724 724 BIG Idea Most compounds containing the element carbon are organic compounds. 24. 1 Simple Organic Compounds Hydrocarbons are compounds made only of car- bon and hydrogen atoms. 24.2 Other Organic Compounds Substituted hydro- carbons contain other elements besides carbon and hydrogen. 24.3 Petroleum—A Source of Carbon Compounds Petroleum is the source of carbon compounds used to make plastics, fossil fuels, and many other products. 24.4 Biological Compounds Proteins, nucleic acids, carbohydrates, and lipids are polymers made by plants and animals. MAIN Idea MAIN Idea MAIN Idea MAIN Idea What’s in the willows? The bark of willow trees has been used to treat pain and fever. Willow bark contains a com- pound related to aspirin. Today, aspirin and thou- sands of other useful sub- stances are synthesized from compounds found in petroleum. List other medicines from natural sources, such as plants. Science Journal Walter Bibikow/Index Stock Imagery
Transcript
724724
BIG Idea Most compounds containing theelement carbon are organiccompounds.
24. 1 Simple OrganicCompounds
Hydrocarbons arecompounds made only of car-bon and hydrogen atoms.
24.2 Other OrganicCompounds
Substituted hydro-carbons contain other elementsbesides carbon and hydrogen.
24.3 Petroleum—A Sourceof Carbon Compounds
Petroleum is thesource of carbon compoundsused to make plastics, fossilfuels, and many other products.
24.4 Biological CompoundsProteins, nucleic
acids, carbohydrates, and lipidsare polymers made by plantsand animals.
MAIN Idea
MAIN Idea
MAIN Idea
MAIN Idea
What’s in the willows?The bark of willow treeshas been used to treatpain and fever. Willowbark contains a com-pound related to aspirin.Today, aspirin and thou-sands of other useful sub-stances are synthesizedfrom compounds foundin petroleum.
List other medicines fromnatural sources, such asplants.
Science Journal
Walter Bibikow/Index Stock Imagery
Start-Up Activities
Organic Compounds Make thefollowing Foldable to help youunderstand the vocabularyterms in this chapter.
Fold a vertical sheetof notebook paperfrom side to side.
Cut along every third line of only thetop layer to form tabs.
Build Vocabulary As you read the chapter, listthe vocabulary words about organic compoundson the tabs. As you learn the definitions, writethem under the tab for each vocabulary word.
STEP 2
STEP 1
Carbon, the Organic ElementThe element carbon exists in three very differ-ent forms: dull, black charcoal; slippery, graygraphite; and bright, sparkling diamond.However, this is nothing compared with themillions of different compounds that carboncan form. In this lab, you will seek out thecarbon hidden in two common substances.
WARNING: Always use extreme cautionaround an open flame. Point test tubes awayfrom yourself and others.
1. Place a small piece of bread in a test tube.
2. Using a test-tube holder, hold the tubeover the flame of a laboratory burner untilyou observe changes in the bread.
3. Using a clean test tube and a smallamount of paper instead of bread,repeat step 2.
4. Think Critically Based on what youobserved and what remained in the testtubes, infer what these residues might be.
Preview this chapter’s contentand activities at gpscience.com
Organic Compounds What do you have in common with your athletic shoes, sun-
glasses, and backpack? All the items shown in Figure 1 containcompounds of the element carbon—and so do you. Most com-pounds containing the element carbon are organic compounds.
At one time, scientists thought that only living organismscould make organic compounds, which is how they got theirname. By 1830, scientists could make organic compounds inlaboratories, but they continued to call them organic.
Of the millions of carbon compounds known today, more than90 percent of them are considered organic. The others, includingcarbon dioxide and the carbonates, are considered inorganic.
Bonding You may wonder why carbon can form so many organiccompounds. The main reason is that a carbon atom has four elec-trons in its outer energy level. This means that each carbon atomcan form four covalent bonds with atoms of carbon or with otherelements. As you have learned, a covalent bond is formed when twoatoms share a pair of electrons. This large number of bonds allowscarbon to form many types of compounds ranging from smallcompounds used as fuel, to complex compounds found in medi-cines and dyes, and the polymers used in plastics and textile fibers.
Simple OrganicCompounds
Figure 1 Most items used everyday contain carbon.
Reading Guide
■ Identify the difference betweenorganic and inorganic carboncompounds.
■ Examine the structures of someorganic compounds.
■ Differentiate between saturatedand unsaturated hydrocarbons.
■ Identify isomers of organiccompounds.
Carbon compounds surround you—they’re in your food, your body, andmost materials you use every day.
Review Vocabularycompound: substance formed fromtwo or more elements
New Vocabulary
• organic compound
• hydrocarbon
• saturated hydrocarbon
• isomer
• unsaturated hydrocarbon
KS Studios
SECTION 1 Simple Organic Compounds 727
Arrangement Another reason carbon can form so manycompounds is that carbon can link together with other carbonatoms in many different arrangements—chains, branchedchains, and even rings. It also can form double and triple bondsas well as single bonds. In addition, carbon can bond with atomsof many other elements, such as hydrogen and oxygen. Figure 2shows some possible arrangements for carbon compounds.
Hydrocarbons Carbon forms an enormous number of compounds with
hydrogen alone. A compound made up of only carbon andhydrogen atoms is called a hydrocarbon. Does the furnace,stove, or water heater in your home burn natural gas? A maincomponent of the natural gas used for these purposes is the hy-drocarbon methane. The chemical formula of methane is CH4.
Methane can be represented in two other ways, as shown inFigure 3. The structural formula uses lines to show that fourhydrogen atoms are bonded to one carbon atom in a methanemolecule. Each line between atoms represents a single covalentbond. The second way, the space-filling model, shows a morerealistic picture of the relative size and arrangement of theatoms in the molecule. Most often, however, chemists use chem-ical and structural formulas to write about reactions.
Name three ways that chemists representorganic compounds.
Another hydrocarbon used as fuel is propane. Some stoves,most outdoor grills, and the heaters in hot-air balloons burn thishydrocarbon, which is found in bottled gas. Propane’s structuralformula and space-filling model also are shown in Figure 3.
Methane and other hydrocarbons produce more than90 percent of the energy humans use. Carbon compounds alsoare important in medicines, foods, and clothing. To understandhow carbon can play so many roles, you must understand howit forms bonds.
Figure 2 Carbon atoms bond toform straight, branched, and cyclicchains.
MethaneCH4
H — C — H
H
H
——
PropaneC3H8
H — C — C — C — H
H
H
——
H
H
——
H
H
——
H — C — C — C — C — C — C — C — H
H
——
H
——
H
H
——
H
——
HH
H
——
HH H
H
——
H
H
——
H
H
—
H
C C — C C
H
H
—— ——
H — C — H
H
—
H O
OH
O — C — H
H
—
H
—
H
H H
C
C
C
C
C
C
C
——
——
——
—
——
— —
H
H — C — H
——
H
Figure 3 Natural gas is mostlymethane, CH4, but bottled gas ismostly propane, C3H8.Compare and contrast the twogases.
