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A Glencoe ProgramHands-On Learning:Laboratory Manual, SE/TEForensics Laboratory Manual, SE/TECBL Laboratory Manual, SE/TESmall-Scale Laboratory Manual, SE/TEChemLab and MiniLab WorksheetsReview/Reinforcement:Study Guide for Content Mastery, SE/TESolving Problems: A Chemistry HandbookReviewing ChemistryGuided Reading Audio ProgramApplications and Enrichment:Challenge ProblemsSupplemental ProblemsTeacher Resources:Lesson PlansBlock Scheduling Lesson PlansSpanish ResourcesSection Focus Transparencies and MastersMath Skills Transparencies and MastersTeaching Transparencies and MastersSolutions ManualTechnology:Chemistry Interactive CD-ROMVocabulary PuzzleMaker Software,Windows/MacIntoshGlencoe Science Web site:science.glencoe.comAssessment:Chapter AssessmentMindJogger Videoquizzes (VHS/DVD)Computer Test Bank, Windows/MacIntoshCopyright by The McGraw-Hill Companies, Inc.All rights reserved. Permission is granted to reproduce the material contained hereinon the condition that such material be reproduced only for classroom use; be providedto students, teachers, and families without charge; and be used solely in conjunctionwith the Chemistry: Matter and Change program. Any other reproduction, for use orsale, is prohibited without prior written permission of the publisher.Send all inquiries to:Glencoe/McGraw-Hill8787 Orion PlaceColumbus, OH 43240-4027ISBN 0-07-824533-8Printed in the United States of America.1 2 3 4 5 6 7 8 9 10 045 09 08 07 06 05 04 03 02 01
CHALLENGE PROBLEMSContentsTo the Teacher . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ivChapter 1Production of Chlorofluorocarbons, 1950–1992 . . . . . . . . . 1Chapter 2Population Trends in the United States . . . . . . . . . . . . . . . . 2Chapter 3Physical and Chemical Changes . . . . . . . . . . . . . . . . . . . . . 3Chapter 4Isotopes of an Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Chapter 5Quantum Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Chapter 6Döbereiner’s Triads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Chapter 7Abundance of the Elements . . . . . . . . . . . . . . . . . . . . . . . . 7Chapter 8Comparing the Structures of Atoms and Ions . . . . . . . . . . . 8Chapter 9Exceptions to the Octet Rule . . . . . . . . . . . . . . . . . . . . . . . . 9Chapter 10 Balancing Chemical Equations . . . . . . . . . . . . . . . . . . . . . 10Chapter 11 Using Mole-Based Conversions . . . . . . . . . . . . . . . . . . . . 11Chapter 12 Mole Relationships in Chemical Reactions . . . . . . . . . . . . 12Chapter 13 Intermolecular Forces and Boiling Points . . . . . . . . . . . . . 13Copyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.Chapter 14 A Simple Mercury Barometer . . . . . . . . . . . . . . . . . . . . . . 14Chapter 15 Vapor Pressure Lowering . . . . . . . . . . . . . . . . . . . . . . . . . 15Chapter 16 Standard Heat of Formation . . . . . . . . . . . . . . . . . . . . . . . 16Chapter 17 Determining Reaction Rates . . . . . . . . . . . . . . . . . . . . . . . 17Chapter 18 Changing Equilibrium Concentrations in a Reaction . . . . . 18Chapter 19 Swimming Pool Chemistry . . . . . . . . . . . . . . . . . . . . . . . . 19Chapter 20 Balancing Oxidation–Reduction Equations . . . . . . . . . . . . 20Chapter 21 Effect of Concentration on Cell Potential . . . . . . . . . . . . . 21Chapter 22 Structural Isomers of Hexane . . . . . . . . . . . . . . . . . . . . . . 22Chapter 23 Boiling Points of Organic Families . . . . . . . . . . . . . . . . . . 23Chapter 24 The Chemistry of Life . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Chapter 25 The Production of Plutonium-239 . . . . . . . . . . . . . . . . . . . 25Chapter 26 The Phosphorus Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Answer Key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T27Challenge ProblemsChemistry: Matter and Changeiii
