DistillationDistillation

•increase with increasing number of carbons

• more atoms, more electrons, more opportunities for induced dipole-induceddipole forces

HeptaneHeptanebp 98°Cbp 98°C

OctaneOctanebp 125°Cbp 125°C

NonaneNonanebp 150°Cbp 150°C

Boiling Points

Distillation

Chapter 7: Petroleum

The Driving Force of Energy

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Courtesy PhotoDisc, Inc. /Getty Images

Distilling pure water from strong tea.

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Courtesy Ken Karp

Figure 7.7: Distillations.

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Crude Oil

• The differences in boiling points are used to separate hydrocarbons in crude oil.

• Heating to higher temperatures produces gases that are removed and cooled.

Figure 7.8: Schematic diagram of fractional distillation of crude oil.

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A fractioning tower.

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Courtesy Brett Frooner/The Image Bank/Getty Images

Crude oilCrude oil

Crude oilCrude oil

Refinery gasRefinery gasRefinery gasRefinery gas

CC11-C-C44

Light gasolineLight gasoline(bp: 25-95 °C)(bp: 25-95 °C)

Light gasolineLight gasoline(bp: 25-95 °C)(bp: 25-95 °C)

CC55-C-C1212

NaphthaNaphtha(bp 95-150 °C)(bp 95-150 °C)

NaphthaNaphtha(bp 95-150 °C)(bp 95-150 °C)

KeroseneKerosene(bp: 150-230 °C)(bp: 150-230 °C)

KeroseneKerosene(bp: 150-230 °C)(bp: 150-230 °C)

CC1212-C-C1515

Gas oilGas oil(bp: 230-340 °C)(bp: 230-340 °C)

Gas oilGas oil(bp: 230-340 °C)(bp: 230-340 °C)

CC1515-C-C2525

ResidueResidueResidueResidue

                                                                                                                   

What is common between a Potato Canon and a Car

http://auto.howstuffworks.com/engine2.htm

Figure 7.1: Schematic of a four-cylinder engine.

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Understanding the Cycles http://auto.howstuffworks.com/engine4.htm

http://www.keveney.com/otto.html

Intake. During the intake stroke, the piston moves downward, drawing a fresh charge of vaporized fuel/air mixture.  The illustrated engine features a 'poppet' intake valve which is drawn open by the vacuum produced by the intake stroke.  Some early engines worked this way, however most modern engines incorporate an extra cam/lifter arrangement as seen on the exhaust valve.  The exhaust valve is held shut by a spring (not illustrated here).

Compression. As the piston rises the poppet valve is forced shut by the increased cylinder pressure.  Flywheel momentum drives the piston upward, compressing the fuel/air mixture.

Power. At the top of the compression stroke the spark plug fires, igniting the compressed fuel.  As the fuel burns it expands, driving the piston downward.

Exhaust. At the bottom of the power stroke, the exhaust valve is opened by the cam/lifter mechanism.  The upward stroke of the piston drives the exhausted fuel out of the cylinder.

Figure 7.2: (a) The beginning of the intake stroke. (b) The middle of the intake stroke. (c) The beginning of the compression stroke. (d) The beginning of the power stroke. (e) The beginning of the exhaust stroke.

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Figure 7.3: The compression ratio is volume A divided by volume B.

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Figure 7.4: Smooth ignition and knocking.

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Three grades of gasoline and their octane ratings.

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Courtesy Tannen Mauryl/The Image Works

Figure 7.5: A combination of 2,2,4-trimethylpentane and heptane is used to evaluate octane ratings.

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Figure 7.6: Catalytic converter.

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Removing old paint containing lead from the interior of a building.

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Courtesy Seth Resnick/Liaison/Getty Images

An MTBE warning label on a gasoline pump in California: “The state of California has determined that the use of this chemical presents a significant risk to the environment.

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Courtesy Bill Grafton/The Reynolds Group.

Tank truck delivering gasoline to a gas station.

