo

CAUTION:Perform this demo under ahood. Place several moth ballsin a beaker. Place a flask halffilled with cold water on top toserve as a condensing “lid.”Heat the moth balls until theyhave melted and ask studentsto observe and diagram thechanges. Remove the heatsource and ask students toagain observe the changes.With heat, students will seethe change from solid toliquid, solid to vapor, andliquid to vapor. On cooling,students will see liquid tosolid and vapor to solid, orvapor to a liquid.

P

LS


GiftedKinesthetic Have gifted stu-dents identify an unknown

from a list of possibilities based on the melting point and boiling point.Students should plot a heating/coolinggraph of time on the x-axis versus temper-ature on the y-axis.

P

LS

L3

P

LS


Study Guide for Content Mastery,p.15

Challenge Problems, p. 3Solving Problems: A Chemistry Handbook, Section 3.2


P

ELL

LS

L1

P

LS

L2

P

LS

L3

P

LS

L2

P

LS

The temperature and pressure at which a substance undergoes a phasechange are important physical properties. These properties are listed as themelting and boiling points of the substance. Table 3-1 on page 56 providesthis information for several common substances. Like density, the meltingpoint and boiling point are intensive physical properties that may be used toidentify unknown substances. For example, if an unknown solid melts at801°C and boils at 1413°C—very high temperatures—it is most probablysodium chloride, or common table salt. Tables of intensive properties, suchas those given in the CRC Handbook of Chemistry and Physics, are indis-pensable tools in identifying unknown substances from experimental data.

Chemical ChangesAs you learned earlier, chemical properties relate to the ability of a substanceto combine with or change into one or more substances. A process thatinvolves one or more substances changing into new substances is called achemical change, which is commonly referred to as a chemical reaction. Thenew substances formed in the reaction have different compositions and dif-ferent properties from the substances present before the reaction occurred. Forexample, the crushing of grapes that is part of the wine-making process is aphysical change, but the fermentation of the juice, sugars, and other ingredi-ents to wine is a chemical change. The Chemistry and Society feature at theend of the chapter describes some interesting consequences of physical andchemical changes in the production of concrete.

Let’s consider again the rusting of iron. When a freshly exposed iron surface is left in contact with air, it slowly changes into a new substance,namely, the rust shown in Figure 3-8a. The iron reacts with oxygen in the airto form a new substance, rust. Rust is a chemical combination of iron and oxy-gen. In chemical reactions, the starting substances are called reactants and thenew substances that are formed are called products. Thus iron and oxygen arereactants and rust is a product. When you encounter terms such as explode,rust, oxidize, corrode, tarnish, ferment, burn, or rot, the meaning generallyrefers to a chemical reaction in which reactant substances produce differentproduct substances.


a

Figure 3-8

The formation of a gas orsolid when reactants mix oftenindicates that a chemical reac-tion has taken place. Rust is theresult of a chemical reaction.

Color changes generallyindicate that a chemical reactionhas taken place. One example isthe color change of tree leavesin the fall.

b

a

b

Performance The reac-tion of iron with oxygen costsAmerican industry a great deal ofmoney. Have the students choose aparticular industry (such as agricul-ture, transportation, or construction)and give an oral report on how theindustry deals with the problem of rust. Use the Performance Task Assessment List for OralPresentation in PASC, p. 71.


Quick Demo

Pour 20 to 25 mL of ethanolinto an empty water cooler jugor plastic gallon milk bottle. Rollthe ethanol around to coat theinside of the bottle and pouroff the excess. Turn off the class-room lights and, with a lightedsplint that is taped to a meterstick, ignite the top of thebottle. CAUTION: Perform frombehind an explosion shield andkeep your hand clear of thebottle opening. After the explo-sion, show the water that formsin the reaction by pouring itinto a beaker. Students willfrequently clamor for an encoreperformance, which is mostoften unsuccessful because ofthe presence of the otherproduct of the reaction, carbondioxide. Have the students iden-tify the reactants (ethanol andoxygen) and the products(water and carbon dioxide).The carbon dioxide can beflushed out of the bottle bywater displacement.

P

LS

Atoms in Motion

Purpose To observe atomic motion and the forma-tion of an alloy, brass

MaterialsNew pennies (3); zinc (2 g); NaOH

(5 g); porcelain evaporating dish; forceps;paper towels; hot plate

Safety Precautions

Disposal Decant the cooled NaOH solu-tion from the solid zinc. Neutralize theNaOH and rinse down the drain. Dry thezinc in an evaporating dish and reuse. Donot allow the zinc plating solution to comein contact with flammable materials.

ProcedureDissolve 5 g NaOH in 25 mL of water in anevaporating dish. CAUTION: NaOHcauses severe burns; avoid skin contact.Rinse spills with plenty of water. Weargoggles and apron. Add a 2 g piece of zinc to the NaOH solution. Place the solution on the hot plate and heat to just below the boiling point. Keep one penny as acontrol. Immerse two new pennies in theNaOH–zinc plating bath. After one minute,

P

LS

Demonstration

62

EnrichmentThe first true chemist is consideredby many to be Robert Boyle(1627–1691), known for his workon the relationship between gaspressure and volume.

The German chemist GeorgStahl (1660–1734) was also inter-ested in the chemistry and physicsof gases, in particular, combustion.He believed that when a substanceburned, “phlogiston” flowed out ofthe material.

The English scientist and cler-gyman Joseph Priestley(1773–1804) is credited with thediscovery of the active role ofoxygen in combustion. He calledoxygen “dephlogisticated air.”

Antoine Lavoisier, with care-fully recorded measurements,showed that mass was conserved incombustion reactions involvingoxygen. It was Lavoisier whonamed the gas that supportscombustion “oxygene,” meaning“generator of acid” (it was origi-nally believed to be an importantpart of all acids).

Have students research andreport on one of these earlypioneers. L2

P

LS

use forceps to turn the pennies over. Keepthe pennies immersed until they are silverin color. Using forceps, remove the twocoins from the hot bath, rinse with coldwater, and pat dry with paper towels.Remove the evaporating dish from the hotplate. Place one of the plated pennies on thehot surface. In a few seconds, the platedcoin will return to its original copper color.After a few more seconds, the color of thecoin will appear golden. Remove the coin

from the hot plate and allow it to cool.CAUTION: Do not touch the hot penny.Display the three pennies to the class.

ResultsThe control penny remains coppercolored. The zinc-plated penny is silvercolored. The third penny is gold colored.

AnalysisDescribe the alloy brass. Brass is a solid

solution of the metallic elements copperand zinc.

Knowledge Ask students whyheat is needed to cause the zinc coating todiffuse into the copper. Heat increases themotion of the atoms and separates andexpands the layers of atoms, thusallowing them to migrate more easily.


63

CHEMLAB

Evidence of a chemical reaction As Figure 3-8a shows, rust is a brown-ish-orange powdery substance that looks very different from iron and oxygen.Rust is not attracted to a magnet, whereas iron is. The observation that the prod-uct (rust) has different properties than the reactants (iron and oxygen) is evi-dence that a chemical reaction has taken place. A chemical reaction alwaysproduces a change in properties. Figures 3-8 and 3-9 illustrate several com-mon indicators of chemical change. The CHEMLAB at the end of the chap-ter provides a practical laboratory experience with chemical reactions.

Conservation of MassAlthough chemical reactions have been observed over the course of humanhistory, it was only in the late eighteenth century that scientists began to usequantitative tools to monitor chemical changes. The revolutionary quantita-tive tool developed at this time was the analytical balance, which was capa-ble of measuring very small changes in mass.

By carefully measuring mass before and after many chemical reactions, itwas observed that, although chemical changes occurred, the total massinvolved in the reaction remained constant. The constancy of mass in chem-ical reactions was observed so often that scientists assumed the phenomenonmust be true for all reactions. They summarized this observation in a scien-tific law. The law of conservation of mass states that mass is neither creatednor destroyed during a chemical reaction—it is conserved. This law was oneof the great achievements of eighteenth-century science. The equation formof the law of conservation of mass is

Massreactants � Massproducts

The French scientist Antoine Lavoisier (1743–1794) was one of the firstto use an analytical balance like the one shown in Figure 3-10 to monitorchemical reactions. He studied the thermal decomposition of mercury(II)oxide, known then as calx of mercury. Mercury(II) oxide is a powderyred solid. When it is heated, the red solid reacts to form silvery liquidmercury and colorless oxygen gas as shown in Figure 3-11 on the nextpage. The color change and production of a gas are indicators of a


Figure 3-9

Energy changes indicatechemical reactions. For example,the burning of wood is a com-mon example of a reaction thatreleases heat.

The change in the smell of asubstance or the production ofan odor may be an indication ofa chemical reaction.

b

a

a b

Figure 3-10

The development of scientifictools such as this analytical bal-ance gave a degree of precisionto measurements that greatlyimproved general scientificunderstanding.


ChemLab 3, located at the end ofthe chapter, can be used at thispoint in the lesson.


Math Skills Transparency 2 and Master

P

ELL

LS

L2

P

LS

P

ELL

LS

L2

P

LS


chemical reaction. When the reaction is performed in a closed container, theoxygen gas cannot escape and the mass before and after the reaction can bemeasured. The masses will be the same.

Mercury(II) oxide yields mercury � oxygen

�

A more modern digital analytical balance can be used to prove the conser-vation of mass of this example. The law of conservation of mass is one of themost fundamental concepts of chemistry. Let’s examine more closely somesituations that illustrate the concept. Example Problem 3-1 leads you througha sample calculation. The practice problems also illustrate the law of con-servation of mass.

200 g � 16 g��mass of products

216 g��Mass of reactant

EXAMPLE PROBLEM 3-1

Mercury occurs naturally in air,water, soil, and living organisms.Seafood that is intended forhuman consumption is monitoredto ensure that the products donot contain levels of mercuryexceeding the established limitsfor public safety.

Figure 3-11

Lavoisier’s experimental decom-position of mercury(II) oxide isone proof of the law of conser-vation of mass. Although achemical reaction is obvious(powder to liquid mercury), mat-ter was neither created nordestroyed.

Conservation of MassIn an experiment, 10.00 g of red mercury(II) oxide powder is placedin an open flask and heated until it is converted to liquid mercuryand oxygen gas. The liquid mercury has a mass of 9.26 g. What isthe mass of oxygen formed in the reaction?

1. Analyze the ProblemYou are given the mass of a reactant and the mass of one of theproducts in a chemical reaction. Applying the law of conserva-tion of mass, the total mass of the products must equal the totalmass of the reactants. This means that the mass of the liquidmercury plus the mass of the oxygen gas must equal the mass ofthe mercury(II) oxide powder.

Known Unknown

Mass of mercury(II) oxide � Mass of oxygen formed �10.00 g ? gMass of liquid mercury � 9.26 g

64

Quick Demo

Place 3.5 g of sulfur powderand 6.0 g of iron filings in sepa-rate weighing dishes. Havestudents record the physicalproperties of each substance.Hold a magnet underneath thedish of iron filings to demon-strate magnetic properties.Combine the two dishes andstir with a glass rod, then pourinto a test tube. Heat the testtube strongly. CAUTION: Weargoggles and perform in fumehood! Once the reaction iscomplete, plunge the test tubeinto a beaker of cold water.The test tube will crack andyou will be able to retrieve theiron sulfide product usingforceps. Show that the physicalproperties have changed andweigh the isolated iron sulfidechunks. The iron sulfide is agray, nonmagnetic solid; themass should be close to 9.5 g.P

LSPROBLEMS

Have students refer to AppendixD for complete solutions toPractice Problems.6. 89.4 g7. 24.1 g of chlorine gas is

used in the reaction.Because the sodium reactswith excess chlorine, all ofthe sodium (15.6 g) is usedin the reaction.

8. 91.5 g of bromine reactedand 101.8 g of aluminumbromide were formed.