To the TeacherCopyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.Students can take their learning one step beyond their textbooks withChallenge Problems. The worksheets in this supplement to Chemistry:Matter and Change challenge students to apply their knowledge ofchemistry to new situations, analyze and interpret those situations, andsynthesize responses. Whether analyzing experimental results or investigatinga hypothetical situation, these worksheets encourage students to use chemicalconcepts along with their critical thinking skills to solve problems.ivChemistry: Matter and ChangeChallenge Problems
NameCHAPTERDate1ClassCHALLENGE PROBLEMSChlorofluorocarbons (CFCs) were first produced inthe laboratory in the late 1920s. They did notbecome an important commercial product until sometime later. Eventually, CFCs grew in popularity untiltheir effect on the ozone layer was discovered in the1970s. The graph shows the combined amounts of twoimportant CFCs produced between 1950 and 1992.Answer the following questions about the graph.Amount of CFCs(billion kilograms)Production ofChlorofluorocarbons, 1950–199240035030025020015010050019501960Use with Chapter 1,Section 1.11970Year198019901. What was the approximate amount of CFCs produced in 1950? In 1960? In 1970?2. In what year was the largest amount of CFCs produced? About how much was producedthat year?Copyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.3. During what two-year period did the production of CFCs decrease by the greatestamount? By about how much did their production decrease?4. During what two-year period did the production of CFCs increase by the greatestamount? What was the approximate percent increase during this period?5. How confident would you feel about predicting the production levels of CFCs during theodd numbered years 1961, 1971, and 1981? Explain.6. Could the data in the graph be presented in the form of a circle graph? Explain.Challenge ProblemsChemistry: Matter and Change Chapter 11
NameDateCHAPTER2ClassCHALLENGE PROBLEMSPopulation Trends in theUnited StatesUse with Chapter 2,Section 2.4The population of the United States is becoming more diverse. The circle graphs below show thedistribution of the U.S. population among five ethnic groups in 1990 and 2000. The estimatedtotal U.S. population for those two years was 2.488 108 in 1990 and 2.754 108 in 2000.U.S. Population DistributionAfrican American11.8%Hispanic American9.0%Asian American2.8%Native American0.70%19902000African American12.2%Hispanic American11.8%Caucasian75.7%Asian American3.8%Native American0.70%Caucasian71.4%(Percentages may not add up to 100% due to rounding.)1. By how much did the total U.S. population increase between 1990 and 2000? What was2. Calculate the total population for each of the five groups for 1990 and 2000.3. Make a bar graph that compares the population for the five groups in 1990 and 2000. Inwhat ways is the bar graph better than the circle graphs? In what way is it less useful?2Chemistry: Matter and Change Chapter 2Challenge ProblemsCopyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.the percent increase during this period?