Heptane is found in gasoline.
Isoprene exists in natural rubber.
Vanillin is found in vanilla flavoring.
728 CHAPTER 24 Organic Compounds
Single Bonds In some hydrocarbons, the carbon atoms are
joined by single covalent bonds. Hydrocarbonscontaining only single-bonded carbon atoms arecalled saturated hydrocarbons. Saturated meansthat a compound holds as many hydrogen atomsas possible—it is saturated with hydrogen atoms.
What are saturatedhydrocarbons?
Table 1 lists four saturated hydrocarbons.Notice how each carbon atom appears to be alink in a chain connected by single covalentbonds. Figure 4 shows a graph of the boilingpoints of some hydrocarbons. Notice the rela-tionship between boiling points and the addi-tion of carbon atoms.
Structural Isomers Perhaps you have seenor know about butane, which is a gas that some-
times is burned in camping stoves and lighters. The chemicalformula of butane is C4H10. Another hydrocarbon called isobu-tane has exactly the same chemical formula. How can this be?The answer lies in the arrangement of the four carbon atoms.Look at Figure 5. In a molecule of butane, the carbon atomsform a continuous chain. The carbon chain of isobutane isbranched. The arrangement of carbon atoms in each compoundchanges the shape of the molecule, and very often affects itsphysical properties, as you will soon see. Isobutane and butaneare isomers.
Figure 4 Boiling points ofhydrocarbons increase as thenumber of carbon atoms in thechain increases.Predict the approximate boilingpoint of hexane.
Table 1 Some Hydrocarbons
Na tructuralFormula
Me
Eth
Pro
Bu
H | H—C—H | H
H | H—C— | H
H | C—H | H
H | H—C— | H
H | C— | H
H | C—H | H
H | H—C— | H
H | C— | H
H | C— | H
H | C—H | H
Boiling Points of Hydrocarbons
–100
–50
–150
–200
0
50
Number of carbon atoms in chain
Boi
ling
poi
nt
(�C)
0 1 2 3 4 5 6
Methane
Ethane
PropaneButane
Pentane
SECTION 1 Simple Organic Compounds 729
Isomers are compounds that have identical chemical formu-las but different molecular structures and shapes. Thousands ofisomers exist among the hydrocarbons. Generally, meltingpoints and boiling points are lowered as the amount of branch-ing in an isomer increases. You can see this pattern in Table 2,which lists properties of butane and isobutane.
Sometimes properties of isomers can vary amazingly. Forexample, the isomer of octane having all eight carbons in astraight chain melts at �56.8°C, but the most branched octanemelts at 100.7°C. In this case, the high melting point resultsfrom the symmetry of the molecule and its globular shape. Lookfor this isomer when you do the Try at Home MiniLAB.
Other Isomers There are many other kinds of isomers inorganic and inorganic chemistry. Some isomers differ onlyslightly in how their atoms are arranged in space. Such isomersform what often are called right- and left-handed molecules, likemirror images. Two such isomers may have nearly identicalphysical and chemical properties.
ButaneC4H10
H — C — C — C — C — H
H
H
——
H
H
——
H
H—
—
H
H
—— Isobutane
C4H10
H — C — C — C — H
H — C — H
H
——
——
H
H
——
H
—
H
H
——
Table 2 Properties of Butane Isomers
Property Butane Isobutane
Description Colorless gas Colorless gas
Density 0.60 kg/L 0.603 kg/L
Melting point �135°C �145°C
Boiling point �0.5°C �10.2°C
Modeling Structuresof OctaneProcedure1. To model octane, C8H18,
a hydrocarbon found ingasoline, use soft gum-drops to represent carbonatoms.
2. Use raisins to representhydrogen atoms.
3. Use toothpicks for chemi-cal bonds. WARNING: NEVER eat anyfood in the laboratory.
Analysis1. How do you distinguish
one structure fromanother?
2. What was the total num-ber of different moleculesfound in yourclass?
Figure 5 Butane has two iso-mers, one with a straight chainand the other isomer with abranched chain.
730 CHAPTER 24 Organic Compounds
Self Check1. Explain how organic compounds got this name.
2. Compare and contrast ethane, ethene, and ethyne.
3. Explain the term saturated in relation to hydrocarbons.With what are such compounds saturated?
4. Describe how boiling and melting points generally varyas branching in a hydrocarbon chain increases.
5. Think Critically Cyclopropane is a cyclic, saturated hydro-carbon containing three carbon atoms. Draw its structuralformula. Are cyclopropane and propane isomers? Explain.
SummaryOrganic Compounds
• Most compounds containing the elementcarbon are organic compounds.
• Carbon can form many compounds because ithas four electrons in its outer energy level.
• Carbon can bond with atoms of other elements,such as hydrogen, oxygen, and nitrogen.
Hydrocarbons
• A compound containing only carbon andhydrogen atoms is a hydrocarbon.
• Saturated hydrocarbons contain only singlebonds.
Isomers and Multiple Bonds
• Compounds that have identical chemical for-mulas but different molecular structures arecalled isomers.
6. Ratios The formula for the saturated hydrocarbonoctane is C8 H18. Adding one double bond makes thehydrocarbon octene, having the formula C8 H16. Writethe formulas of the hydrocarbons formed by addingone, two, and three more double bonds to octene.Find the ratio of hydrogen decrease to the number of double bonds?
Multiple Bonds Peaches are among the many fruits that can form
small quantities of ethylene gas, which aids in ripen-ing. Ethylene is another name for the hydrocarbonethene, C2H4. This contains one double bond in whichtwo carbon atoms share two pairs of electrons. Thehydrocarbon ethyne contains a triple bond in whichthree pairs of electrons are shared. Hydrocarbons, suchas ethene and ethyne, that contain at least one doubleor triple bond are called unsaturated hydrocarbons.They are shown in Figure 6.
What is another name for ethene?
An easy way to remember what type ofbond a hydrocarbon has is to look at the lastthree letters. Compounds ending with –anehave a single bond; the ending –ene indi-cates a double bond, and –yne indicates atriple bond.
Figure 6 Hydrocarbonscan contain double or triplebonds between carbon atoms.Ethyne, also called acetylene,is used in torches for welding.Ethene or ethylene gas ripens fruit.
■ Define aromatic compounds.■ Identify the nature of alcohols
and acids.■ Identify organic compounds you
use in daily life.
Aromatic compounds are buildingblocks of thousands of usefulcompounds, such as flavoringsand medicines.