9. 6.6 g


The Conservation of EnergyLinguistic The law of conservation ofmatter, formalized by Lavoisier, was a

major achievement for the eighteenthcentury. However, it is really an incompletestatement without considering it with the

law of conservation of energy. Have studentsresearch and write a short report on theexperiments of the twentieth century thatled to the formulation of the law of conser-vation of energy.

P

LS

L2

P

LS

Pages 62–652(C), 5(A), 5(C)


Laboratory Manual, pp. 21–24 L2

P

LS


PRACTICE PROBLEMS6. From a laboratory process designed to separate water into hydrogen

and oxygen gas, a student collected 10.0 g of hydrogen and 79.4 g ofoxygen. How much water was originally involved in the process?

7. A student carefully placed 15.6 g of sodium in a reactor supplied withan excess quantity of chlorine gas. When the reaction was complete,the student obtained 39.7 g of sodium chloride. How many grams ofchlorine gas reacted? How many grams of sodium reacted?

8. In a flask, 10.3 g of aluminum reacted with 100.0 g of liquid bromineto form aluminum bromide. After the reaction, no aluminumremained, and 8.5 grams of bromine remained unreacted. How manygrams of bromine reacted? How many grams of compound wereformed?

9. A 10.0-g sample of magnesium reacts with oxygen to form 16.6 g ofmagnesium oxide. How many grams of oxygen reacted?


10. Describe the results of a physical change and listthree examples of physical change.

11. Describe the results of a chemical change. Listfour indicators of chemical change.

12. Solve each of the following.

a. In the complete reaction of 22.99 g of sodiumwith 35.45 g of chlorine, what mass of sodiumchloride is formed?

b. A 12.2-g sample of X reacts with a sample ofY to form 78.9 g of XY. What is the mass of Ythat reacted?

13. Thinking Critically A friend tells you, “Becausecomposition does not change during a physicalchange, the appearance of a substance does notchange.” Is your friend correct? Explain why.

14. Classifying Classify each of the following ex-amples as a physical change or a chemical change.

a. crushing an aluminum canb. recycling used aluminum cans to make new

aluminum cansc. aluminum combining with oxygen to form alu-

minum oxide

For more practice withconservation of mass,go to SupplementalPractice Problems in

Appendix A.

Practice!

2. Solve for the UnknownWrite an equation showing conservation of mass of reactants andproducts.

Massreactants � Massproducts

Massmercury(II) oxide � Massmercury � Massoxygen

Solve the equation for Massoxygen.

Massoxygen � Massmercury(II) oxide � Massmercury

Substitute known values and solve.

Massoxygen � 10.00 g � 9.26 g

Massoxygen � 0.74 g

3. Evaluate the AnswerThe sum of the masses of the two products equals the mass of thereactant, verifying that mass has been conserved. The answer is cor-rectly expressed to the hundredths place.

65


Visual-SpatialSet up simultaneous experi-

ments. In one small beaker, place a scoop of baking soda (sodiumhydrogen carbonate) and add 10 mL of vinegar (acetic acid).Invert another larger beaker overthe top to capture the carbondioxide–water that is produced. Inthe second experiment, pour severalmL of carbonated beverage (clubsoda) into a small beaker and placeon a hotplate. Again, invert a largerbeaker over the top of the smallerbeaker to capture the carbondioxide–water that is produced.When both reactions are complete,slide a glass plate under eachinverted beaker and test for thepresence of carbon dioxide byextinguishing a splint or candle.Ask the students how the firstexperiment is different from thesecond. The first experimentgenerates carbon dioxide througha chemical change, the secondthrough a physical change.

Reteach Set up a beaker of water andanother beaker of ethanol. Placeseveral ice cubes in each beaker.Ask students to relate their obser-vations to the physical states of thematter involved. The ice will floaton the water because the solid isless dense than the liquid;however, ice is more dense thanliquid ethanol and will sink. Todispose of ethanol, evaporateunder a hood.

Knowledge Set out a trayof objects (glassware, files, clamps,splints). Have the students team upand choose three objects from thetray and list the physical propertiesof each object and some physicalchanges that the object couldundergo. Repeat for chemical prop-erties and changes.

P

COOP LEARN

LS

P

ELL

LS

L2

P

LS



10. During a physical change, a substanceis altered but its composition does notchange. Examples will vary but mayinclude changes such as melting,freezing, boiling, bending, and tearing.

11. During a chemical change, the compo-sition of a substance is altered.Possible indicators of chemical changeinclude a change in color, odor, or

temperature, and the formation of agas or solid from a liquid.

12. a. 58.44 g of sodium chlorideb. 66.7 g of Y

13. The statement is false. While thecomposition does not change, achange in appearance often accompanies a physical change.

14. a. physical; b. physical; c. chemical

66

3.3Section

1 Focus

Before presenting the lesson, displaySection Focus Transparency 11 on the overhead projector. Havestudents answer the accompanyingquestions using Section FocusTransparency Master 11.

2 Teach

Portfolio Have thestudents look around the room and generate a list of items that are mixtures and items that aresubstances. Have them identify thecriteria they are using for classifi-cation and rough percentages ofeach item in each category. Listscan be placed in their portfolios.Answers will vary but there areusually higher percentages ofmaterials that are classified asmixtures. PP

LS

L2

P

LS


P

ELL

LS

L1

P

LS


Section 3.3 Mixtures of Matter

Objectives• Contrast mixtures and

substances.

• Classify mixtures as homo-geneous or heterogeneous.

• List and describe severaltechniques used to separatemixtures.

Vocabularymixtureheterogeneous mixturehomogeneous mixturesolutionfiltrationdistillationcrystallizationchromatography

When scientists speak of the composition of matter, they are referring to thekinds and amounts of components of which the matter is made. On the basisof composition alone, all matter can be classified into two broad categories:substances or mixtures. You have already learned that a pure substance is aform of matter with a uniform and unchanging composition. You also knowthat the intensive properties of pure substances do not change, regardless ofthe physical state or amount of the substance. But what is the result when twoor more substances are combined?

MixturesA mixture is a combination of two or more pure substances in which eachpure substance retains its individual chemical properties. The composition ofmixtures is variable, and the number of mixtures that can be created by com-bining substances is infinite. Although much of the focus of chemistry is thebehavior of substances, it is important to remember that most everyday mat-ter occurs as mixtures. Substances tend naturally to mix; it is difficult to keepthings pure.

Two mixtures, sand and water, and table salt and water, are shown inFigure 3-12a. You know water to be a colorless liquid. Sand is a grainy solidthat does not dissolve in water. When sand and water are mixed, the twosubstances are in contact, yet each substance retains its properties. Thesand and water have not reacted. Just by looking at the sand–water mixturein beaker A, it is easy to see each separate substance. Some mixtures, how-ever, may not look like mixtures at all. The mixture of table salt and waterin the beaker labeled B is colorless and appears the same as pure water. Howcan you determine if it is a mixture? If you were to boil away the water,you would see a white residue. That residue, shown in Figure 13-12b, isthe salt. Thus, the colorless mixture actually contained two separate sub-stances. The salt and the water physically mixed but did not react and wereseparated by the physical method of boiling.

Figure 3-12

The components of the sandand water mixture (left) areobvious, whereas the compo-nents of the table salt and watermixture (right) are not.

The salt component becomesobvious when the mixture isboiled.

b

a

a b

Pages 66–674(C)

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of th

e M

cGra

w-H

ill C

ompa

nies

,Inc

.

Section Focus Transparency 11 MixturesUse with Chapter 3, Section 3.3



How is the liquid in photograph B made?

What does it have in common with the substance in

photograph A? Photograph C?1

2

A

B

C

Focus Transparency


Visually ImpairedKinesthetic Set up stations withexamples of heterogeneous and

homogeneous mixtures that can bediscerned by touch. Partner visuallyimpaired students with sighted studentsand have them rotate through the stationsto classify each type of mixture. P

LS P

ELL

LS

L1

P

LS


Study Guide for Content Mastery, p.16



P

ELL

LS

L1

P

LS

L2

P

LS

L2

P

LS

Types of mixtures The combinations of pure substances shown inFigure 3-12 are indeed both mixtures, despite their obvious visual differences.Can you think of some way to further define mixtures? Mixtures themselvesare classified as either heterogeneous or homogeneous. A heterogeneousmixture is one that does not blend smoothly throughout and in which the indi-vidual substances remain distinct. The sand and water mixture is an exampleof a heterogeneous mixture. Suppose you draw a drop from the top of the mix-ture using an eyedropper. The drop would be almost completely water. If youdraw a second drop from the bottom of the mixture, that drop would containmostly sand. Thus the composition of the sand–water mixture is not uniform—the substances have not blended smoothly and the two substances of the mix-ture (sand on the bottom and water on the top) remain distinct. In anotherexample, fresh-squeezed orange juice is a mixture of juice and pulp. The pulpcomponent floats on top of the juice component. Is your favorite pizza a mix-ture? The answer is yes when you consider that the pizza is a combination ofdistinct areas of dough, sauce, cheese, and toppings. We can therefore say thatthe existence of two or more distinct areas indicates a heterogeneous mixture.

A homogeneous mixture has constant composition throughout; it alwayshas a single phase. Let’s examine the salt–water mixture using the eyedrop-per. A drop of the mixture from the top of the beaker has the same composi-tion as a drop from the bottom of the beaker. In fact, every drop of the mixturecontains the same relative amounts of salt and water.

Homogeneous mixtures are also referred to as solutions. You are proba-bly most familiar with solutions in a liquid form, such as cough suppressantmedicine and lemonade, but solutions may contain solids, liquids, or gases.Table 3-3 lists the various types of solution systems and gives an example ofeach. Solutions are very important in chemistry, and, in fact, this textbookdevotes an entire chapter to the study of solutions.

The solid–solid solution known as steel is called an alloy. An alloy is ahomogeneous mixture of metals, or a mixture of a metal and a nonmetal inwhich the metal substance is the major component. The U.S. Mint’s goldendollar coin, shown in Figure 3-13, uses a metal alloy composed of 77% cop-per, 12% zinc, 7% manganese, and 4% nickel surrounding a copper core.Alloys are also used in spacecraft and automobiles. What might be the ben-efit of using alloys for these applications? Manufacturers combine the prop-erties of various metals in an alloy to achieve greater strength and durabilityof their products.

3.3 Mixtures of Matter 67

Types of Solution Systems

System Example

Gas–gas Air is primarily a mixture of nitrogen, oxygen, and argongases.

Gas–liquid Carbonated beverages contain carbon dioxide gas in solution.

Liquid–gas Moist air contains water droplets in air (which is a mixture ofgases).

Liquid–liquid Vinegar contains acetic acid in water.

Solid–liquid Sweetened powder drink contains sugar and other solid ingredients in water.

Solid–solid Steel is an alloy of iron containing carbon.

Table 3-3

Figure 3-13

Coins issued by the U.S. Mint are metal alloys. The combina-tion of multiple metals gives thecoins specific properties such ascolor, weight, and durability.

Applying Chemistry Silver mining does notyield pure silver metal. Infact, the highest percentageof silver is found mixed inlead ores, frequently called

lead bullion. The silver is removedby adding small amounts of zinc tothe molten bullion; the zinc alloyswith the silver and floats to thesurface where it is skimmed off,leaving the lead.

In areas where silver miningwas once a major activity, housingdevelopments and other publiccommunities now sit on old minesites. In the mid 1980s, theEnvironmental Protection Agencyconsidered an effort to clean upsome former silver mine sites.However, it was determined thatresidents were not experiencing ahigher health risk and “stirring up”the areas could cause greater risk.

Quick Demo

The Tyndall effect is a quick testthat differentiates a solutionfrom a heterogeneous mixture.Shine a thin beam of light (alaser is ideal) through a beakercontaining a solution such ascopper sulfate or sodium chlo-ride; the beam will not bevisible because of the small sizeof the solute particles (smallerthan 10�6 mm). However, whenyou shine light through amixture such as a weak milkcolloid or clay suspension, theparticles are large enough(greater than 10�6 mm) torefract the beam; thus, thebeam is plainly visible.