NameCHAPTERDate3ClassCHALLENGE PROBLEMSPhysical and ChemicalChangesUse with Chapter 3,Section 3.2Physical and chemical changes occur all around us. One of the many places in whichphysical and chemical changes occur is the kitchen. For example, cooking spaghetti in apot of water on the stove involves such changes. For each of the changes described below, tell(a) whether the change that occurs is physical or chemical, and (b) how you made your choicebetween these two possibilities. If you are unable to decide whether the change is physical orchemical, tell what additional information you would need in order to make a decision.1. As the water in the pot is heated, its temperature rises.2. As more heat is added, the water begins to boil and steam is produced.Copyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.3. The heat used to cook is produced by burning natural gas in the stove burner.4. The metal burner on which the pot rests while being heated becomes red as itstemperature rises.5. After the flame has been turned off, a small area on the burner has changed in color fromblack to gray.6. A strand of spaghetti has fallen onto the burner, where it turns black and begins tosmoke.7. When the spaghetti is cooked in the boiling water, it becomes soft.Challenge ProblemsChemistry: Matter and Change Chapter 33
NameDateCHAPTER4ClassCHALLENGE PROBLEMSIsotopes of an Elementmass spectrometer is a device for separatingatoms and molecules according to theirmass. A substance is first heated in a vacuum andthen ionized. The ions produced are acceleratedthrough a magnetic field that separates ions of different masses. The graph below was producedwhen a certain element (element X) was analyzedin a mass spectrometer. Use the graph to answerthe questions below.30Percent abundanceAUse with Chapter 4,Section 4.32520151050190 192 194 196 198 200 202 204 206 208 210Atomic mass (amu)1. How many isotopes of element X exist?2. What is the mass of the most abundant isotope?3. What is the mass of the least abundant isotope?4. What is the mass of the heaviest isotope?5. What is the mass of the lightest isotope?Copyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.6. Estimate the percent abundance of each isotope shown on the graph.7. Without performing any calculations, predict the approximate atomic mass for elementX. Explain the basis for your prediction.8. Using the data given by the graph, calculate the weighted average atomic mass ofelement X. Identify the unknown element.4Chemistry: Matter and Change Chapter 4Challenge Problems
NameDate5CHAPTERClassCHALLENGE PROBLEMSQuantum NumbersUse with Chapter 5,Section 5.2The state of an electron in an atom can be completely described by four quantum numbers,designated as n, , m , and ms. The first, or principal, quantum number, n, indicates theelectron’s approximate distance from the nucleus. The second quantum number, , describesthe shape of the electron’s orbit around the nucleus. The third quantum number, m , describesthe orientation of the electron’s orbit compared to the plane of the atom. The fourth quantumnumber, ms, tells the direction of the electron’s spin (clockwise or counterclockwise).The Schrödinger wave equation imposes certain mathematical restrictions on the quantumnumbers. They are as follows:n can be any integer (whole number),Copyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. can be any integer from 0 to n 1,m can be any integer from to , and1 or 1ms can be 22As an example, consider electrons in the first energy level of an atom, that is, n 1. Inthis case, can have any integral value from 0 to (n 1), or 0 to (1 1). In other words, must be 0 for these electrons. Also, the only value that m can have is 0. The electrons in1 or 1 for m . These restrictions agree with thethis energy level can have values of s22observation that the first energy level can have only two electrons. Their quantum numbers1 and 1, 0, 0 1 .are 1, 0, 0, 22Use the rules given above to complete the table listing the quantum numbers for eachelectron in a boron atom. The correct quantum numbers for one electron in the atom isprovided as an example.Boron (B)Electronn m ms11001 22345Challenge ProblemsChemistry: Matter and Change Chapter 55
NameDateCHAPTER6ClassCHALLENGE PROBLEMSDöbereiner’s TriadsUse with Chapter 6,Section 6.2One of the first somewhat successful attempts to arrange the elements in a systematic waywas made by the German chemist Johann Wolfgang Döbereiner (1780–1849). In 1816,Döbereiner noticed that the then accepted atomic mass of strontium (50) was midway betweenthe atomic masses of calcium (27.5) and barium (72.5). Note that the accepted atomic massesfor these elements today are very different from their accepted atomic masses at the timeDöbereiner made his observations. Döbereiner also observed that strontium, calcium, and barium showed a gradual gradation in their properties, with the values of some of strontium’sproperties being about midway between the values of calcium and barium. Döbereiner eventually found four other sets of three elements, which he called triads, that followed the same pattern. In each triad, the atomic mass of the middle element was about midway between theatomic masses of the other two elements. Unfortunately, because Döbereiner’s system did notturn out to be very useful, it was largely ignored.Set 1ElementMelting Point ( C) 219.6FluorineChlorineSet 2Calculated:ElementActual:Boiling Point ( C)Krypton ry: Matter and Change Chapter 6Calculated:Strontium1384Set 6Melting Point ( C)937Calculated:ElementBoiling Point ( C)BerylliumMagnesiumActual: 621107Actual:39.098GermaniumBoiling Point ( C)MagnesiumSet 5ElementRadonCalculated:PotassiumSet 4Xenon6.941ElementActual: 7.2BromineAtomic MassLithiumSodiumSet 31285Calculated:Actual:327Calcium851Challenge ProblemsCopyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.Had Döbereiner actually discovered a way of identifying trends among the elements?Listed below are six three-element groups in which the elements in each group are consecutivemembers of the same group in the periodic table. The elements in each set show a gradation intheir properties. Values for the first and third element in each set are given. Determine the missing value in each set by calculating the average of the two given values. Then, compare the values you obtained with those given in the Handbook of Chemistry and Physics. Record theactual values below your calculated values. Is the value of the property of the middle elementin each set midway between the values of the other two elements in the set?