Review Vocabularystructural formula: a molecularmodel that uses symbols and bondsto show relative positions of atoms
New Vocabulary
• aromatic compound
• substituted hydrocarbon
• alcohol
Aromatic Compounds Chewing flavored gum or dissolving a candy mint in your
mouth releases pleasant flavors and aromas. Many chemicalcompounds produce pleasant odors but others have lesspleasant flavors and smells. For example, aspirin, which hasan unpleasant, sour taste, and methyl salicylate, the com-pound that produces the fresh fragrance of wintergreen,shown in Figure 7. Both of these compounds are consideredaromatic compounds. In addition to the fragrances men-tioned here, aromatic compounds contribute to the smell ofcloves, cinnamon, anise, and vanilla.
You might assume that aromatic compounds are so namedbecause they are smelly—and most of them are. However,smell is not what makes a compound aro-matic in the chemical sense. To a chemist, anaromatic compound is one that contains abenzene structure having a ring with sixcarbons.
What structure isfound in all aromaticcompounds? Wintergreen is
methyl salicylate.
C — OH
O
O — C — CH3— —
O— —
Figure 7 You can see the six-carbon benzene ring in these aro-matic compounds.
C — O — C — H
HO
—
H
—
OH
— —
Aspirin is acetyl salicylic acid.
(t)Aaron Haupt, (b)Mark Burnett
732 CHAPTER 24 Organic Compounds
Benzene Look at a model of benzene, C6H6, and its structuralformula in Figure 8. As you can see, the benzene molecule hassix carbon atoms bonded into a ring. The electrons shown asalternating double and single bonds that form the ring areshared by all six carbon atoms in the ring. This equal sharing ofelectrons is represented by the special benzene symbol—a circlein a hexagon. The sharing of these electrons causes the benzenemolecule to be very stable because all six carbon atoms arebound in a rigid, flat structure. Many compounds contain thisstable ring structure. The stable ring acts as a framework uponwhich new molecules can be built.
What is responsible for the stability of thebenzene ring?
Fused Rings Moth crystals have a distinct odor. One type ofmoth crystal is made of naphthalene (NAF thuh leen). This is adifferent type of aromatic compound that is made up of tworing structures fused together, as shown in Figure 9. Manyknown compounds contain three or more rings fused together.Tetracycline (teh truh SI kleen) antibiotics are based on a fusedring system containing four fused rings.
Substituted Hydrocarbons Usually a cheeseburger is a hamburger covered with melted
American cheese and served on a bun. However, you can makea cheeseburger with Swiss cheese and serve it on toast. Such sub-stitutions would affect the taste of this cheeseburger.
In a similar way, chemists change hydrocarbons into othercompounds having different physical and chemical properties.They may include a double or triple bond or add different atomsor groups of atoms to compounds. These changed compoundsare called substituted hydrocarbons.
NaphthaleneC10H8
H
H
H
H
H
H
C
C
C
CC
C
— —
——
——
— —
—
Space-filling modelStructural formula
Benzene symbol
Figure 8 Benzene, C6H6,can be represented in threeways.Infer Which method ofrepresenting benzene doyou think chemists usemost often?
Figure 9 Naphthalene used inmoth crystals is an example of afused-ring system.
Ken Frick
A substituted hydrocarbon has one or more of its hydrogenatoms replaced by atoms or groups of other elements. Dependingon what properties are needed, chemists decide what to add.Examples of substituted hydrocarbons are shown in Figure 10.
Alcohols and Acids Rubbing alcohol gets its name from thefact that it was used for rubbing on aching muscles. Rubbingalcohol is a substituted hydrocarbon. Alcohols are an importantgroup of organic compounds. They serve often as solvents anddisinfectants, and more importantly can be used as pieces toassemble larger molecules. An alcohol is formed when –OHgroups replace one or more hydrogen atoms in a hydrocarbon.Figure 10 shows ethanol, an alcohol produced by the fermenta-tion of sugar in grains and fruit.
Why are alcohols considered substitutedhydrocarbons?
Organic acids form when a carboxyl group, –COOH, is sub-stituted for one of the hydrogen atoms attached to a carbonatom. Look at Figure 10. The structures of ethane, ethanol, andacetic acid are similar. Do you see that acetic acid, found in vine-gar, is a substituted hydrocarbon? You know some other organicacids, too—citric acid found in citrus fruits, such as oranges andlemons, and lactic acid found in sour milk.
Figure 10 Substituted hydro-carbons come in a variety of forms.
Carbon Compounds inSpace About five percentof meteorites contain waterand carbon compounds.Carbon compounds, suchas formic acid and a form ofacetylene, have beendetected in outer spaceusing radio telescopes. Theareas where they are foundare thought to be regionsof space where new starsare forming.
C C
Cl Cl
Cl Cl
——
TetrachloroetheneC2Cl4
H — C — C
H
——
H
Acetic acidCH3COOH
——
O
OH
H — C — C — OH
H
——
H
——
HH
EthanolC2H5OH
Most ethanol, C2H5OH, often calledgrain alcohol, is obtained from corn.
Acetic acid is foundin vinegar.
Tetrachloroethene is acompound used in drycleaning.
SECTION 2 Other Organic Compounds 733(l)Aaron Haupt, (c,r)Timothy Fuller
734 CHAPTER 24 Organic Compounds
Self Check1. Describe three ways of representing a benzene molecule.
2. Explain why each of the following is considered a sub-stituted hydrocarbon: tetrachloroethene, ethanol, andacetic acid.
3. Explain why the benzene ring is so stable.
4. Explain why chemists might want to prepare substitutedhydrocarbons. Give two examples of possible substitutions.
5. Think Critically Chloroethane, C2H5Cl, can be used as aspray-on anesthetic for localized injuries. How doeschloroethane fit the definition of a substituted hydro-carbon? Diagram its structure.
SummaryAromatic Compounds
• A compound that contains a benzene ring iscalled an aromatic compound.
• A benzene molecule contains six carbonatoms bonded into a ring having alternatingdouble and single bonds.
• Aromatic compounds can contain two or morefused rings.
Substituted Hydrocarbons
• A hydrocarbon having one or more hydrogenatoms replaced by other atoms or groups ofatoms is called a substituted hydrocarbon.
• In alcohols, the �OH group is substituted fora hydrogen atom.
• Organic acids contain the group �COOH.
• Substituted hydrocarbons may contain atomsof elements, such as chlorine, bromine, fluo-rine, nitrogen, and sulfur.
6. Use Percentages As you have read, the odor of mer-captans can be detected in concentrations as low as0.5 parts per million. Express this concentration as apercent.
Substituting Other Elements Other atoms besideshydrogen and oxygen can be added to hydrocarbons. One ischlorine. When four chlorine atoms replace four hydrogenatoms in ethylene, the result is tetrachloroethene (teh truh kloruh eth EEN), a solvent used in dry cleaning. It is shown inFigure 10. Adding four fluorine atoms to ethylene makes a com-pound that can be transformed into a black, shiny material usedfor nonstick surfaces in cookware. Among other possible substi-tuted hydrocarbons are molecules containing nitrogen,bromine, and sulfur.