P

LS

67


Separating a MixtureVisual-Spatial Pass around a smallsandwich bag containing a mixture

such as styrofoam chunks, sand, coppersulfate, and iron filings and ask students todesign a branching flowchart that showshow the mixture could be separated withoutphysically picking out the pieces. They may

use the CRC Handbook of Chemistry andPhysics to develop their separation methods.After they have submitted their flowchart,they may proceed to actually carrying outthe experiment and writing it up.

P

LS

PP

LSP

ELL

LS

L2

P

LS

Separating MixturesMost matter exists naturally as mixtures. For students and scientists to gain athorough understanding of matter, it is very important to be able to do the reverseof mixing, that is, to separate mixtures into their component substances. Becausethe substances in a mixture are physically combined, the processes used to sep-arate a mixture are physical processes that are based on the difference in phys-ical properties of the substances. Sometimes it is very easy to separate a mixture;separating a mixture of pennies and nickels is not a difficult task. More difficultwould be separating a mixture of sand and iron filings. Or would it be? Thedemonstration illustrated in Figure 3-14 shows how the sand–iron mixture iseasily separated on the basis of the unique physical properties of the substancesinvolved. Numerous techniques have been developed that take advantage of dif-ferent physical properties in order to separate mixtures.

Heterogeneous mixtures composed of solids and liquids are easily separatedby filtration. Filtration is a technique that uses a porous barrier to separate asolid from a liquid. As Figure 3-15 shows, the mixture is poured through apiece of filter paper that has been folded into a cone shape. The liquid passesthrough, leaving the solids trapped in the filter paper.


Figure 3-14

The physical properties of theiron filings on the plate allowthem to be easily separatedfrom the sand using a magnet.

Separating Ink DyesApplying Concepts Chromatography is animportant diagnostic tool for chemists. Manytypes of substances can be separated and ana-lyzed using this technique. In this experiment, youwill use paper chromatography to separate thedyes in water-soluble black ink.

Materials 9-oz wide-mouth plastic cups (2);round filter paper; 1⁄4 piece of 11-cm round filterpaper; scissors; pointed object, approximately 3–4mm diameter; water-soluble black felt pen ormarker

Procedure 1. Fill one of the wide-mouth plastic cups with

water to about 2 cm from the top. Wipe offany water drops on the lip of the cup.

2. Place the round filter paper on a clean, drysurface. Make a concentrated ink spot in thecenter of the paper by firmly pressing the tipof the pen or marker onto the paper.

3. Use a sharp object to create a small hole,approximately 3–4 mm or about the diameterof a pen tip, in the center of the ink spot.

4. Roll the 1/4 piece of filter paper into a tightcone. This will act as a wick to draw the ink.Work the pointed end of the wick into thehole in the center of the round filter paper.

5. Place the paper/wick apparatus on top of thecup of water, with the wick in the water. The

water will move up the wick and outwardthrough the round paper.

6. When the water has moved to within about1 cm of the edge of the paper (about 20 min-utes), carefully remove the paper from thewater-filled cup and put it on the empty cup.

Analysis1. Make a drawing of the round filter paper and

label the color bands. How many distinct dyescan you identify?

2. Why do you see different colors at differentlocations on the filter paper?

3. How does your chromatogram compare withthose of your classmates who used other typesof black felt pens or markers? Explain the differences.

miniLAB

68

Purpose To separate a mixture by paperchromatography

Process SkillsApplying concepts, collecting andinterpreting data, comparing andcontrasting, observing and inferring

Safety PrecautionsBe sure students wear safetygoggles and aprons.

Teaching Strategies• Remind students to handle the

filter paper as little as possible.The oil from their fingers willdistort the results.

• Any size of round filter paper willwork. Green and yellow dyesseparate best if the paper is rela-tively large in diameter.

• Use several different types ofblack felt pens and black markers.Each brand and type has differentink combinations. This makes itmore interesting when studentscompare their chromatograms.The inks must be water soluble.

Expected ResultsAs the water spreads out on thepaper, different dyes in the ink willspread out from the center and bedeposited on the filter paper atdifferent distances from the center.

Analysis1. Drawings should resemble the

miniLab photo with correctlabels.

2. Different components of theink have varying attraction forthe filter paper. Therefore, thecolors that comprise the inkwill be deposited at differentdistances from the center ofthe paper.

3. Answers will vary. Differentmakes and types of black inkhave different dyes in them.

Skill Have students repeatthe experiment using ethanol andpermanent markers. Have themwrite a summary of both experi-ments in which they compare andcontrast the results. L2

P

LS


P

LS

miniLAB


ChemLab and MiniLab Worksheets, p. 9

Small-Scale Laboratory Manual,pp. 9–12

Forensics Lab Manual, pp. 1–12 L2

P

LS

L2

P

LS

L2

P

LS

CD-ROMChemistry: Matter and ChangeExploration: Separating MixturesExperiment: Metal Alloys

Most homogeneous mixtures can be separated by distillation. Distillationis a separation technique that is based on differences in the boiling points ofthe substances involved. In distillation, a mixture is heated until the substancewith the lowest boiling point boils to a vapor that can then be condensed intoa liquid and collected. When precisely controlled, distillation can separate sub-stances having boiling points that differ by only a few degrees.

Did you ever make rock candy as a child? Making rock candy from a sugarsolution is an example of separation by crystallization. Crystallization is a sep-aration technique that results in the formation of pure solid particles of a sub-stance from a solution containing the dissolved substance. When the solutioncontains as much dissolved substance as it can possibly hold, the addition ofa tiny amount more often causes the dissolved substance to come out of solu-tion and collect as crystals on some available surface. In the rock candy exam-ple, as water evaporates from the sugar–water solution, the sugar is left behindas a solid crystal on the string. Crystallization produces highly pure solids.

Chromatography is a technique that separates the components of a mix-ture (called the mobile phase) on the basis of the tendency of each to travelor be drawn across the surface of another material (called the stationaryphase). The miniLAB in this section describes how you can separate a solu-tion such as ink into its components as it spreads across a stationary piece ofpaper. The separation occurs because the various components of the inkspread through the paper at different rates.

3.3 Mixtures of Matter 69

Figure 3-15

Filtration is a common techniqueused to remove impurities fromdrinking water. Clean waterpasses through the porous filter

, leaving behind the impuritiesthat can be easily discarded .ba


15. How do mixtures and substances differ?

16. Consider a mixture of water, sand, and oil. Howmany phases are present? How could you separatethis mixture into individual substances?

17. Classify each of the following as either a hetero-geneous or homogeneous mixture.

a. orange juiceb. tap waterc. steel (a blend of iron and carbon)d. aire. raisin muffin

18. Thinking Critically When 50 mL of ethanol ismixed with 50 mL of water, a solution forms. Thevolume of the final solution is less than 100 mL.Propose an explanation for this phenomenon.(Hint: Consider what you know about the spacebetween particles in liquids.)

19. Applying Concepts Describe the separationtechnique that could be used to separate each ofthe following mixtures.

a. two colorless liquidsb. a nondissolving solid mixed with a liquidc. red and blue marbles of same size and mass

a b


Kinesthetic Set out fourunknowns in bottles: three of

the bottles are solutions (salt water,sugar water, a very dilute milkmixture) and one is a puresubstance (distilled water). Ask thestudents to determine which of theunknowns is a pure substance.

ReteachInterpersonal Have teamsof students develop a concept

map on an acetate sheet or largesheet of paper. The map shouldshow the relationships among thefollowing terms: matter, substance,heterogeneous mixture, solid,liquid, gas, vapor, physical change,chemical change, homogeneousmixture, solution, alloy.

Skill Set up samples ofsolutions, colloids, and suspensionsin dialysis bags or tubing (with theends tied) and suspend them inbeakers of distilled water. Askstudents to classify the samples andsupport their classifications withdiagrams or written explanations intheir portfolios. Solutions haveparticles small enough to fitthrough the pores of a dialysistube. This will be evident by thecoloration of the distilled wateroutside the dialysis tubing (if youare using a species with color,such as copper sulfate) or bytesting with a conductivity appa-ratus (if you are using a colorlessspecies, such as sodium chloride).

PP

LS

L2

P

LS

AssessmentAssessmentP

COOP LEARN

LS

L2

P

LS

L2

P

LS


15. Substances have a constantcomposition, mixtures do not. Eachsubstance in a mixture retains itsown properties, whereas the prop-erties of a substance are differentfrom those of the elements thatcomprise it.

16. There are three distinct phases,water, sand, and oil. The sand

could be separated from the oiland water by filtration. The oil andwater could be separated bypouring the oil off the top of thewater, or by distillation.

17. a. heterogeneous; b. homoge-neous; c. homogeneous;d. homogeneous;e. heterogeneous

18. Particles of liquids have spacebetween them. When the twoliquids mix, particles of one liquidfit between particles of the otherliquid.

19. a. distillationb. filtrationc. manually separating the

marbles by color 69

70

3.4Section

1 Focus


2 Teach

P

ELL

LS

L1

P

LS


Section 3.4 Elements and Compounds

Objectives• Distinguish between ele-

ments and compounds.

• Describe the organizationof elements on the periodictable.

• Explain how all compoundsobey the laws of definiteand multiple proportions.

Vocabularyelementperiodic tablecompoundlaw of definite proportionspercent by masslaw of multiple proportions

To this point you’ve examined many of the properties of matter. You’ve alsolearned how scientists have organized, classified, and described matter byarranging it into various subcategories of components. But there remainsanother fundamental level of classification of matter: the classification of puresubstances as elements or compounds.

ElementsRecall that earlier in this chapter you considered the diversity of your sur-roundings in terms of matter. Although the diversity is astounding, in realityall matter can be broken down into a relatively small number of basic build-ing blocks called elements. An element is a pure substance that cannot beseparated into simpler substances by physical or chemical means. On Earth,91 elements occur naturally. Copper, oxygen, and gold are examples of nat-urally occurring elements. There are also several elements that do not existnaturally but have been developed by scientists.

Each element has a unique chemical name and symbol. The chemical sym-bol consists of one, two, or three letters; the first letter is always capitalizedand the remaining letter(s) are always lowercase. Why has so much effort beengiven to naming the elements? The names and symbols of the elements areuniversally accepted by scientists in order to make the communication ofchemical information possible.

The 91 naturally occurring elements are not equally abundant. For exam-ple, hydrogen is estimated to make up approximately 75% of the mass of theuniverse. Oxygen and silicon together comprise almost 75% of the mass ofEarth’s crust, while oxygen, carbon, and hydrogen account for more than 90%of the human body. Francium, on the other hand, is one of the least abundantnaturally occurring elements. It is estimated that there is probably less than20 grams of francium dispersed throughout Earth’s crust. To put that into per-spective, the total mass of francium is approximately equal to the mass of yourpencil or pen.

A first look at the periodic table As many new elements werebeing discovered in the early nineteenth century, chemists began to seepatterns of similarities in the chemical and physical properties of par-ticular sets of elements. Several schemes for organizing the elementson the basis of these similarities were proposed, with varying degreesof success. In 1869, the Russian chemist Dmitri Mendeleev made asignificant contribution to the effort. Mendeleev devised the chartshown in Figure 3-16, which organized all of the elements that wereknown at the time into rows and columns based on their similaritiesand their masses. Mendeleev’s organizational table was the first ver-sion of what has been further developed into the periodic table of ele-ments. The periodic table organizes the elements into a grid ofhorizontal rows called periods and vertical columns called groups orfamilies. Elements in the same group have similar chemical and phys-ical properties. The table is called “periodic” because the pattern ofsimilar properties repeats as you move from period to period.

One of the brilliant aspects of Mendeleev’s original table was thatits structure could accommodate elements that did not even exist at

Figure 3-16

Although many early scientistshave contributed to the modernorganization of the elements,Mendeleev’s system of rows andcolumns was a revolutionaryadvancement.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

,a d

ivis

ion

of th

e M

cGra

w-H

ill C

ompa

nies

,Inc

.