NameCHAPTERDate7ClassCHALLENGE PROBLEMSAbundance of the ElementsUse with Chapter 7,Section 7.1The abundance of the elements differs significantly in various parts of theuniverse. The table below lists the abundance of some elements in variousparts of the universe. Use the table to answer the following questions.Abundance (Number of atoms per 1000 atoms)*ElementUniverseHydrogen927Helium71.8Solar SystemEarth863Earth’s CrustHuman 210Iron0.01390.0032017019* An element is not abundant in a region that is left blank.1. What percent of all atoms in the universe are either hydrogen or helium? What percent ofCopyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.all atoms in the solar system are either hydrogen or helium?2. Explain the relatively high abundance of hydrogen and helium in the universe comparedto their relatively low abundance on Earth.3. Only the top four most abundant elements on Earth and in Earth’s crust are shown in thetable. Name two additional elements you would expect to find among the top ten elements both on Earth and in Earth’s crust. Explain your choices.4. Name at least three elements in addition to those shown in the table that you wouldexpect to find in the list of the top ten elements in the human body. Explain your choices.Challenge ProblemsChemistry: Matter and Change Chapter 77
NameDateCHAPTER8ClassCHALLENGE PROBLEMSComparing the Structures ofAtoms and IonsUse with Chapter 8,Section 8.1The chemical properties of an element depend primarily on its number of valence electrons inits atoms. The noble gas elements, for example, all have similar chemical propertiesbecause the outermost energy levels of their atoms are completely filled. The chemical propertiesof ions also depend on the number of valence electrons. Any ion with a complete outermostenergy level will have chemical properties similar to those of the noble gas elements. The fluoride ion (F ), for example, has a total of ten electrons, eight of which fill its outermost energylevel. F has chemical properties, therefore, similar to those of the noble gas neon.Shown below are the Lewis electron dot structures for five elements: sulfur (S), chlorine (Cl),argon (Ar), potassium (K), and calcium (Ca). Answer the questions below about these structures.SClArKCa1. Write the atomic number for each of the five elements shown above.Copyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.2. Write the electron configuration for each of the five elements.3. Which of the above Lewis electron dot structures is the same as the Lewis electron dotstructure for the ion S2 ? Explain your answer.4. Which of the above Lewis electron dot structures is the same as that for the ion Cl ?Explain your answer.5. Which of the above Lewis electron dot structures is like that for the ion K ? Explainyour answer.6. Name an ion of calcium that has chemical properties similar to those of argon. Explainyour answer.8Chemistry: Matter and Change Chapter 8Challenge Problems
NameCHAPTERDate9ClassCHALLENGE PROBLEMSExceptions to the Octet RuleUse with Chapter 9,Section 9.3The octet rule is an important guide to understanding how most compounds are formed.However, there are a number of cases in which the octet rule does not apply. Answer thefollowing questions about exceptions to the octet rule.1. Draw the Lewis structure for the compound BeF2.2. Does BeF2 obey the octet rule? Explain.3. Draw the Lewis structure for the compound NO2.Copyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.4. Does NO2 obey the octet rule? Explain.5. Draw the Lewis structure for the compound N2F2.6. Does N2F2 obey the octet rule? Explain.7. Draw the Lewis structure for the compound IF5.8. Does IF5 obey the octet rule? Explain.Challenge ProblemsChemistry: Matter and Change Chapter 99