When sulfur replaces oxygen in the –OH group of an alcohol,the resulting compound is called a thiol, or more commonly amercaptan. Most mercaptans have unpleasant odors. This can beuseful to animals like the skunk shown in Figure 11.
Mercaptan odors are not only unpleasant, they are also pow-erful. You can smell skunk spray even in concentrations as low as0.5 parts per million. Though you might not think so, such apowerful stink can be an asset, and not just for skunks. In fact,smelly mercaptans can save lives. Recall that natural gas has noodor of its own so it is impossible to smell a gas leak. For this rea-son, gas companies add small amounts of a mercaptan to the gasto make people aware of leaks before they become dangerous.
gpscience.com/self_check_quiz
Figure 11 Strangely, smallconcentrations of foul-smellingcompounds are often found inpleasant-smelling substances. Forexample, the mercaptan in skunkspray is among the 834 compo-nents of coffee aroma.
Have you ever wondered how chemists changeone substance into another? You have learnedthat changing the bonding among atoms holdsthe key to that process.
Real-World QuestionHow can an alcohol change into an acid?
Goals■ Control the immediate environment of a
reaction to produce a specific compound.■ Gather evidence to form conclusions about
the identity of a new compound formedfrom a chemical reaction.
Materialslarge test tube and stopper0.01M potassium permanganate
WARNING: Always handle chemicals with care;immediately flush any spill with water.
Procedure1. Pour 1 mL of 0.01M potassium perman-
ganate solution and 1 mL of 6M sodiumhydroxide solution into a test tube.
2. Add 3 drops of ethanol to the test tube.
3. Stopper the test tube. Gently shake it for1 min. Observe and record any changes inthe solution for 5 min.
Conclude and Apply1. Identify the structural formula for ethanol.
2. Identify the part of a molecule that makesa compound an alcohol.
3. Identify the part of a molecule that identi-fies a compound as an organic acid.
4. Explain how you know that a chemicalchange took place in the test tube.
5. Predict the formula of the acid producedwhen ethanol undergoes a chemical reac-tion in the presence of potassium perman-ganate.
6. Identify the chemical name of the acid pro-duced from ethanol that is found in vinegar.
Alcohol and Organic Acids
Design a table and record what changestake place in the color of the solution.Compare your observations with those ofother students in your class. For more help,refer to the Science Skill Handbook.
LAB 735Tim Courlas/Horizons Companies
736 CHAPTER 24 Organic Compounds
What is petroleum?Do you carry a comb in your pocket or purse? What is it
made from? If you answer plastic, you are probably right, but doyou know where that plastic came from? Chances are it camefrom petroleum—a dark, flammable liquid, often called crudeoil, that is found deep within Earth. Like coal and natural gas,this dark, foul-smelling substance is formed from the remains of
fossilized material. For this reason these substancesoften are called fossil fuels.
How can a thick, dark liquid like petroleum betransformed into a hard, brightly colored, usefulobject like a comb? The answer lies in the nature ofpetroleum. Petroleum is a mixture of thousands ofcarbon compounds. To make items such as combs,the first step is to extract the crude oil from itsunderground source, as shown in Figure 12. Then,chemists and engineers separate the crude oil intofractions containing compounds with similar boil-ing points. The separation process is known as frac-tional distillation. It takes place in petroleumrefineries. If you have ever driven past a refinery, youmay have seen big, metal towers called fractionatingtowers. They often rise as high as 35 m and can be18 m wide and have pipes and metal scaffoldingattached to the outside.
Petroleum—A Sourceof Carbon Compounds
Reading Guide
■ Explain how carbon compoundsare obtained from petroleum.
■ Determine how carbon com-pounds can form long chains.
■ Define the terms polymerizationand depolymerization.
Petroleum gives us fuels, plastics,clothing, and many other products.
Review Vocabularycondense: to change from gaseousto liquid state
New Vocabulary
• polymer
• monomer
• polyethylene
• depolymerization
Ocean surface
Oil platform
Ocean floor
Oil wells
Natural gas
Rock layers
Oil
Figure 12 Drilling for petro-leum beneath the ocean floorrequires huge platforms.
SECTION 3 Petroleum—A Source of Carbon Compounds 737
The Tower Inside the tower is a series ofmetal plates arranged like the floors of abuilding. These plates have small holes sothat vapors can pass through. On the out-side you can see a maze of pipes at variouslevels. The tower separates crude oil intofractions containing compounds having arange of boiling points. Within a fraction,boiling points may range more than 100°C.
How It Happens The crude petroleumat the base of the tower is heated to morethan 350°C. At this temperature mosthydrocarbons in the mixture becomevapor and start to rise. The higher boilingfractions reach only the lower plates beforethey condense, forming shallow pools thatdrain off through pipes on the sides of thetower and are collected.
Fractions with lower boiling pointsmay climb higher to the middle platesbefore condensing. Finally, those with thelowest boiling points condense on the top-most plates or never condense at all andare collected as gases at the top of thetower. Figure 13 shows some typical frac-tions and how they are used.
Why don’t the condensed liquids fall back through the holes?The reason is that pressure from the rising vapors prevents this.In fact, the separation of the fractions is improved by the inter-action of rising vapors with condensed liquid. The processesinvolved vary. For example, some towers add steam at the bot-tom to aid vaporization. The design and process used depend onthe type of crude oil and on the fractions desired.
Uses for Petroleum Compounds Some fractions are used directly for fuel—the lightest frac-
tions from the top of the tower include butane and propane. Thefractions that condense on the upper plates and contain fromfive to ten carbons are used for gasoline and solvents. Belowthese are fractions with 12 to 18 carbons that are used forkerosene and jet fuel. The bottom fractions go into lubricatingoil, and the residue is used for paving asphalt. Figure 14 showsthe variety of useful products that can be obtained from petro-leum, in addition to its use as a fuel.
40°C � 200 °C
Above 300°C
Above 350°C
250°C � 400 °C
175°C � 275 °C
Gasoline
Kerosene
Jet fuel and diesel oil
Lubricating oil
Asphalt
Hydrocarbon gasesused for fuels and
plastics
Below 20°C
Heatedcrude oil
Figure 13 Typical fractions areseparated in a fractionating towerby their boiling points.Infer How might these fractions beseparated further?
Figure 14
738 CHAPTER 24 Organic Compounds
PRINTING INKThe ink used innewspapers is madefrom carbon black,another productfrom petroleum.
PLASTICS The durabilityof hard plastic makes itthe ideal material for acell phone keypad.
FUELS This commuter jet is being refueled at an air-port. Most of the world’spetroleum is still used inthe form of fuel.