Section Focus Transparency 12Common Elements

and Compounds

Use with Chapter 3, Section 3.4

Abundance of Elements in Earth’s Crust

Oxygen

49.2%

Silicon

25.7%

Aluminum

8.1%

Iron4.7%

Calcium 3.4%

Sodium 2.6%

Potassium 2.4%

Magnesium 1.9%Other elements 2.6%

Which element is the most abundant in Earth’s crust?

What are some common items that are made up of some

of these elements?

1

2

Focus Transparency

MMEETING EETING IINDIVIDUAL NDIVIDUAL NNEEDS EEDS MEETING INDIVIDUAL NEEDS

Visual-Spatial Decide which of theelements’ symbols and name spellings

you wish your students to know (generally50 to 60 of the more commonly usedelements). Have students make flashcards

with the name of the element on one sideand its corresponding symbol on the back.Provide some class time for students to quizeach other using the flashcards.

P

ELL

LS

L1

P

LS

Learning Disabled

VIDEODISCCosmic ChemistryDisc 3, Side 6 and Disc 4, Side 8Still: Elements

{`@±Å‘}

{`@±ë’}

{`@±°÷}

Heterogeneousmixtures

dirt, blood,milk

lemonade, gasoline,steel

oxygen, gold,iron

salt, baking soda,sugar

Homogeneousmixtures Elements Compounds

Matter

Mixtures

Physicalchanges

Chemicalchanges

Pure substances

the time. Notice the blank spots in Mendeleev’s table. By analyzing the sim-ilarities among the elements and their pattern of repetition, Mendeleev wasable to predict the properties of elements that were yet to be discovered.

In most cases, Mendeleev’s predictions (and the blanks in the table)closely matched the characteristics of new elements as they were discovered.Figure 3-18 on pages 72–73 shows samples of the elements in their arrange-ment in the periodic table. The standard modern version of the periodic tableincludes more than 100 elements. You’ll study the periodic table in greaterdetail later in this textbook. In fact, the periodic table remains a dynamic toolas scientists continue to discover new elements.

CompoundsTake a moment to recall what you have learned about the organization of mat-ter, using Figure 3-17 as a guide. You know that matter is classified as puresubstances and mixtures. As you learned in the previous section, mixtures canbe homogeneous or heterogeneous. You also know that elements are pure sub-stances that cannot be separated into simpler substances. There is yet anotherclassification of pure substances—compounds. A compound is a combina-tion of two or more different elements that are combined chemically. Mostof the substances that you are familiar with and, in fact, much of the matterof the universe are compounds. Water, table salt, table sugar, and aspirin areexamples of common compounds.

Today, there are approximately 10 million known compounds, and newcompounds continue to be developed and discovered at the rate of about100 000 per year. Can you recall some of the medicinal compounds that havemade headlines in recent years? There appears to be no limit to the numberof compounds that can be made or that will be discovered. Considering thisvirtually limitless potential, several organizations have assumed the task ofcollecting data and indexing the known chemical compounds. These organi-zations maintain huge databases that allow researchers to access informationon existing compounds. The databases and retrieval tools enable scientists tobuild the body of chemical knowledge in an efficient manner.

The chemical symbols of the periodic table make it easy to write the for-mulas for chemical compounds. For example, table salt, or sodium chloride,is composed of one part sodium (Na) and one part chlorine (Cl), and its chem-ical formula is NaCl. Water is composed of two parts hydrogen (H) to one partoxygen (O), and its formula is H2O.

3.4 Elements and Compounds 71

Figure 3-17

The concept of matter is far-reaching and can be overwhelm-ing. But, when broken down asshown here, it becomes clearhow elements, compounds, sub-stances, and mixtures define allmatter.

71

Pages 68–711(A), 4(C), 4(D), 6(C), 11(A)

Quick Demo

Using aHoffman apparatus, show theelectrolysis of water empha-sizing the constant 2:1 ratio ofthe volumes of hydrogen tooxygen. You may also wish todrain off a test-tube amount ofeach gas and perform a lightedsplint test on the hydrogen (itbarks) and a glowing splinttest on the oxygen (it relights).P

LS


Elementary PatternsIntrapersonal Have studentsresearch the work of scientists who,

like Mendeleev, worked in the area ofassigning meaningful patterns among theelements. Some of these scientists includeDobereiner, Newlands, Meyer, Moseley,and Seaborg.

P

LS

L2

P

LS


Study Guide for Content Mastery,pp. 17–18




P

ELL

LS

L2

P

LS

P

ELL

LS

L1

P

LS

L2

P

LS

L2

P

LS


IA1

IIA2

IIIB IVB VB VIB VIIB VIII3 4 5 6 7 8 9

1,01 H

6,93 Li

23,011 Na 24,3

12 Mg

39,119 K

85,537 Rb

132,955 Cs

22387 Fr

22789 Ac

138,957 La

23290 Th

140,158 Ce

23191 Pa

140,959 Pr

23892 U

144,260 Nd

23793 Np

14561 Pm

9,04 Be

40,120 Ca

87,638 Sr

137,356 Ba

22688 Ra

45,021 Sc

88,939 Y

138,957 La

22789 Ac

47,922 Ti

91,240 Zr

178,572 Hf

261104 Rf

50,923 V

92,941 Nb

180,973 Ta

262105 Db

52,024 Cr

95,942 Mo

183,874 W

266106 Sg

54,925 Mn

9843 Tc

186,275 Re

264107 Bh

55,826 Fe

101,144 Ru

190,276 Os

269108 Hs

58,927 Co

102,945 Rh

192,277 Ir

268109 Mt

22 min 1600 a 22 a 65 s 34 s 21 s 440 ms

4,2·106a

2,1·106a1,4·1010a 3,3·104a 4,5·109a22 a

18 a

9,3 s 70 ms

1

2

3

4

5

6

7

Periodic Table

Figure 3-18

The periodic table shown aboveillustrates samples of many ofthe elements. Be sure to use theperiodic table on pages 156-157for reference throughout yourchemistry course.

72

ReinforcementInterpersonal Reinforcestudents’ knowledge of

elemental symbols by playing“Bowling for Elements.” Insert tenelement flashcards in pinlikeformation in pockets of a largecardboard or on the chalkboard.Divide the class into teams andhave individuals take turns namingas many of the element “pins” bymoving from the lead pin to anycontiguous pin. Keep score as inbowling.

ExtensionIntrapersonal DmitriMendeleev (1834–1907) was

a delegate at the First InternationalChemistry Congress in 1860, andfrom that experience he began theundertaking that would immor-talize him in the history of chem-istry. Have students use the Internetand other resources to learn aboutthe meetings for chemists andscientists that take place today. L2

P

LS

P

LSP

COOP LEARN

LS

P

ELL

LS

L1

P

LS

Pages 72–734(D)

Our understanding of the elements haschanged drastically in the past 2500years. The ancient Greek philosophersbelieved that all the elements of the uni-verse were combinations of water, air,earth, and fire. Aristotle suggested a

fifth element, “aether,” of which all theheavens were made. The philosopherDemocritus (470–380 B.C.) was the first tobelieve that all matter consisted of tinyparticles and coined the term “atomos”meaning “indivisible.”

Egyptian practices in chemistry com-bined with Greek philosophy and mathe-matics to form the science of “khemia.”The Arabs inherited these traditions andplaced the “al-“ before the name, form-ing the pseudoscience “alchemy.”

The History of Elements

VIDEODISCCosmic ChemistryDisc 3, Side 6 and Disc 4, Side 8Still: Periodic table

{`@±¡ÿ}

{`@±—Ÿ}


VIIIA18

IB IIB10 11 12

IIIA IVA VA VIA VIIA13 14 15 16 17

24494 Pu

150,462 Sm

24395 Am

152,063 Eu

24796 Cm

157,364 Gd

24797 Bk

158,965 Tb

25198 Cf

162,566 Dy

25299 Es

164,967 Ho

257100 Fm

167,368 Er

258101 Md

168,969 Tm

259102 No

173,070 Yb

262103 Lr

175,071 Lu

58,728 Ni

106,446 Pd

195,178 Pt

273110

63,529 Cu

107,947 Ag

197,079 Au

272111

65,430 Zn

112,448 Cd

200,680 Hg

69,731 Ga

114,849 In

204,481 Tl

72,632 Ge

118,750 Sn

207,282 Pb

74,933 As

121,851 Sb

209,083 Bi

79,034 Se

127,652 Te

20984 Po

79,935 Br

126,953 I

21085 At

83,836 Kr

27,013 Al 28,1

14 Si 31,015 P 32,1

16 S 35,517 Cl 39,9

18 Ar

10,85 B 12,0

6 C 14,07 N 16,0

8 O 19,09 F 20,2

10 Ne

4,02 He

131,354 Xe

22286 Rn

277112

102 a 8,1 h

1,6·107a8,0·107a 7400 a 1400 a 900 a 472 d 101 d 52 d 58 min 3,6 h

3,8 d

118 ms 1,5 ms 0,24 ms

of the Elements

73

Visual LearningVisual-Spatial Have thestudents use the periodic table

to determine the number ofelements that are gaseous, liquid,solid, metallic, and radioactive atroom temperature.

Skill Have students use theCRC Handbook of Chemistry andPhysics (section on element infor-mation) to research the followingsample questions about theelements.• How many elements are named

for people? Countries? Cities orstates?

• How many elements are namedfor mythological figures or gods?

• What town has four elementsnamed for it?

• What elements were known toancient humans?

• What elements were discoveredbefore 1800? Between 1801 and1900? Between 1901 and thepresent?

Ask the students to choose oneparticular category and portray theinformation graphically. L2

P

LS


L2

P

LS

Alchemists sought to find a mysterioussubstance that could be taken apart andrecombined to form more precious ele-ments, such as gold. Although the prac-tice of alchemy was a dead end in itself,much useful chemical information and

many processes were stumbled upon.Early Chinese philosophers believed

that all materials cycle through five fun-damental stages: earth, wood, fire,metal, and water. Each step of the cycleled to a state of greater order. For

instance, the earth allows a tree to grow,which in turn can be chopped down andburned to transform metals. In the heat-ing process, condensation provides thewater to renew the cycle.

P

LS

Unlike elements, compounds can be broken down into simpler substancesby chemical means. In general, compounds that naturally occur are more sta-ble than the individual component elements. To separate a compound into itselements often requires external energy such as heat or electricity. Figure 3-19shows the apparatus used to produce the chemical change of water into its com-ponent elements of hydrogen and oxygen through a process called electrolysis.Here, one end of a long platinum electrode is exposed to the water in the tubeand the other end is attached to a power source. An electric current splits waterinto hydrogen gas in the compartment on the right and oxygen gas in the com-partment on the left. Because water is composed of two parts hydrogen and onepart oxygen, there is twice as much hydrogen gas than oxygen gas.

The properties of a compound are different from those of its componentelements. The example of water in Figure 3-19 illustrates this fact. Water isa stable compound that is liquid at room temperature. When water is broken

down into its components, it is obvious that hydro-gen and oxygen are dramatically different than theliquid they form when combined. Oxygen andhydrogen are tasteless, odorless gases that vigor-ously undergo chemical reactions with many ele-ments. This difference in properties is a result of achemical reaction between the elements. Figure 3-20 shows the component elements (sodium andchlorine) of the compound commonly called tablesalt (sodium chloride). When sodium and chlorinereact with each other, the compound sodium chlo-ride is formed. Note how different the properties ofsodium chloride are from its component elements.Sodium is a highly reactive element that fizzes andburns when added to water. Chlorine is a poison-ous, pale green gas. Sodium chloride, however, isa white, unreactive solid that flavors many of thefoods you eat.


Figure 3-19

This classic apparatus, called aHoffman apparatus, and othersimilar designs are used to sepa-rate water into its components.

Figure 3-20

Compounds such as sodium chlo-ride (table salt) are oftenremarkably different from thecomponents that comprise them.