NameDateCHAPTER10ClassCHALLENGE PROBLEMSBalancing ChemicalEquationsUse with Chapter 10,Section 10.1Each chemical equation below contains at least one error. Identify the error or errors andthen write the correct chemical equation for the reaction.1. K(s) 2H2O(l) 0 2KOH(aq) H2(g)2. MgCl2(aq) H2SO4(aq) 0 Mg(SO4)2(aq) 2HCl(aq)3. AgNO3(aq) H2S(aq) 0 Ag2S(aq) HNO3(aq)Copyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.4. Sr(s) F2(g) 0 Sr2F5. 2NaHCO3(s) 2HCl(aq) 0 2NaCl(s) 2CO2(g)6. 2LiOH(aq) 2HBr(aq) 0 2LiBr(aq) 2H2O7. NH4OH(aq) KOH(aq) 0 KOH(aq) NH4OH(aq)8. 2Ca(s) Cl2(g) 0 2CaCl(aq)9. H2SO4(aq) 2Al(NO3)3(aq) 0 Al2(SO4)3(aq) 2HNO3(aq)10Chemistry: Matter and Change Chapter 10Challenge Problems
NameDate11CHAPTERClassCHALLENGE PROBLEMSUsing Mole-BasedConversionsUse with Chapter 11,Section 11.3The diagram shows three containers, each of which holds a certain mass of thesubstance indicated. Complete the table below for each of the three substances.UF6 (g)CCl3CF3 (l)Pb (s)225.0 g200.0 g250.0 gSubstanceMass (g)Molar Mass(g/mol)Number ofMoles (mol)Number of RepresentativeParticlesUF6(g)CCl3CF3(l)Copyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.Pb(s)1. Compare and contrast the number of representative particles and the mass of UF6 withthe number of representative particles and mass of CCl3CF3. Explain any differencesyou observe.2. UF6 is a gas used in the production of fuel for nuclear power plants. How many moles ofthe gas are in 100.0 g of UF6?3. CCl3CF3 is a chlorofluorocarbon responsible for the destruction of the ozone layer inEarth’s atmosphere. How many molecules of the liquid are in 1.0 g of CCl3CF3?4. Lead (Pb) is used to make a number of different alloys. What is the mass of lead presentin an alloy containing 0.15 mol of lead?Challenge ProblemsChemistry: Matter and Change Chapter 1111
NameDateCHAPTER12ClassCHALLENGE PROBLEMSMole Relationships inChemical ReactionsUse with Chapter 12,Section 12.2The mole provides a convenient way of finding the amounts of the substances in a chemicalreaction. The diagram below shows how this concept can be applied to the reactionbetween carbon monoxide (CO) and oxygen (O2), shown in the following balanced equation.2CO(g) O2(g) 0 2CO2(g)Use the equation and the diagram to answer the following questions.Moles ofCO3Particles ofCO1624Grams ofCOMoles ofCO257Particles ofCO2Grams ofCO21. What information is needed to make the types of conversions shown by double-arrow 1in the diagram?Copyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.2. What conversion factors would be needed to make the conversions represented bydouble-arrow 2 in the diagram for CO? By double-arrow 6 for CO2?3. What information is needed to make the types of conversions represented bydouble-arrows 3 and 7 in the diagram?4. What conversion factors would be needed to make the conversions represented bydouble-arrow 3 in the diagram for CO?5. Why is it not possible to convert between the mass of a substance and the number ofrepresentative particles, as represented by double-arrow 4 of the diagram?6. Why is it not possible to use the mass of one substance in a chemical reaction to find the massof a second substance in the reaction, as represented by double-arrow 5 in the diagram?12Chemistry: Matter and Change Chapter 12Challenge Problems
NameCHAPTERDate13ClassCHALLENGE PROBLEMSIntermolecular Forces andBoiling Pointshe boiling points of liquids depend partly on the mass of theparticles of which they are made. The greater the mass ofthe particles, the more energy is needed to convert a liquid to agas, and, thus, the higher the boiling point of the liquid. This pattern may not hold true, however, when there are significant forcesbetween the particles of a liquid. The graph plots boiling pointversus molecular mass for group 4A and group 6A hydrides. Ahydride is a binary compound containing hydrogen and one otherelement. Use the graph to answer the following questions.100Boiling point ( C)TUse with Chapter 13,Section 13.3H2OH2Te0H2SeH2S 10000Group 6AhydridesSiH4CH4SnH4GeH4Group 4Ahydrides50100Molecular