MEDICINES The activeingredient in aspirinused to be extractedfrom the bark ofwillow trees.Todayit is manufacturedfrom petroleum.
Petroleum, or crude oil, provides the raw materialfor a huge number of products that have becomeessential to modern life. After it has been refined,
petroleum can be used to make various types of fuel,plastics, and synthetic fibers, as well as paint, dyes,and medicines.
FABRICS Like the fleece used to make these gloves, many modern fabrics are made from synthetic, rather than natural,fibers. Some of the most popular syn-thetic fibers—polyester andnylon are petroleum-based.
SECTION 3 Petroleum—A Source of Carbon Compounds 739
PolymersDid you ever loop together strips of paper to make paper
chains for decorations, or have you ever strung paper clipstogether? A paper chain can represent the structure of a polymeras shown in Figure 15. Some of the smaller molecules frompetroleum can act like links in a chain. When these links arehooked together, they make new, extremely large moleculesknown as polymers. The small molecule, which forms a link inthe polymer chain, is called a monomer. Mono means one.
How are polymers similar to paper chains orlinked paper clips?
Common Polymers One common polymer or plastic ismade from the monomer ethene or ethylene. Under standardroom-temperature conditions, this small hydrocarbon is a gas.However, when ethylene combines with itself repeatedly, itforms a polymer called polyethylene. Polyethylene (pah lee EHthuh leen) is used widely in shopping bags and plastic bottles.Another common polymer is polypropylene (pah lee PRO puhleen) used to make glues and carpets. Often two or more differ-ent monomers, known as copolymers, combine to make onepolymer molecule.
Polymers can be made light and flexible or so strong thatthey can be used to make plastic pipes, boats, and even someauto bodies. In many cases, they have replaced natural buildingmaterials, such as wood and metal. Because so many things usedtoday are made of synthetic polymers, some people call this“The Age of Plastics.”
Visualizing PolymersProcedure1. Use paper clips to repre-
sent monomers in a syn-thetic polymer. Hook about20 together to make achain.
2. Cut 20 strips of coloredpaper and mark each witha different letter of thealphabet from A to T.
3. Assemble these strips inrandom order to make apaper chain.
Analysis1. Imagine both chains
extended to contain10,000 or more units.Compare them in terms ofease of construction anddegree of complexity.
2. Compare the paper chainsmade by your class. Howmany different combina-tions of letters are there?
Figure 15 Imagine this paper chain extended by 10,000 units. Thenimagine each link as a monomer. Now you have an idea of what a typicalpolymer used to make plastic looks like.
740 CHAPTER 24 Organic Compounds
Designing Polymers The properties of polymers dependmostly on which monomers are used to make them. Also, likehydrocarbons, polymers can have branches in their chains. Theamount of branching and the shape of the polymer greatlyaffect its properties.
Polymer materials can be shaped in many ways. Some aremolded to make containers or other rigid materials. Sometimesthe same polymer can take two completely different forms. Forexample, polystyrene (pah lee STI reen) that is made fromstyrene, shown in Figure 16, forms brittle, transparent cases forCDs and lightweight, opaque foam cups and packing materials.To make this transformation, a gas such as carbon dioxide isblown into melted polystyrene as it is molded. Bubbles remainwithin the polymer when it cools, making polystyrene foam anefficient insulator.
Other polymers can be spun into threads, which are used tomake clothing or items such as suitcases and backpacks. Fiberscan be made strong and durable for products that receive wearand tear. Others can resist strong impacts. For example, bullet-proof vests are made of a tightly woven, synthetic polymer.Polymer fibers also can be made stretchy and resilient for fabricproducts like exercise garments. Some polymers remain rigidwhen heated, but others become soft and pliable when heatedand harden again when cooled.
Name some applications of polymer fibers.
Figure 16 Processing can modify a polymer’s properties.Polystyrene used in CD cases is clear, hard, and brittle.Polystyrene used in cups is opaque, lightweight, and foamy.
Topic: PolymersVisit gpscience.com for Web Linksto information about polymers andplastics.
Activity Find out which poly-mers can be recycled and how toidentify them.
(l)Geoff Butler, (r)Charles D. Winters/Photo Researchers
SECTION 3 Petroleum—A Source of Carbon Compounds 741
Self Check1. Identify what physical property is used to separate
petroleum fractions.
2. Explain why some fuels are referred to as fossil fuels.
3. Explain why polymers made from the same monomercan have physical properties that vary greatly.
4. List some of the fuels obtained from petroleum by frac-tional distillation.
5. Describe why depolymerization can be an expensiveprocess.
6. Think Critically Based on the names of the polymersin this section, what do you think polymers made fromthe monomers terpene and urethane are called?
SummaryWhat is petroleum?
• Petroleum, often called crude oil, is a dark,flammable liquid that is formed from fos-silized materials.
• Carbon compounds in petroleum can beseparated using fractional distillation.
• Petroleum fractions are used directly for fueland to make useful substances, such as plastics.
Polymers
• Polymers are long chains of repeating chemi-cal units called monomers.
• Polymers can be designed with specific prop-erties, such as strength and flexibility.
• Common polymers are polyethylene andpolypropylene.
• Depolymerization is the process of breaking apolymer into its components.
7. Calculate If the average molecular weight of anamino acid is 112, find the approximate molecular weight of a protein containing 122 amino acids.
Other Petroleum Products are obtained byfurther purifying petroleum fractions using dif-ferent techniques to isolate individual com-pounds. After these are separated, they can beconverted into substituted hydrocarbons, as youlearned in the last section. Chemists use these tomake products ranging from medicines such asaspirin to insecticides, printers’ ink, and flavor-ings. Also, aromatic dyes from petroleum havereplaced natural dyes, such as indigo andalizarin, almost completely. The first syntheticdye was a bright purple called mauve that wasdiscovered accidentally in coal tar compounds.
Depolymerization Polymers have been used so widely thatdisposal has caused problems, because many polymers do notdecompose. One way to combat this is by recycling, whichrecovers clean plastics for reuse in new products, as shown inFigure 17. Many communities recycle plastics.
Another approach involves a process called depolymerization,that uses heat or chemicals to break the long polymer chain intoits monomer fragments. These monomers can then be reused.However, each polymer requires a different process, and muchresearch is needed to make this type of recycling economical.
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Figure 17 This gazebo, likemany other structures, is built from100 percent recycled plastics.
Biological Polymers Like the polymers that are used to make
the plastics and fibers, biological polymersare huge molecules. Also, they are made ofmany smaller monomers that are linkedtogether. The monomers of biological poly-mers are usually larger and more complexin structure. Still, you can picture a biologi-cal monomer as one link in a very longchain.
Many of the important biological com-pounds in your body are polymers. Amongthem are the proteins, which often containhundreds of units.