Sodium

Chlorine

Sodiumchloride

74

EnrichmentIntrapersonal Have eachstudent “adopt” an element

and prepare a report on the proper-ties, uses, abundance, method ofmining and purifying, costs, andother pertinent information.Students can present a report per class, per week, or simply be“on-call” as the resident expert onthat element when the discussionmerits it. L2

P

LS

Pages 74–752(C), 4(C), 5(A)

Internet Address Book

Note Internet addresses that you find useful in thespace below for quick reference.

VIDEODISCCosmic ChemistryDisc 2, Side 3

Movie: Electrolysis of Water 0:50 sDecomposition reaction

{d…iêT±u}Movie: Sodium Chloride 1:19 minA reaction forming sodium chloride

{`r•E£a‘}

Law of Definite ProportionsAn important characteristic of compounds is that the elements comprisingthem combine in definite proportions by mass. This observation is so funda-mental that it is summarized as the law of definite proportions. This lawstates that, regardless of the amount, a compound is always composed of thesame elements in the same proportion by mass. For example, consider thecompound table sugar (sucrose), which is composed of carbon, hydrogen, andoxygen. The analysis of 20.00 g of sucrose from a bag of sugar is given inTable 3-4. Note that in Column 1 the sum of the individual masses of the ele-ments equals 20.00 g, the amount of sucrose that was analyzed. This demon-strates the law of conservation of mass as applied to compounds: The massof the compound is equal to the sum of the masses of the elements that makeup the compound. Column 2 shows the ratio of the mass of each element tothe total mass of the compound as a percentage called the percent by mass.

percent by mass (%) ��mmas

asss

ofof

coemlem

poeunntd�� 100

Now let’s suppose you analyzed 500.0 g of sucrose isolated from a sampleof sugar cane. The analysis is shown in Table 3-5. Note in Column 2 that the percent by mass values equal those in Column 2 in Table 3-4. Compoundswith the same mass proportions must be the same compound; conversely,compounds with different mass proportions must be different compounds.Thus, you can conclude that, although the two samples of sucrose are fromdifferent sources, they have the same composition and they must be the samecompound.


Sucrose Analysis from Bag Sugar

Column 1 Column 2

Element Analysis by mass (g) Percent by mass (%)

Carbon 8.44 g carbon � 100 � 42.2% carbon

Hydrogen 1.30 g hydrogen � 100 � 6.50% hydrogen

Oxygen 10.26 g oxygen � 100 � 51.30% oxygen

Total 20.00 g sucrose � 100.0%

Table 3-4

Sucrose Analysis from Sugar Cane

Column 1 Column 2

Element Analysis by mass (g) Percent by mass (%)

Carbon 211.0 g carbon � 100 � 42.20% carbon

Hydrogen 32.5 g hydrogen � 100 � 6.50% hydrogen

Oxygen 256.5 g oxygen � 100 � 51.30% oxygen

Total 500.0 g sucrose � 100.00%

Table 3-5

HistoryCONNECTION

Antoine-Laurent Lavoisier(1743–1794) is recognized as

the father of modern chemistry.While his fellow scientists tried toexplain matter based on the ele-ments fire, earth, air, and water,Lavoisier performed some of thefirst quantitative chemical experi-ments. His data and observationsled to the statement of the lawof conservation of mass. He alsostudied the nature of combustionand devised a system of namingelements.

Lavoisier held many publicoffices in France in which heattempted to reform the Frenchmonetary and taxation systemand farming methods. He alsosupervised the French govern-ment’s manufacture of gunpow-der. During the Reign of Terrorthat followed the FrenchRevolution, Lavoisier and othermembers of Fermés Generaléwere arrested, tried, and con-demned to the guillotine.

�20.080.4

g4

sguc

Crose�

�20.010.3

g0

sguc

Hrose�

�20.1000.2g6sguc

Orose�

�5002.101g.0

sugcCrose�

�5003.02.

g5

sguc

Hrose�

�5002.506g.5

sguc

Orose�

75

Quick Demo

CAUTION:Perform this demo under ahood. Weigh any two similar-looking organic compounds oflow melting point (sucrose andlactic acid, for example) inseparate crucibles and recordthe mass on the board. Heateach one strongly to drive offthe hydrogen and oxygen inthe form of water until all thatis left is pure carbon. Reweighthe crucibles with the carbonresidue and calculate thepercentage of carbon in eachcompound. Ask students if thetwo compounds could be thesame. No, each has adifferent percentage ofcarbon. Next ask students ifthe percentage of carbon hadbeen the same in eachcompound, would that provethey were in fact the samecompound. No, not neces-sarily, because the percent-ages of the other elements inthe compound (hydrogenand oxygen in this case)could be different.

P

LS



Math Skills Transparency 3 and Master

P

ELL

LS

L2

P

LS

P

ELL

LS

L2

P

LS


PRACTICE PROBLEMS20. A 78.0-g sample of an unknown compound contains 12.4 g of hydro-

gen. What is the percent by mass of hydrogen in the compound?

21. If 1.0 g of hydrogen reacts completely with 19.0 g of fluorine, what isthe percent by mass of hydrogen in the compound that is formed?

22. If 3.5 g of X reacts with 10.5 g of Y to form the compound XY, what isthe percent by mass of X in the compound? The percent by mass of Y?

23. Two unknown compounds are tested. Compound I contains 15.0 g ofhydrogen and 120.0 g of oxygen. Compound II contains 2.0 g ofhydrogen and 32.0 g of oxygen. Are the compounds the same?

24. All you know about two unknown compounds is that they have thesame percent by mass of carbon. With only this information, can yoube sure the two compounds are the same?

Law of Multiple ProportionsCompounds composed of different elements are obviously different com-pounds. Can compounds that are composed of the same elements differ fromeach other? The answer is yes because those different compounds have dif-ferent mass compositions. The law of multiple proportions states that whendifferent compounds are formed by a combination of the same elements, dif-ferent masses of one element combine with the same relative mass of the otherelement in a ratio of small whole numbers. Ratios compare the relativeamounts of any items or substances. The comparison can be expressed usingnumbers separated by a colon or as a fraction. With regard to the law of mul-tiple proportions, ratios express the relationship of elements in a compound.

The two distinct compounds water (H2O) and hydrogen peroxide (H2O2)illustrate the law of multiple proportions. Each compound contains the sameelements (hydrogen and oxygen). Water is composed of two parts hydrogen(the element that is present in the same amount in both compounds) to onepart oxygen (the element that is present in different amounts in both com-pounds). Hydrogen peroxide is composed of two parts hydrogen and two partsoxygen. Hydrogen peroxide differs from water in that it has twice as muchoxygen. When we compare the mass of oxygen in hydrogen peroxide to themass of oxygen in water, we get the ratio 2:1.

In another example, copper (Cu) reacts with chlorine (Cl) under differentsets of conditions to form two different compounds. Table 3-6 provides ananalysis of their composition. Note that the two copper compounds must bedifferent because they have different percents by mass. Compound I contains64.20% copper; compound II contains 47.27% copper. Compound I contains35.80% chlorine; compound II contains 52.73% chlorine.

Figure 3-21

Bar graph compares the rela-tive masses of copper and chlo-rine in Compound I and bargraph compares the relativemasses of copper and chlorine inCompound II. A comparisonbetween the relative masses ofcopper in both compoundsshows a 2:1 ratio.

b

a

Analysis Data of Two Copper Compounds

Mass copper (g) Mass chlorine (g) Mass ratioin 100.0 g of in 100.0 g of

Compound % Cu % Cl compound compound ��mmaassss

CCul��

I 64.20 35.80 64.20 35.80 1.793 g Cu/1 g Cl

II 47.27 52.73 47.27 52.73 0.8964 g Cu/1 g Cl

Table 3-6

Compound I

Mas

s (g

)

Cu

Cl

1.000

2.000

Compound II

Mas

s (g

)

Cu Cl

1.000

2.000

Mass RatioComparison

Mas

s (g

)

1.000

2.000

II

I

a

b

c

For more practice withpercent by mass andlaw of definite proportions, go to

Supplemental PracticeProblems in Appendix A.

Practice!

c

76


Visual-Spatial Havestudents draw diagrams

featuring atoms and molecules thatshow packing arrangements inheterogeneous mixtures, solutions,and pure substances.

P

ELL

LS

L2

P

LS

Pages 76–772(C), 3(E), 4(C)

PROBLEMSHave students refer to AppendixD for complete solutions toPractice Problems.20. 15.9%21. 5.0%22. 25% X and 75% Y23. When the composition by

mass percentage is calcu-lated for both compounds,it is found that thecomposition is not thesame for the twocompounds; therefore,they must be different.

24. No, you cannot be sure.Having the same masspercentage of a singleelement does not guar-antee that the composi-tion of each compound isthe same.


Same Elements, Major DifferencesVisual-Spatial Have students use theCRC Handbook of Chemistry and

Physics to look up the properties ofcompounds that exemplify the law ofmultiple proportions (for example, copper(I)

chloride and copper(II) chloride; hydrogenperoxide and water). Have them organizethe information in reference tables so theycan clearly see distinctions between the twocompounds.

P

LS

L2

P

LS

Compare the ratio of the mass of copper to the mass of chlorine for eachcompound (see the last column of Table 3-6 and Figure 3-21). You’ll noticethat the mass ratio of copper to chlorine in compound I (1.793) is two timesthe mass ratio of copper to chlorine in compound II (0.896).

� � 2.000

As the law of multiple proportions states, the different masses of copper thatcombine with a fixed mass of chlorine in the two different copper com-pounds, shown in Figure 3-22, can be expressed as a small whole-numberratio, in this case 2:1.

Considering that there is a finite number of elements that exist today andan exponentially greater number of compounds that are composed of theseelements under various conditions, it becomes clear how important the lawof multiple proportions is in chemistry.

�01..8799634

gg

CCuu//gg

CCll

�mass ratio compound I��mass ratio compound II



25. How are elements and compounds similar? Howare they different?

26. What is the basic organizing feature of the peri-odic table of elements?

27. Explain how the law of definite proportionsapplies to compounds.

28. What type of compounds are compared in the lawof multiple proportions?

29. Thinking Critically Name two elements thathave properties similar to those of element potas-sium (K). To those of krypton (Kr).

30. Interpreting Data Complete the following tableand then analyze the data to determine if com-pounds I and II are the same compound. If thecompounds are different, use the law of multipleproportions to show the relationship between them.

Analysis Data of Two Iron Compounds

Compound Total mass (g) Mass Fe (g) Mass O (g) Mass % Fe Mass % O

I 75.00 52.46 22.54

II 56.00 43.53 12.47

Figure 3-22

Analyses of the mass ratios ofthe two copper chloride com-pounds shown here indicatethat they are indeed differentcompounds. The calculated massratio of compound I to com-pound II is 2.000 and fits thedefinition of the law of multipleproportions.

ReteachVisual-Spatial Students mayfind it easier to memorize a

triangular arrangement of matterfrom most general at the bottom ofthe pyramid to most specific(element, compound, solution,heterogeneous mixture) at the topof the pyramid. Also, as you movefrom right to left on the base of thepyramid, classification becomesmore ordered.

ExtensionKinesthetic Give eachstudent a 10 cm � 10 cm

“information square” on which theydescribe themselves by a categorysuch as name, address, height, haircolor, eye color, interests, pets,number of siblings. Have them put asmall picture of themselves in thecenter. Then pass out reduced copiesof the completed squares and ask thestudents to arrange the squares intoas many meaningful patterns aspossible. Once they have decided ona pattern, students should pastedown their squares and describetheir pattern in a presentation. Thisassignment may also be done as anentire class using the originalsquares and generating discussionabout the best placement of eachsquare. In order to obtain enoughsquares, consider combining classes.

Skill Clip photos of variousmixtures from magazines or othersources and have students identifythem as heterogeneous mixtures,solutions, or pure substances invarious phases.