mass1501. How do the boiling points of the group 4A hydrides change as the molecular masses ofthe hydrides change?Copyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.2. What are the molecular structure and polarity of the four group 4A hydrides?3. Predict the strength of the forces between group 4A hydride molecules. Explain howthose forces affect the boiling points of group 4A hydrides.4. How do the boiling points of the group 6A hydrides change as the molecular masses ofthe hydrides change?5. What are the molecular structure and polarity of the four group 6A hydrides?6. Use Table 9-4 in your textbook to determine the difference in electronegativities of thebonds in the four group 6A hydrides.Challenge ProblemsChemistry: Matter and Change Chapter 1313
NameDateCHAPTER14ClassCHALLENGE PROBLEMSA Simple Mercury BarometerIn Figure 1, a simple mercury barometer is made by filling a longglass tube with mercury and then inverting the open end of thetube into a bowl of mercury. Answer the following questions aboutthe simple mercury barometer shown here.Use with Chapter 14,Section 14.1Glass tubeMercurycolumn1. What occupies the space above the mercury column in theBowl ofmercurybarometer’s glass tube?At sea levelAt 500 metersabove sea levelFigure 1Figure 22. What prevents mercury from flowing out of the glass tube into the bowl of mercury?3. When the barometer in Figure 1 is moved to a higher elevation, such as an altitude of4. Suppose the barometer in Figure 1 was carried into an open mine 500 meters below sealevel. How would the height of the mercury column change? Explain why.5. Suppose the liquid used to make the barometer was water instead of mercury. How wouldthis substitution affect the barometer? Explain.6. Suppose a tiny crack formed at the top of the barometer’s glass tube. How would thisevent affect the column of mercury? Explain why.14Chemistry: Matter and Change Chapter 14Challenge ProblemsCopyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.5000 meters, the column of mercury changes as shown in Figure 2. Why is the mercurycolumn lower in Figure 2 than in Figure 1?
NameCHAPTERDate15ClassCHALLENGE PROBLEMSVapor Pressure LoweringUse with Chapter 15,Section 15.3You have learned that adding a nonvolatile solute to a solventlowers the vapor pressure of that solvent. The amount bywhich the vapor pressure is lowered can be calculated by means ofa relationship discovered by the French chemist François MarieRaoult (1830–1901) in 1886. According to Raoult’s law, the vaporpressure of a solvent (P) is equal to the product of its vapor pressurewhen pure (P0) and its mole fraction (X) in the solution, orP P0XThe solution shown at the right was made by adding 75.0 g ofsucrose (C12H22O11) to 500.0 g of water at a temperature of 20 C.Answer the following questions about this ight Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.1. Why do the sugar molecules in the solution lower the vapor pressure of the water?2. What is the number of moles of sucrose in the solution?3. What is the number of moles of water in the solution?4. What is the mole fraction of water in the solution?5. What is the vapor pressure of the solution if the vapor pressure of pure water at 20 C is17.54 mm Hg?6. How much is the vapor pressure of the solution reduced from that of water by theaddition of the sucrose?Challenge ProblemsChemistry: Matter and Change Chapter 1515