ProteinsProteins are large organic polymers
formed from organic monomers calledamino acids. Even though only 20 aminoacids are commonly found in nature, theycan be arranged in so many ways that mil-lions of different proteins exist. Proteins
come in numerous forms and make up many of the tissues inyour body, such as muscles and tendons, as well as your hair andfingernails. In fact, proteins account for 15 percent of your totalbody weight.
Biological CompoundsReading Guide
■ Compare and contrast proteins,nucleic acids, carbohydrates,and lipids.
■ Identify the structure of polymersfound in basic food groups.
■ Identify the structure of largebiological polymers.
All life processes depend on largebiological compounds.
Each amino acidcontains acarboxylic acid(–COOH) group.
Cysteine
H — C — H
S — H
—
H — N — C — C
—
H
—
H
O
OH
——
Each amino acidcontains anamine (–NH2) group.
PeptideGlycyl cysteinate
H
H — C — H
S — H
—
N C — C
—
H
O
OH
——
O
N — C — C
H
——
H
H
H
——
Peptide bondslink moleculesof amino acids.
HOH
Water forms inreaction.
Figure 18 In a protein polymer,peptide bonds link together mole-cules of amino acids.
SECTION 4 Biological Compounds 743
Protein Monomers Amino acids are the monomers thatcombine to form proteins. Two amino acids are shown inFigure 18. The –NH2 group is the amine group and the–COOH group is the carboxylic acid group. Both groupsappear in every amino acid.
Amine groups of one amino acid can combine with thecarboxylic acid group of another amino acid, linking themtogether to form a compound called a peptide as also shown inFigure 18. The bond joining them is known as a peptide bond.When a peptide contains a large number of amino acids—about50 or more—the molecule is called a protein.
Approximately how many amino acid units doesa protein contain?
Protein Structure Long protein molecules tend to twist andcoil in a manner unique to each protein. For example, hemoglo-bin, which carries oxygen in your blood, has four chains that coilaround each other as shown in Figure 19. Each chain containsan iron atom that carries the oxygen. If you look closely, you cansee all four iron atoms in hemoglobin.
When you eat foods that contain proteins, such as meat,dairy products, and some vegetables, your body breaks down theproteins into their amino acid monomers. Then your body usesthese amino acids to make new proteins that form muscles,blood, and other body tissues.
Figure 19 Four peptide chains coilaround each other in the protein poly-mer hemoglobin. Each chain has anatom of iron, which carries oxygen.
Iron atomcarrying oxygen
Organic Chemist Organicchemists find challenges inmany industries. Areassuch as pharmaceuticals,polymers, adhesives, fuels,food additives, cosmetics,and environmental scienceall involve organic chem-istry. To prepare for thiscareer, students shouldstudy as much science aspossible in high school, andnot neglect math. Math isimportant in both appliedand theoretical organicchemistry.
David M. Phillips/Visuals Unlimited
744 CHAPTER 24 Organic Compounds
Nucleic AcidsThe nucleic acids are another important group of organic
polymers that are essential for life. They control the activitiesand reproduction of cells. One kind of nucleic acid, calleddeoxyribonucleic (dee AHK sih ri boh noo klay ihk) acid orDNA, is found in cells where it codes and stores genetic infor-mation. This is known as the genetic code.
Nucleic Acid Monomers The monomers that make upDNA are called nucleotides. A nucleotide is a complex moleculethat contains one of four organic bases, a sugar, and a phosphateunit. DNA nucleotides are in chains that are unique to an organ-ism. Two nucleotide chains twist around each other formingwhat resembles a twisted ladder called a double helix. The rungsof the ladder are paired organic bases. There only are two differ-ent pairs that can form, as shown in Figure 20. Your geneticcode gives instructions for making other nucleotides and pro-teins needed by your body.
Topic: DNA FingerprintingVisit gpscience.com for Web linksto information about DNAfingerprinting.
Activity Research how DNA fin-gerprints are being used besidessolving crimes and prepare a shortreport on one of them.
Selecting a Balanced Diet
What do you like to eat? You probablychoose your foods by how good they
taste. A better way might be to look at theirnutritional value. Your body needs nutri-ents like proteins, carbohydrates, and fats togive it energy and help it build cells. Almostevery food has some of these nutrients in it.The trick is to pick your foods so you don’tget too much of one thing and not enoughof another.
Identifying the ProblemThe table on the right lists
some basic nutrients for a vari-ety of foods. The amount ofthe protein, carbohydrate, andfat is recorded as the numberof grams in 100 g of the food.By examining these data, canyou select the foods that bestprovide each nutrient?
Solving the Problem 1. Using the table, list the foods that supply
the most protein and carbohydrates.What might be the problem with eatingtoo many potato chips?
2. In countries where meat and dairy prod-ucts are hard to get, people eat a lot offood made from soybeans. Can you thinkof reasons why people might wish tosubstitute meat and dairy products withsoybean based products?
Figure 20 DNA models show how nucleotides arearranged in DNA. Each nucleotide looks like half of aladder rung with an attached side piece. As you cansee, each pair of nucleotides forms a rung on the lad-der, while the side pieces give the ladder a littletwist that gives DNA the name double helix.
DNA Fingerprinting Human DNA contains more than 5 bil-lion base pairs. The DNA of each person differs in some wayfrom that of everyone else, except for identical twins, who sharethe same DNA sequence. The unique nature of DNAoffers crime investigators a way to identify criminals from hairor fluids left at a crime scene. DNA from bloodstains or cells insaliva found on a cigarette can be extracted in the laboratory.Then, chemists can break up the DNA into its nucleotide com-ponents and use radioactive and X-ray methods to obtain a pic-ture of the nucleotide pattern. Comparing this pattern to onemade from the DNA of a suspect can link that suspect to thecrime scene.
Carbohydrates If you hear the word carbohydrate, you
may think of bread, cookies, or pasta. Haveyou heard of carbohydrate loading by ath-letes? Runners, for example, often preparefor a long-distance race by eating, or load-ing up on, carbohydrates in foods such asvegetables and pasta. Carbohydrates arecompounds containing carbon, hydrogen,and oxygen, that have twice as many hydro-gen atoms as oxygen atoms. Carbohydratesinclude the sugars and starches.
746 CHAPTER 24 Organic Compounds
Sugars Sugars are a major group of carbohydrates, as shownin Figure 21. The sugar glucose is found in your blood and alsoin many sweet foods such as grapes and honey. Common tablesugar, known as sucrose, is broken down by digestion into twosimpler sugars—fructose, often called fruit sugar, and glucose.Unlike starches, sugars provide quick energy soon after eating.
Starches Starch, shown in Figure 22, is a carbohydrate that isalso a polymer. It is made of units or monomers of the sugar glu-cose. During digestion, the starch is broken down into smaller mol-ecules of glucose and other similar sugars, which release energy inyour body cells.