P

ELL

LS

L2

P

LS


P

LSP

COOP LEARN

LS

P

ELL

LS

L1

P

LS

P

ELL

LS

L1

P

LS


25. Compounds are composed ofelements and can be brokendown. Elements cannot be brokendown into simpler substances.

26. The periodic table of elements isorganized by similarities in phys-ical and chemical properties.

27. The law of definite proportions

describes the constant compositionof a substance.

28. The law of multiple proportionsrelates the compositions of twocompounds composed of the sameelements.

29. Elements in group 1A have proper-ties similar to K. Elements in group

8A have properties similar to Kr.30. Compound I mass percent Fe �

69.95%; mass percent O � 30.05%.Compound II mass percent Fe �

77.73%; mass percent O � 22.27%.The compounds are not the same.The mass ratio of compound 1 tocompound 2 is 2:3.

77

Pre-Lab

Pre-Lab

1. Read the entire CHEMLAB.

2. Prepare all written materials that you will take intothe laboratory. Be sure to include safety precau-tions, procedure notes, and a data table in which torecord your observations.

3. Define the terms physical property and chemicalproperty. Give an example of each.

4. Form a hypothesis regarding what you mightobserve if a. a chemical change occurs.b. a physical change occurs.

5. Distinguish between a homogeneous mixture and aheterogeneous mixture.

Procedure

1. Obtain 8 cm of copper wire. Rub the copper wirewith the sandpaper until it is shiny.

2. Measure approximately 25 mL AgNO3 (silvernitrate) solution into a 50-mL beaker. CAUTION:Do not allow to contact skin or clothing.

3. Make and record an observation of the physicalproperties of the copper wire and AgNO3solution.


Safety Precautions

• Always wear safety goggles, gloves, and lab apron.• Silver nitrate is toxic and will harm skin and clothing.• Use caution around a flame.

ProblemIs there evidence of a chemi-cal reaction between copperand silver nitrate? If so, whichelements reacted and what isthe name of the compoundthey formed?

Objectives• Observe the reactants as

they change into product.• Separate a mixture by

filtration.• Predict the names of the

products.

Materialscopper wireAgNO3 solutionsandpaperstirring rod50-mL graduated

cylinder50-mL beakerfunnel

filter paper250-mL Erlenmeyer

flaskring standsmall iron ringplastic petri dishpaper clipBunsen burnertongs

Matter and ChemicalReactionsOne of the most interesting characteristics of matter, and one that

drives the study and exploration of chemistry, is the fact thatmatter changes. By examining a dramatic chemical reaction, such asthe reaction of the element copper and the compound silver nitratein a water solution, you can readily observe chemical change.Drawing on one of the fundamental laboratory techniques intro-duced in this chapter, you can separate the products. Then, you willuse a flame test to confirm the identity of the products.

CHEMLAB 3

Reaction Observations

Time(min)

Observations

78

Procedure• The lengths of wire can be cut ahead.• Copper coil can be allowed to sit in AgNO3

solution overnight.• Darken room to view flame color.

3CHEMLAB

Preparation Time AllotmentOne laboratory period

Process SkillsObserving and inferring,classifying

Safety PrecautionsBe sure students wear aprons andgoggles. Remind students to tieback long hair and use cautionaround a flame. Paper clip willremain hot for several minutes. Donot allow solutions to contact skinor clothing.

DisposalRinse filtrate down the drain withlots of water. The solid wastes may be collected for recyclingaccording to local regulations.

3. A physical property is a charac-teristic that can be observed ormeasured without changingthe substance’s composition—for example, color, shape, ormass. A chemical property isthe ability of a substance tocombine with or change intoone or more other substances—for example, reactivity withwater.

4. a. You might observe achange in color or odor, theevolution of heat or light,the absorption of energy,or the formation of a gas,liquid, or different solid. Adifferent product will form.

b. You might observe achange in shape or in phys-ical state, such as boiling,condensing, freezing,melting, evaporating,dissolving, or crystallizing.

5. A homogeneous mixture isone in which one or moresubstances are evenly distrib-uted throughout anothersubstance. A heterogeneousmixture is one in which thereis an observable separation ofcomponent substances.

P

LS

79

CHEMLAB 79

4. Coil the piece of copper wire to a length that willfit into the beaker. Make a hook on the end of thecoil to allow the coil to be suspended from thestirring rod.

5. Hook the coil onto the middle of the stirring rod.Place the stirring rod across the top of the beakerimmersing some of the coil in the AgNO3 solution.

6. Make and record observations of the wire and thesolution every five minutes for 20 minutes.

7. Use the ring stand, small iron ring, funnel,Erlenmeyer flask, and filter paper to set up a fil-tration apparatus. Attach the iron ring to the ringstand. Adjust the height of the ring so the end ofthe funnel is inside the neck of the Erlenmeyerflask.

8. To fold the filter paper, examine the diagrambelow. Begin by folding the circle in half, thenfold in half again. Tear off the lower right cornerof the flap that is facing you. This will help thefilter paper stick better to the funnel. Open thefolded paper into a cone. Place the filter papercone in the funnel.

9. Remove the coil from the beaker and dispose ofit as directed by your teacher. Some of the solidproduct may form a mixture with the liquid in thebeaker. Decant the liquid by slowly pouring itdown the stirring rod into the funnel. Solidproduct will be caught in the filter paper. Collectthe filtrate—the liquid that runs through the filterpaper—in the Erlenmeyer flask.

10. Transfer the clear filtrate to a petri dish.

11. Adjust a Bunsen burner flame until it is blue.Hold the paper clip with tongs in the flame untilno additional color is observed. CAUTION: Thepaper clip will be very hot.

12. Using tongs, dip the hot paper clip in the filtrate.Then, hold the paper clip in the flame. Record thecolor you observe.

Cleanup and Disposal

1. Dispose of materials as directed by your teacher.

2. Clean and return all lab equipment to its properplace.

3. Wash hands thoroughly.

Analyze and Conclude

1. Classifying Which type of mixture is silvernitrate in water? Which type of mixture is formedin step 6? Explain.

2. Observing and Inferring Describe the changesyou observed in step 6. Is there evidence achemical change occurred? Why?

3. Predicting Predict the products formed in step6. You may not know the exact chemical name,but you should be able to make an intuitiveprediction.

4. Using Resources Use resources such as the CRCHandbook of Chemistry and Physics, the MerckIndex, or the Internet to determine the colors ofsilver metal and copper nitrate in water. Comparethis information with your observations of thereactants and products in step 6.

5. Identifying Metals emit characteristic colors inflame tests. Copper emits blue-green light. Doyour observations in step 12 confirm the presenceof copper in the filtrate collected in step 9?

6. Communicating Express in words the chemicalequation that represents the reaction that occurredin step 6.

7. Compare your recorded obser-vations with those of several other lab teams.Explain any differences.

Real-World Chemistry

1. Analytical chemists determine the chemicalcomposition of matter. Two major branches ofanalytical chemistry are qualitative analysis—determining what is in a substance—and quanti-tative analysis—measuring how much substance.Research and report on a career as an analyticalchemist in the food industry.

Error Analysis

CHAPTER 3 CHEMLAB

Tear corner

Expected ResultsStep 3: Cu – reddish metal; AgNO3

–clear, colorless solutionStep 6: Solution will turn blue-green; grayish solid will “grow” onthe wire.Step 12: blue-green color

Analyze and Conclude1. homogeneous; heterogeneous

and homogeneous.2. A grayish solid formed on the

wire. The solution turned blue-green. Yes, a solid formed anda color change occurred.

3. silver and copper nitrate4. Silver metal is white to gray.

Copper nitrate is blue-green.5. Experimental results should

agree with blue-green light.6. Copper and silver nitrate solu-

tion react to form silver andcopper nitrate.

7. Copper wire may not havebeen clean. The better obser-vations will be more detailed.

Real-World Chemistry1. Answers will vary but may

include analysis of vitamincontent, flavors, preservatives,or calorie content.

Portfolio Have eachstudent place the laboratory reportfor this experiment in his or herportfolio. PP

LS

L2

P

LS


Pages 78–791(A), 2(A), 2(B), 2(D), 2(E), 5(A)


ChemLab and MiniLab Worksheets,pp. 10–12 L2

P

LS

80

Purpose Students will learn about efforts touse chemistry to produce qualitybuildings while decreasing theirnegative impact on the environment.

BackgroundWhile not always thought ofamong the top industries thatpollute the atmosphere, cementproduction is one of the mostenergy-intensive industries in theworld. This use of energy, alongwith chemical reactions involved inthe production of cement, releasehuge amounts of carbon dioxideand other greenhouse gases into theatmosphere every year. Annually,cement production releases asmuch CO2 as 350 million cars.

Researchers have found a wayto use a waste product of coal-burning power plants to decreasethe amount of cement used to makeconcrete. In addition to protectingthe environment, the properties ofthis waste product, known asflyash, lead to a stronger, moredurable concrete. Flyash starts outas impurities in coal. Since theimpurities cannot be burned, theyend up as ash. At high tempera-tures, they fuse and become glass.As the glass particles move at highspeeds with the gases releasedduring the burning of coal, the hotglass turns into tiny beads.

Teaching Strategies• Ask students to review the green-

house effect and to prepareposters showing how it maintainsthe temperatures on Earth.

• Ask students to debate the possi-bility of decreasing the amount ofconcrete used throughout theworld. Have them address theissue that the need for cement isexpected to double in the next 25years as developing countriesexpand their building.

• It takes between 1450 and 1600kg (3200 to 3500 lb) of raw mate-rials to produce about 907 kg

P

LS

(1 ton) of finished cement. Ask students toresearch and present other statistics related tocement production.

• Some people are concerned about the use offlyash. For example, there is some concernabout radioactivity. The EPA believes thatflyash does not constitute a significant riskthat is any greater than from the cement itreplaces. Ask students to find out about anyissues related to the use of flyash.

Investigating the Issue1. Answers will vary. Students should stress

the importance of finding industrialmethods that are safe for the environ-ment yet still meet the objectives.

2. Students may consider cost, availability,processing ease, and safety in theirdiscussions.

CHEMISTRY and

Society

Until the Industrial Revolution, the amount of car-bon dioxide (CO2) in the atmosphere was fairly con-stant. Since the Industrial Revolution, however, theburning of fossil fuels has contributed to a signifi-cant increase in the amount of carbon dioxide in theatmosphere. As the level of carbon dioxide increases,Earth gradually warms up. Too much CO2 in theatmosphere can change the conditions on Earth.

Another major source of carbon dioxide may bein the foundation of your building or on the side-walks near your school. The production of cement,the key ingredient in concrete, releases tremendousamounts of carbon dioxide into the atmosphere.Chemistry may allow engineers to build “greenbuildings,” that are still practical yet have less ofan impact on the environment.

Producing CementCement generally begins with a mixture of lime-stone and sand placed in a kiln, which heats it toabout 1480°C. As the mixture is heated, its chem-ical and physical properties change. After heating,the solid that remains is ground into a fine powder.This is cement. To make concrete, the cement ismixed with fine particles, such as sand, coarse par-ticles, such as crushed stone, and water.

During the production of cement, carbon diox-ide is released in two ways. First, when the lime-stone is heated it changes into lime and carbondioxide. Second, the electrical energy used to heatthe kiln is usually supplied by a power plant thatburns fossil fuels, such as coal. Fossil fuels alsorelease carbon dioxide and other substances.

Using FlyashOne way to reduce the amount of carbon dioxidereleased into the atmosphere is to find a replace-ment for cement in concrete. One such replacementis a substance known as flyash. Flyash is a wasteproduct that accumulates in the smokestacks ofpower plants when ground coal is burned. It is afine gray powder that consists of tiny glass beads.