NameDateCHAPTER16ClassCHALLENGE PROBLEMSStandard Heat of FormationC(s) O2(g)H H 110 kJ/molCO(g) 1O (g)2 2 H 393 kJ/molEnthalpyess’s law allows you to determine thestandard heat of formation of a compoundwhen you know the heats of reactions that leadto the production of that compound. The firstdiagram on the right shows how Hess’s law canbe used to calculate the heat of formation ofCO2 by knowing the heats of reaction of twosteps leading to the production of CO2. Use thisdiagram to help you answer the questions belowabout the second diagram.Use with Chapter 16,Section 16.4 H 283 kJ/molThe equations below show how NO2 can beformed in two ways: directly from the elementsor in two steps. H 33 kJ/mol11 N2(g) O2(g) 0 NO(g)22 H 91 kJ/mol1 O (g) 0 NO (g)NO(g) 22 2 H 58 kJ/molCO2(g)CNO(g) 1/2 O2(g)1. On the diagram at the right, draw arrowheadsto show the directions in which the three lineslabeled 1, 2, and 3 should point.2. Write the correct reactants and/or products on2 H 58 kJ/moleach of the lines labeled A, B, and C.1 H 91 kJ/moleach number on the diagram.Enthalpy3. Write the correct enthalpy change next toBNO2(g)3 H 33 kJ/molA16Chemistry: Matter and Change Chapter 161/2 N2(g) O2(g)Challenge ProblemsCopyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.1 N2(g) O2(g) 0 NO2(g)2or
NameDateCHAPTER17ClassCHALLENGE PROBLEMSDetermining Reaction Ratesinitrogen pentoxide decomposes to producenitrogen dioxide and oxygen as representedby the following equation.2N2O5(g) 0 4NO2(g) O2(g)The graph on the right represents the concentration of N2O5 remaining as the reaction proceedsover time. Answer the following questions aboutthe reaction.1.6Concentration (mol/L)DUse with Chapter 17,Section 17.11.41.21.00.80.60.40.200 1 2 3 4 5 6 7 8 9 10Time (h)1. What is the concentration of N2O5 at the beginning of the experiment? After 1 hour?After 2 hours? After 10 hours?2. By how much does the concentration of N2O5 change during the first hour of theCopyright Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.reaction? Calculate the percentage of change the concentration undergoes during thefirst hour of the reaction.3. The instantaneous rate of reaction is defined as the change in concentration of reactantduring some specified time period, or instantaneous rate of reaction [N2O5]/t. What isthe instantaneous rate of reaction for the decomposition of N2O5 for the time periodbetween the first and second hours of the reaction? Between the second and third hours?Between the sixth and seventh hours?4. What is the instantaneous rate of reaction for the decomposition of N2O5 between the sec-ond and fourth hours of the reaction? Between the third and eighth hours of the reaction?5. How long does it take for 0.10 mol of N2O5 to decompose during the tenth hour of the reaction?6. What is the average rate of reaction for the decomposition of N2O5 overall?Challenge ProblemsChemistry: Matter and Change Chapter 1717
NameDateCHAPTER18ClassCHALLENGE PROBLEMSReversible reactions eventually reach an equilibriumcondition in which the concentrations of all reactantsand products are constant. Equilibrium can be disturbed,however, by the addition or removal of either a reactant orproduct. The graph on the right shows how the concentrations of the reactants and product of a reaction changewhen equilibrium is disturbed. Use the graph to answer thefollowing questions.Concentration (mol/L)Changing EquilibriumConcentrations in a Reaction876543210Use with Chapter 18,Section 18.1SO2SO2O2O2SO3SO30 1 2 3 4 5 6 7 8 9 10Time (sec)1. Write the equation for the reaction depicted in the graph.2. Write the equilibrium constant expression for the reaction.3. Explain the shapes of the curves for the three gases during the first 2 minutes of the4. At approximately what time does the reaction reach equilibrium? How do you knowequilibrium has been reached?5. What are the concentrations of the three gases at equilibrium?6. Calculate the value of Keq for the reaction.7. Describe the change made in the system 4 minutes into the reaction. Tell how you knowthe change was made.8. At what time does the system return to equilibrium?18Chemistry: Matter and Change C
Challenge Problems Chemistry: Matter and Change Chapter 3 3 Physical and Chemical Changes Physical and Chemical Changes Physical and chemical changes occur all around us. One of the many places in which physical and chemical changes occur is the kitchen. For example, cooking spaghe