Athletes, especially long-distance runners, use starches toprovide high-energy, long-lasting fuel for the body. The energyfrom starches can be stored in liver and muscle cells in the formof a compound called glycogen. During a long race, this storedenergy is released, giving the athlete a fresh burst of power.
LipidsFats, oils, and related compounds make up a group of
organic compounds known as lipids. Lipids include animal fatssuch as butter, and vegetable oils such as corn oil. Lipids containthe same elements as carbohydrates but in different propor-tions. For example, lipids have fewer oxygen atoms and containcarboxylic acid groups.
H OH
C C
OH
C O
C C
Glucose C6H12O6
HO
H
OH
HH
——
H
—
— —
CH2OH
—
O
CH2OH
H OH
C C
OH
C O
C C
HH
——
—
H
—
— —
CH2OH
H OH
C C
OH
C O
C C
HHH
——
—
H
—
— —
O
H H
O O
CH2OH
H OH
C C
OH
C O
C C
HHH
——
—
H
—
— —
O
CH2OH
H OH
C C
OH
C O
C C
HHH
——
—
H
—
— —
C
H
C
HOCH2
O
CH2OH
Sucrose C12H22O11
H OH
C C
OH
C O
CH2OH
O
CH
——
—
H
—
HO
—
H
—
—
H
C
——
OH
C
—
C CHO
H HC
H
Figure 21 Sucrose and glucoseare sugars found in foods. Fruitscontain glucose and another simplesugar called fructose. Explain why sugars arecarbohydrates.
• Sugars are carbohydrates that provide energyto your body and starches are large polymersbuilt of sugar units.
• Lipids include fats and oils.
6. Use Percentages You have read that your body isabout 15 percent protein. Calculate the weight of protein in your body in kilograms.
Fats and Oils These substances are similar in structure tohydrocarbons. They can be classified as saturated or unsaturated,according to the types of bonds in their carbon chains. Saturatedfats contain only single bonds between carbon atoms. Unsaturatedfats having one double bond are called monounsaturated, andthose having two or more double bonds are called polyunsatu-rated. Animal lipids or fats tend to be saturated and are solids atroom temperature. Plant lipids called oils are unsaturated and areusually liquids, as shown in Figure 23. Sometimes hydrogen isadded to vegetable oils to form more saturated solid compoundsknown as hydrogenated vegetable shortenings.
Have you heard that eating too much fat can be unhealthy?Evidence shows that too much saturated fat and cholesterol inthe diet may contribute to some heart disease and that unsatu-rated fats may help to prevent heart disease. It appears that sat-urated fats are more likely to be converted to substances that canblock the arteries leading to the heart. A balanced diet includessome fats, just as it includes proteins and carbohydrates.
Cholesterol is another lipid that is often in the news. It isfound in meats, eggs, butter, cheese, and fish. Also, some choles-terol is produced by the body to build cell membranes. It is alsofound in bile, a digestive fluid. Too much cholesterol may causeserious damage to heart and blood vessels, similar to the dam-age caused by saturated fats.
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Figure 23 At room tempera-ture, fats are normally solids, andoils are usually liquids.
Real-World QuestionAre esters aromatic compounds? Organic compounds known as acidsand alcohols react to form another type of organic compound calledan ester. Esters frequently produce a recognizable and often pleasantfragrance, even though they are not aromatic in the chemicalsense—they might not contain a benzene ring. Esters are responsiblefor many fruit flavors, such as apple, pineapple, pear, and banana.How do an acid and an alcohol combine to produce a compound withdifferent characteristics? Can the presence of the new compoundformed be detected by its odor?
ProcedureWARNING: Any compound you can smell has entered your body, andunknown compounds can be toxic or corrosive. To detect an aroma safely,hold the container about 10 cm in front of your face and wave your handover the opening to direct air currents to your nose.
See the illustration below for the proper way to detect odors in thelaboratory.
Goals■ Prepare an ester from
an alcohol and an acid.■ Detect the results of
the reaction by theodor of the product.
Materialsmedium-size test tubetest-tube holder250-mL beaker10-mL graduated cylinderwaterhot platering stand thermometersalicylic acid (1.0 g)amyl alcohol (2 mL)concentrated sulfuric acid
(1 mL to be added byteacher)
Safety Precautions
WARNING: Sulfuric acid iscaustic. Avoid all contact.Mix all the contents togetherusing a glass stirring rod. Donot use the thermometer asa stirring rod.
PREPARING AN ESTER
748 CHAPTER 24 Organic Compounds
dor, waft the vaporrd your face gently.
1. Add about 150 mL of water to the beaker and heat it on the hotplate to 70°C.
2. Place approximately 1 g of salicylic acid in a test tube. Does thismaterial have an odor?
3. Add 2 mL of amyl alcohol to the test tube. Before adding it, check to see if thiscompound has an odor. If so, try to remember what it smells like.
4. Ask your teacher to add carefully 1 mL of concentrated sulfuric acid.
5. Place the test tube in the hot water and leave it untouched for about 12 to 15minutes.
6. Remove the tube from the hot water using a test-tube holder and allow it tocool. Check to see if you can detect a new aroma.
Analyze Your Data1. What did you smell in step 6?
2. Look closely at the surface of the liquid in the test tube. Do you see any smalldroplets of an oily substance? What do you think it is?
Conclude and Apply1. Predict What esters would form if amyl alcohol was replaced by the following
alcohols; methyl, ethyl, propyl, and isobutyl.
2. Predict Look at the equation for the reaction below. One product is given.What do you think is the second product formed in this reaction?
LAB 749
O
— —
CH3 (CH2)3 CH2OH
H H H H H
H H H H H
——
——
——
——
——
C — OH
O
— —OH
— C — O — C — C — C — C — C — H ?� �→OH
—
Write a description of your experiment inyour Science Journal. Suggest how youmight modify the experiment to produce adifferent ester. For more help, refer to theScience Skill Handbook.
Matt Meadows
In 1953, American chemist Patsy Shermaninvented a way to protect fabrics fromaccidental spills. Strangely enough, this
discovery came about because of an acciden-tal spill in her lab.
The technicians were trying to develop anew kind of latex rubber for jet aircraft fuellines when some of the latex mixture acci-dentally splashed on an assistant’s canvastennis shoe. The result was remarkable.
The latex mixture didn’t stain the shoeor change it in any way. But it simply wouldnot come off. Neither soap nor alcohol norany other cleaning material could removethe stubborn mixture from the shoe. In fact,water beaded and ran off the shoe, much aswater runs off a duck’s back.
Although her assistant was frustrated by themixture’s staying power, Sherman was inspired.She realized that it could be used to protect fab-rics from oil, water, and dirt. She spent three
years working with anotherchemist to perfect the prod-uct, which came on the mar-ket in 1956. The substituted
hydrocarbon compound that Sherman devel-oped makes fabrics more durable as well asstain resistant. It bonds to the fibers in the fab-ric and protects them like an invisible shield.