Using flyash offers several advantages. Flyashordinarily is dumped in landfills. Replacing cementwith flyash can reduce CO2 emissions and prevent

tons of waste from piling up in landfills. Flyash alsoproduces better concrete. Traditional concrete hasweak zones where tiny cracks allow water to flowthrough. Flyash contains fine particles that fillspaces and keep moisture out. Flyash also protectsthe steel surrounding the concrete, makes the con-crete easier to work with, and extends the life of theconcrete structure. In fact, flyash is so reliable theRomans used natural materials similar to flyash tobuild the concrete dome of the Pantheon.

Solutions to environmental problems require awilling commitment from scientists, architects,builders, and owners to look for ways to builddurable structures and protect the environment.

1. Communicating Ideas Write a pamphlet forpeople who are building new homes tellingthem about the importance of green buildings.

2. Using the Internet Investigate issues thatinfluence the decision to use flyash. Discussthe advantages and disadvantages of flyash.

Investigating the Issue

Green Buildings

CHEMISTRY and

Society

Visit the Chemistry Web site at science.glencoe.com to find links to more information about flyash and green buildings.



Pages 80–813(B), 3(C), 4(A), 4(C), 4(D), 5(A),11(A)

Study Guide 81

CHAPTER STUDY GUIDE3

Vocabulary

Key Equations and Relationships

Summary3.1 Properties of Matter

• A substance is a form of matter with a uniform andunchanging composition.

• Physical properties can be observed without alteringa substance’s composition. Chemical propertiesdescribe a substance’s ability to combine with orchange into one or more new substances.

• Both physical and chemical properties are affected byexternal conditions such as temperature and pressure.

• The three common states of matter are solid, liquid,and gas.

3.2 Changes in Matter• A physical change alters the physical properties of a

substance without changing its composition.

• A chemical change, also known as a chemical reac-tion, involves a change in a substance’s composition.

• In a chemical reaction, reactants form products.

• The law of conservation of mass states that mass isneither created nor destroyed during a chemicalreaction; it is conserved.

3.3 Mixtures of Matter

• A mixture is a physical blend of two or more puresubstances in any proportion.

• Solutions are homogeneous mixtures.

• Mixtures can be separated by physical means.Common separation techniques include filtration,distillation, crystallization, and chromatography.

3.4 Elements and Compounds• Elements are substances that cannot be broken down

into simpler substances by chemical or physicalmeans.

• The elements are organized in the periodic table ofelements.

• A compound is a chemical combination of two ormore elements. Properties of compounds differ fromthe properties of their component elements.

• The law of definite proportions states that a com-pound is always composed of the same elements inthe same proportions.

• The law of multiple proportions states that if ele-ments form more than one compound, those com-pounds will have compositions that are small,whole-number multiples of each other.

• law of conservation of mass (p. 63)Massreactants � Massproducts

• percent by mass � �MMaasss

c

s

o

e

m

le

p

m

o

e

u

n

n

t

d� � 100

(p. 75)

• chemical change (p. 62)• chemical property (p. 57)• chromatography (p. 69)• compound (p. 71)• crystallization (p. 69)• distillation (p. 69)• element (p. 70)• extensive properties (p. 56)• filtration (p. 68 )• gas (p. 59)

• heterogeneous mixture (p. 67)• homogeneous mixture (p. 67)• intensive properties (p. 56)• law of conservation of mass

(p. 63)• law of definite proportions

(p. 75)• law of multiple proportions

(p. 76)• liquid (p. 58)

• mixture (p. 66)• percent by mass (p. 75)• periodic table (p. 70)• physical changes (p. 61)• physical property (p. 56)• solid (p. 58)• solution (p. 67)• states of matter (p. 58)• substance (p. 55)• vapor (p. 59)

Using the VocabularyTo reinforce chapter vocabulary,have students write a sentenceusing each term.

Review Strategies• Have students summarize the

differences between physical andchemical properties and physicaland chemical change and give anexample of each.

• Have students be able to use thesymbols of the most frequentlyused elements.

• Have students be able to classifymatter according to the schemegiven in the chapter.

• Problems from Appendix A or theSupplemental Problems bookletcan be used for review. L2

P

LS

L1

P

LS

L1

P

LS

L2

P

LS

P

ELL

LS

L2

P

LS

81

CHAPTERSTUDY GUIDE 3

Reviewing Chemistry is a compo-nent of the Teacher ClassroomResources package that wasprepared by The PrincetonReview. Use the Chapter 3review materials in this book toreview the chapter with yourstudents.

PortfolioPortfolio

Review the portfolio options that are pro-vided throughout the chapter. Encouragestudents to select one product that demon-strates their best work for the chapter. Havestudents explain what they have learned

and why they chose this example for place-ment into their portfolios. Additional port-folio options may be found in the ChallengeProblems booklet of the Teacher ClassroomResources. PP

LS

L2

P

LS

Portfolio Options

VIDEOTAPE/DVDMindJoggerVideoquizzesChapter 3: Matter––Properties andChanges

Have students work in groups as they play the videoquiz gameto review key chapter concepts.


Go to the Chemistry Web site at science.glencoe.com or use the Chemistry CD-ROM for additional Chapter 3 Assessment.

Concept Mapping31. Organize the following terms into a logical concept

map: state, physical properties, virtually incompress-ible, solid, gas, liquid, tightly packed particles, com-pressible, incompressible, particles far apart, looselypacked particles.

Mastering Concepts32. List three examples of substances. Explain why each

is a substance. (3.1)

33. List at least three physical properties of tap water. (3.1)

34. Identify each of the following as an extensive or inten-sive physical property. (3.1)

a. melting pointb. massc. densityd. length

35. “Properties are not affected by changes in temperatureand pressure.” Is this statement true or false? Explain.(3.1)

36. Classify each of the following as either solid, liquid,or gas at room temperature. (3.1)

a. milkb. airc. copperd. heliume. diamondf. candle wax

37. Classify each of the following as a physical propertyor a chemical property. (3.1)

a. aluminum has a silvery colorb. gold has a density of 19 g/cm3

c. sodium ignites when dropped in waterd. water boils at 100°Ce. silver tarnishesf. mercury is a liquid at room temperature

38. A carton of milk is pouredinto a bowl. Describe thechanges that occur in themilk’s shape and volume.(3.1)

39. Classify each of the follow-ing as a physical change or a chemical change. (3.2)

a. breaking a pencil in twob. water freezing and forming icec. frying an eggd. burning woode. leaves turning color in the fall

40. Is a change in phase a physical change or a chemicalchange? Explain. (3.2)

41. List four indicators that a chemical change has proba-bly taken place. (3.2)

42. Iron and oxygen combine to form iron oxide (rust).List the reactants and products of this reaction. (3.2)

43. Use Table 3-1 to identify a substance that undergoes aphase change as its temperature increases from �250°Cto �210°C. What phase change takes place? (3.2)

44. After burning for three hours, acandle has lost half of its mass.Explain why this example doesnot violate the law of conservationof mass. (3.2)

45. Describe the difference between aphysical change and a chemicalchange. (3.2)

46. Describe the characteristics of amixture. (3.3)

47. Describe a method that could be used to separate eachof the following mixtures. (3.3)

a. iron filings and sandb. sand and saltc. the components of ink d. helium and oxygen gases

48. “A mixture is the chemical bonding of two or moresubstances in any proportion.” Is this statement true orfalse. Explain.

CHAPTER ASSESSMENT##CHAPTER ASSESSMENT3

1.

2.

4. 5.3.

7. 8.6.

10. 11.9.

82

Concept Mapping31. 1. physical properties;

2. state; 3. solid; 4. liquid;5. gas; 6. tightly packedparticles; 7. loosely packedparticles; 8. particles farapart; 9. incompressible;10. virtually incompressible;11. compressible

Mastering Concepts32. Answers will vary. Water,

salt, and sugar are allsubstances. Each is asubstance because it has aunique and unchangingcomposition.

33. Answers will vary. Tapwater is colorless, a liquid,freezes at approximately0°C, and boils at approxi-mately 100°C.

34. a. intensive c. intensiveb. extensive d. extensive

35. The statement is false.Properties are affected bychanges in temperature,pressure. Specific exampleswill vary.

36. a. liquid d. gasb. gas e. solidc. solid f. solid

37. a. physical d. physical b. physical e. chemicalc. chemical f. physical

38. The volume of the milkremains unchanged. Milk,which is a liquid, conformsto the shape of itscontainer, thus the shape ofthe milk changes as it ispoured from the carton intothe bowl.

39. a. physical d. chemicalb. physical e. chemicalc. chemical

40. A change in phase is a physical changebecause the composition of thesubstance is not altered.

41. Probable indicators of a chemical reac-tion include a change in color, odor, ortemperature, and/or the productionof a gas or a solid upon mixing.

42. Iron and oxygen are the reactants,while iron oxide is the productformed. Iron � oxygen → iron oxide

CHAPTERASSESSMENT 3

All Chapter Assessment ques-tions and answers have beenvalidated for accuracy and suit-ability by The Princeton Review.


Chapter Assessment, pp. 13–18 Supplemental Problems, Ch. 3TestCheck SoftwareMindJogger VideoquizzesSolutions Manual, Ch. 3Chemistry Interactive CD-ROM, Ch. 3 quiz

L2

P

LS

Reviewing Chemistry: Mastering the TEKS, Ch. 3


83

Assessment 83

CHAPTER 3 ASSESSMENT

49. Which of the following are the same and which aredifferent? (3.3)

a. a substance and a pure substanceb. a heterogeneous mixture and a solutionc. a substance and a mixtured. a homogeneous mixture and a solution

50. Describe how a homogeneous mixture differs from aheterogeneous mixture. (3.3)

51. A chemistry professor has developed a laboratory taskto give her students practical experience using basicseparation techniques. She prepares a liquid solutionof water and another compound. Assuming you are astudent in the class, name the technique you would useto separate and identify the components. Give specificdetails of the method.

52. State the definition of an element. (3.4)

53. Name the elements contained in the following compounds. (3.4)

a. sodium chloride (NaCl) c. ethanol (C2H6O)b. ammonia (NH3) d. bromine (Br2)

54. How many naturally occurring elements are found onEarth? Approximately how many synthetic elementshave been identified? (3.4)

55. What was Dmitri Mendeleev’s major contribution tothe field of chemistry? (3.4)

56. Is it possible to distinguish between an element and acompound? Explain. (3.4)

57. How are the properties of a compound related to thoseof the elements that comprise it? (3.4)

58. How are the elements contained within a group on theperiodic table related? (3.4)

59. Which law states that a compound always contains thesame elements in the same proportion by mass? (3.4)

Mastering ProblemsProperties of Matter (3.1)60. A scientist is given the task of identifying an unknown

compound on the basis of its physical properties. Thesubstance is a white solid at room temperature.Attempts to determine its boiling point were unsuc-cessful. Using Table 3-1, name the unknown com-pound.

Conservation of Mass (3.2)61. A 28.0-g sample of nitrogen gas combines completely

with 6.0 g of hydrogen gas to form ammonia. What isthe mass of ammonia formed?

62. A substance breaks down into its component elementswhen it is heated. If 68.0 grams of the substance ispresent before it is heated, what is the combined massof the component elements after heating?

63. A 13.0-g sample of X combines with a 34.0-g sampleof Y to form the compound XY2. What is the mass ofthe reactants?

64. Sodium chloride can be formed by the reaction ofsodium metal and chlorine gas. If 45.98 g of sodiumcombines with an excess of chlorine gas to form116.89 g sodium chloride, what mass of chlorine gasis used in the reaction?

65. Copper sulfide is formed when copper and sulfur areheated together. In this reaction, 127 g of copper reactswith 41 g of sulfur. After the reaction is complete, 9 gof sulfur remains unreacted. What is the mass of cop-per sulfide formed?

Law of Definite Proportions (3.4)66. A 25.3-g sample of an unknown compound contains

0.8 g of oxygen. What is the percent by mass of oxy-gen in the compound?

67. Magnesium combines with oxygen to form magne-sium oxide. If 18.06 g of magnesium reacts com-pletely with 6.96 g of oxygen, what is the percent bymass of oxygen in magnesium oxide?

68. When mercury oxide is heated, it decomposes intomercury and oxygen. If 28.4 g of mercury oxidedecomposes, producing 2.0 g oxygen, what is the per-cent by mass of mercury in mercury oxide?

Law of Multiple Proportions (3.4)69. Carbon reacts with oxygen to form two different com-

pounds. Compound I contains 4.82 g carbon for every6.44 g of oxygen. Compound II contains 20.13 g carbonfor every 53.7 g of oxygen. What is the ratio of carbonto a fixed mass of oxygen for the two compounds?

Mixed ReviewSharpen your problem-solving skills by answering the following.

70. Which state of matter is the most compressible? Theleast? Explain why.

Solid Liquid Gas

49. a. same c. differentb. different d. same

50. Homogeneous mixtures contain asingle phase. Heterogeneous mixturesmay have many phases.

51. Using distillation, heat the solutionuntil the boiling point of the aqueouscomponent is reached, then note thattemperature. Boil away the aqueouscomponent and observe the remainingcomponent. Use a table such as 3-1 or

another resource to identify thecomponents based on the information obtained from the distillation process.

52. An element is a substance that cannotbe broken down into simplersubstances by physical or chemicalmeans.

53. a. sodium and chlorineb. nitrogen and hydrogenc. carbon, hydrogen, and oxygend. bromine

43. Oxygen undergoes a phasechange as its temperatureincreases from �250°C to�210°C. Solid oxygen meltsto form liquid oxygen at atemperature of �218°C.

44. The mass of the candle isconserved if you considerthe gaseous products fromthe reaction.

45. A physical change alters asubstance without changingits composition, while achemical change involves achange in composition.

46. Mixtures are a physicalblend of two or moresubstances in any propor-tion. Mixtures do not havea constant composition. Theproperties of the mixtureare largely those of itscomponent substances.

47. a. A magnet can be usedto draw the iron filingsfrom the sand.

b. Add water to themixture to dissolve thesalt. Filter the mixture toremove the sand, andthen boil off the waterso only the salt remains.

c. Paper chromatographyshould be used to sepa-rate the components ofthe ink. If enough ink isavailable, distillationmay also be used, but isfar more complicatedthan chromatography.

d. Cool the gas mixtureuntil it condenses, thendistill the condensate.

48. The statement is falsebecause mixtures are aphysical blend ofsubstances, not a chemicalbonding of substances.


Pages 82–832(C), 4(A), 4(B), 4(C), 4(D), 5(A),6(C), 11(A)

Energy Released by Carbon

Mass (g) Energy released (kJ)

1.00 33

2.00 66

3.00 99

4.00 132


71. Classify each of the following as a homogeneous mix-ture or a heterogeneous mixture. (3.3)

a. brass (an alloy of zinc and copper)b. a saladc. bloodd. powder drink mix dissolved in water

72. Phosphorus combines with hydrogen to form phos-phine. In this reaction, 123.9 g of phosphorus com-bines with excess hydrogen to produce 129.9 g ofphosphine. After the reaction, 310 g of hydrogenremains unreacted. What mass of hydrogen is used inthe reaction? What was the initial mass of hydrogenbefore the reaction?

73. A sample of a certain lead compound contains 6.46grams of lead for each gram of oxygen. A second sam-ple has a mass of 68.54 g and contains 28.76 g of oxy-gen. Are the two samples the same?

Thinking Critically74. Applying Concepts Air is a mixture of many

gases, primarily nitrogen, oxygen, and argon. Coulddistillation be used to separate air into its componentgases? Explain.

75. Interpreting Data A compound contains elementsX and Y. Four samples with different masses wereanalyzed, and the masses of X and Y in each samplewere plotted on a graph. The samples are labeled I, II,III, and IV.

a. Which samples are from the same compound? Howdo you know?

b. What is the approximate ratio of mass X to mass Yin the samples that are from the same compound?

c. What is the approximate ratio of mass X to mass Yin the sample(s) that are not from the same compound?

Writing in Chemistry76. Select a synthetic element and prepare a short written

report on its development. Be sure to cover recent dis-coveries, list major research centers that conduct thistype of research, and describe the properties of thesynthesized element.

77. Research the life of a scientist, other than Mendeleev,who contributed to the development of the modernperiodic table of elements. Write a brief biography of this person and detail his or her scientific accomplishments.

78. The results and interpretations of chemistry experi-ments and studies are recorded and published in liter-ally hundreds of scientific journals around the world.Visit the local library and look at several of the articlesin a chemistry journal such as The Journal of theAmerican Chemical Society. Write a brief summary ofyour observations regarding the format and style ofwriting in chemistry.

Cumulative ReviewRefresh your understanding of previous chapters byanswering the following.

79. What is chemistry? (Chapter 1)

80. What is mass? Weight? (Chapter 1)

81. Express the following in scientific notation. (Chapter 2)

a. 34 500 d. 789b. 2665 e. 75 600c. 0.9640 f. 0.002 189

82. Perform the following operations. (Chapter 2)

a. 107 � 103

b. (1.4 � 10�3) � (5.1 � 10�5)c. (2 � 10�3) � (4 � 105)

83. Convert 65°C to Kelvins. (Chapter 2)

84. Graph the following data. What is the slope of theline? (Chapter 2)

CHAPTER ASSESSMENT3

0 2 4 6 8

Mas

s o

f X

(g

)

40

30

20

10

Mass of Y (g)

II

III

I

IV

84

67. Mass percentageoxygen � 27.8%68. Mass percentagemercury � 93.0%

Law of Multiple Proportions (3.4)Level 2

69. The ratio of carbon to a fixed mass ofoxygen in compound I is 0.748:1, whilein compound II it is 0.375:1.

Mixed Review70. Gases are the most compressible state

of matter, solids the least.Compressibility is determined by theamount of space between particles ineach state. Gases have the greatestamount of space between particles,solids the least.

54. There are 91 naturallyoccurring elements. Thereare more than 20 syntheti-cally produced elements.

55. Mendeleev developed thefirst widely accepted peri-odic table of elements.

56. Yes, elements can be distin-guished from compounds.Compounds can be brokendown into their componentelements, whereas elementscannot be broken downinto simpler substances.

57. The properties of acompound are unique tothat compound anddifferent from those of itscomponent elements.

58. Elements within a group ofthe periodic table havesimilar chemical and phys-ical properties.

59. the law of definite pro-portions

Mastering ProblemsComplete solutions to ChapterAssessment problems can be foundin the Solutions Manual.

Properties of Matter (3.1)Level 1

60. Table 3-1 shows twocompounds that are whitesolids, but it is sucrose thatdecomposes before aboiling point is determined.Therefore the unknownsubstance is sucrose.

Conservation of Mass (3.2)Level 1

61. Massammonia � 34.0 g62. 68.0 g63. 47.0 g

Level 264. Masschlorine � 70.91 g65. Masscopper sulfide � 159 g

Law of Definite Proportions(3.4)Level 1

66. Mass percentageoxygen � 3%


85

Standardized Test Practice 85

Use these questions and the test-taking tip to preparefor your standardized test.

Interpreting Tables Use the table to answer questions 1 and 2.

1. What are the values for %Cl and %F, respectively, forSample II?

a. 0.622 and 61.65b. 61.65 and 38.35 c. 38.35 and 0.622 d. 38.35 and 61.65

2. Which of the following statements best describes therelationship between the two samples?

a. The compound in Sample I is the same as in SampleII. Therefore, the mass ratio of Cl to F in both samples will obey the law of definite proportions.

b. The compound in Sample I is the same as in SampleII. Therefore, the mass ratio of Cl to F in both samples will obey the law of multiple proportions.

c. The compound in Sample I is not the same as inSample II. Therefore, the mass ratio of Cl to F inboth samples will obey the law of proportions.

d. The compound in Sample I is not the same as inSample II. Therefore, the mass ratio of Cl to F in both samples will obey the law of multiple proportions.

3. After elements A and B react to completion in a closedcontainer, the ratio of masses of A and B in the con-tainer will be the same as before the reaction. This istrue because of the law of _____ .

a. definite proportionsb. multiple proportionsc. conservation of massd. conservation of energy

4. All of the following are physical properties of tablesugar (sucrose) EXCEPT _____ .

a. forms solid crystals at room temperatureb. appears as crystals white in colorc. breaks down into carbon and water vapor when heated d. tastes sweet

5. A substance is said to be in the solid state if _____ .

a. it is hard and rigidb. it can be compressed into a smaller volumec. it takes the shape of its containerd. its matter particles are close together

6. Na, K, Li, and Cs all share very similar chemicalproperties. In the periodic table of elements, they mostlikely belong to the same _____ .

a. row c. group b. period d. element

7. A heterogeneous mixture _______

a. cannot be separated by physical means.b. is composed of distinct areas of composition.c. is also called a solution.d. has the same composition throughout.

8. The percent by mass of sulfur in sulfuric acid, H2SO4,is _____ .

a. 32.69% c. 16.31%b. 64.13% d. 48.57%

9. Magnesium reacts explosively with oxygen to formmagnesium oxide. All of the following are true of thisreaction EXCEPT _______ .

a. The mass of magnesium oxide produced equals themass of magnesium consumed plus the mass ofoxygen consumed.

b. The reaction describes the formation of a newsubstance.

c. The product of the reaction, magnesium oxide, is achemical compound.

d. Magnesium oxide has physical and chemical properties similar to both oxygen and magnesium.

10. Which of the following is NOT a chemical reaction?

a. dissolution of sodium chloride in water b. combustion of gasolinec. fading of wallpaper by sunlightd. curdling of milk

STANDARDIZED TEST PRACTICECHAPTER 3

When Eliminating, Cross It Out Considereach answer choice individually and cross outchoices you’ve eliminated. If you can’t write in thetest booklet, use the scratch paper. List the answerchoice letters on the scratch paper and cross themout there. You’ll save time and stop yourself fromchoosing an answer you’ve mentally eliminated.

Mass Analysis of Two Chlorine–FluorineCompound Samples

Sample Mass chlorine Mass fluorine %Cl %F(g) (g)

I 13.022 6.978 65.11 34.89

II 5.753 9.248 ? ?

the amount of gravitational pullacting on the mass of an object. It ismeasured on a scale.

81. a. 3.45 � 104 d. 7.89 � 102

b. 2.665 � 103 e. 7.56 � 104

c. 9.640 � 10�1 f. 2.189 � 10�3

82. a. 1010

b. 7.1 � 10�8

c. 8 � 102

83. 338 K84. Slope � 33 kJ/g

Standardized Test Practice1. d 3. c 5. a 7. b 9. d2. d 4. c 6. c 8. a 10. a

71. a. homogeneousb. heterogeneousc. heterogeneousd. homogeneous

72. Masshydrogen � 6.0 gInitial masshydrogen � 316 g

73. Sample I:Masslead/Massoxygen � 6.46Sample II:Masslead/Massoxygen � 1.381The two samples are notthe same because the twoMasslead/Massoxygen ratiosare not the same.

Thinking Critically74. If the mixture of gases is

cooled sufficiently, it willcondense into a mixture ofliquids. This mixture couldthen be distilled.

75. a. Samples I, III, and IV are the same compound. A straight line can bedrawn through these threeplotted points. The slope ofthe line is equivalent toratio MassX/MassY. The factthat all three points are onthe same line shows thatthey all have the same massratio of X to Y and must bethe same compound.b. Mass ratio of X to Y forsamples I, II, and IV is 3.75:1.c. Sample II mass ratio is1.9:1

Cumulative Review79. Chemistry is the study of

matter and the changesthat it undergoes.

80. Mass is the measure of theamount of matter anobject contains. It ismeasured on a balance.The weight of an object is


Pages 84–852(C), 3(E), 4(A), 4(C), 4(D), 5(A),6(C)

Documents

CHAPTER 3 Matter—Properties and Changes - irion-isd.org · PDF file54 Chapter 3 What You’ll Learn You will distinguish between physical and chemical properties. You will classify