The fabric protector invented by Shermanwas used widely to protect many householdproducts, and some clothing, for over 40years. It was long believed to be chemicallyinert, however, later studies showed that itdoes break down slowly, yielding a chemicalcalled PFOS. This substance can persist forlong periods in the environment and can bindto human and animal proteins. For this rea-son, Sherman’s original product was removedfrom the market and replaced by a similarcompound that has been shown to presentno danger to the environment.
Now retired, Patsy Sherman often speaksto students. She stresses that a creative mindis a scientist’s best tool. “Anyone can becomean inventor,” she insists, “as long as they keepan open and inquiring mind and never over-look the possible significance of an accidentor apparent failure.”
A S PILLfor a Spill
“How many greatdiscoveries wouldnever have occurredwere it not foraccidents?” asksSherman.
Experiment Pour a small amount of water on a pieceof cloth that has been treated with fabric protector. Do thesame to a piece of untreated cloth. What happened to thewater in both cases? What happened to the pieces of cloth?
Use the table below to answer questions 17 and 18.
17. Using the table above, plot the number ofcarbon atoms on one axis and the boilingpoint on the other axis on a graph. Usethe graph to predict the boiling points ofbutane, octane, and dodecane (C12H26).
18. How might your graph be different, ifone of the hydrocarbons you plotted had abranched chain instead of a straight chain?
19. Look at the fiber content of ten items ofyour clothing. Note the percentages ofsynthetic or natural fibers. Determine thecontents of these items by making a circlegraph comparing the average percentagesof natural and synthetic fibers. Hint: cot-ton, linen, wool, and silk are natural fibers.
20. Infer A healthy diet contains a variety ofnutrients, including fats. However, as youhave read, saturated fats have some draw-backs. Based on this knowledge, howwould you modify your diet to make ithealthier? What general rule would youapply in making your choices?
21. Classify the following compounds assaturated, unsaturated, or substitutedhydrocarbons: hexene, isopropyl alcohol,2-chlorobutane, pentadiene, and butyric acid.
22. Explain why the toughness and durabilityof many plastic polymers can be both anasset and a liability.
23. Describe how the structures of propylalcohol and isopropyl alcohol might differ,although both have the formula C3H8O.
24. Explain single, double, and triple bonds inhydrocarbons by drawing a chain of car-bon that shows each type of bond.
Hydrocarbons
N Point (°C)
M 162
E �89
P �42
25. Solve One-Step Equations Although physi-cians disagree about what is a healthylevel of blood cholesterol, many feel thatlevels above 200 mg/dL are harmful.A patient’s blood cholesterol level meas-ured 228 mg/dL. After two months ona low-fat diet, it dropped to 210 mg/mL.By what percent did the patient’s choles-terol level decrease?
26. Use Percentages The label on a bottle ofvinegar containing 473 mL says thatthe contents contain 6 percent acid byvolume. How many milliliters of aciddoes this bottle contain?
Use the graph below to answer question 27.
27. Use Statistics The graph above showsthe percent of the U. S. populationserved by curbside recycling from1990 to 1999. Calculate what percentof the population received servicefrom 1992 to 1999.
Record your answers on the answer sheetprovided by your teacher or on a sheet of paper.
1. What atoms make up a hydrocarbonmolecule?A. oxygen, carbon, and hydrogenB. nitrogen and carbonC. carbon and hydrogenD. oxygen and hydrogen
Use the illustrations below to answer questions
2 and 3.
2. What is the chemical formula of the com-pound shown above?A. C3H3 C. C6H6B. CH8 D. C3H8
3. What is the name of this compound?A. propane C. isopreneB. heptane D. methane
4. Which of these contains carbon, hydrogen,and oxygen, and has twice as manyhydrogen atoms as oxygen atoms?A. hydrocarbon C. alcoholB. carbohydrate D. isomer
5. Which of the following is NOT a polymerderived from petroleum?A. polypropylene C. polyethyleneB. acetylene D. polystyrene
6. Which of the following is a type of recy-cling that breaks up the polymers into theiroriginal monomers?A. fractionation C. isomerizationB. saturation D. depolymerization
Use the illustrations below to answer questions
7 and 8.
7. Each of these compounds can be consid-ered to be a substituted hydrocarbon. Whatdoes this mean?A. Their basic structural unit is a benzene
ring.B. They are inorganic compounds.C. One or more of the hydrogen atoms is
replaced by atoms or groups of otherelements.
D. They are polymers.
8. Which of these compounds is an alcoholthat is often obtained from corn?A. ethanolB. acetic acidC. tetrachloroetheneD. ethene
9. Which of these best shows the shape of thenucleic acid DNA?
A. C.
B. D.
C C
Cl Cl
Cl Cl
——
TetrachloroetheneC2Cl4
H — C — C
H
——
H
Acetic acidCH3COOH
——
O
OH
H — C — C — OH
H
——
H
——
HH
EthanolC2H5OH
H — C — C — C — H
H
H
——
H
H
——
H
H
——
754 STANDARDIZED TEST PRACTICE
STANDARDIZED TEST PRACTICE 755
Record your answers on the answer sheetprovided by your teacher or on a sheet of paper.
10. Describe the type of bonds carbon canform.
Use the illustrations below to answer question 11.
11. These molecules are isomers. Given theinformation that these are hydrocarbons,write their chemical formulas.
12. Describe the general relationship betweenmelting point, boiling point, and theamount of branching in an isomer.
13. Describe some properties and uses ofalcohols.
14. What is the process used to separatepetroleum compounds called? On whatphysical property is this process based?
15. Identify some fractions into which crudepetroleum is separated.
Record your answers on a sheet of paper.
16. Describe useful properties of polymers.List several objects made of polymermaterial that would likely have beenmade of wood or metal in the past.
17. Identify the polymer material used tomake CD cases and foam drinking cups.How can it be used to create two typesof containers that have such differentproperties?
Use the illustration below to answer questions
18 and 19.
18. How is this paper chain a good represen-tation of a protein? Describe the impor-tance of proteins in the human body.
19. Draw a section of this polymer with threeor four links using the formulas of the twoamino acids given in the chapter and labeleach link.
20. When you read or hear about cholesterolin the news, it is usually associated withnegative effects on the heart and bloodvessels. Why does the body make a sub-stance that can potentially damage thecirculatory system?
21. Plastic polymers can be prepared cheaplyto replace more expensive natural sub-stances. However, disposal presents prob-lems because they do not decomposereadily in landfills. Describe two ways ofsolving this problem.
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Formulas Think about structural formulas before answeringthe question.
Question 11 Remember how many bonds each carbon atomcan form.