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Courtesy Tony Freeman/PhotoEdit

Figure 7.5: A combination of 2,2,4-trimethylpentane and heptane is used to evaluate octane ratings.

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Reforming–increases branching of hydrocarbon chainsbranched hydrocarbons have better burningcharacteristics for automobile engines

Petroleum Refining

Figure 7.10: Isomerization of hexane to isohexane (2-methylpentane).

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Figure 7.11: Cyclization of hexane to cyclohexane.

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Figure 7.12: Aromatization of cyclohexane to benzene.

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•Cracking–converts high molecular weight hydrocarbons to more useful, low molecular weight ones

Petroleum Refining

Figure 7.9: Catalytic cracking.

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Installing a tank of natural gas.

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Courtesy Paul S. Howell/Liaison Agency, Inc./Getty Images

A bus powered by methanol.

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Courtesy Vanessa Vick/Photo Researchers

Burning gasoline and other fossil fuels adds carbon dioxide to the atmosphere.

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Courtesy PhotoDisc Inc./Getty Images

A greenhouse.

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Courtesy Michael George/Bruce Coleman, Inc.

Figure 8.7: The greenhouse effect.

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Figure 8.8: Planetary greenhouse effects.

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Landscapes of Venus, Earth, and Mars.

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Courtesy Mark Marten/NASA/Science Source/Photo Researchers

Courtesy Philip & Karen Smith/Stone/Getty Images

Courtesy NASA/Phototake

Figure 8.9: Global temperature changes.

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Will Alaska look like this as a result of the greenhouse effect?

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Courtesy Peter Newton/Stone/Getty Images

An electric car.

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Courtesy Solectria Corporation

Banks of wind turbines convert the energy of the wind into electricity.

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Figure 7.13: The essentials of a typical fuel cell.

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Chemistry of a Fuel Cell

Anode side:2H2 => 4H+ + 4e-

Cathode side:O2 + 4H+ + 4e- => 2H2O

Net reaction:2H2 + O2 => 2H2O

 

                                                                                                                  

                              

http://videos.howstuffworks.com/fuel-cell-video.htm

•The anode, the negative terminal of the fuel cell, has several jobs. It conducts the electrons that are freed from the hydrogen molecules so that they can be used in an external circuit. It has channels etched into it that disperse the hydrogen gas equally over the surface of the catalyst. •The cathode, the positive post of the fuel cell, has channels etched into it that distribute the oxygen to the surface of the catalyst. It also conducts the electrons back from the external circuit to the catalyst, where they can recombine with the hydrogen ions and oxygen to form water. •The electrolyte is the proton exchange membrane(PEM). This specially treated material, which looks something like ordinary kitchen plastic wrap, only conducts positively charged ions. The membrane blocks electrons. •The catalyst is a special material that facilitates the reaction of oxygen and hydrogen. It is usually made of platinum powder very thinly coated onto carbon paper or cloth. The catalyst is rough and porous so that the maximum surface area of the platinum can be exposed to the hydrogen or oxygen. The platinum-coated side of the catalyst faces the PEM.

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What property of a liquid is characterized by its volatility?

QUESTION

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During the operation of the four-stroke, internal combustion engine, which strokes (if any) are in operation under the following sets of conditions? (a) Both the intake valve and the exhaust valve are closed. (b) Only one of these valves is open.

QUESTION

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What’s the difference between the “octane” that is given an octane rating of 100 and the octane of Table 7.3, with its rating of –20?

QUESTION

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What is the molecular formula of tetraethyllead?

QUESTION

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What automotive air pollutants are reduced by the use of catalytic converters? What pollutants are unaffected or perhaps increased?

QUESTION

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Even if the internal combustion engine were so efficient in burning gasoline that no catalytic converters were needed to protect the environment, its likely that “leaded” gasoline would no longer be available. Why?

QUESTION

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What facet of molecular structure other than the molecular weight or carbon content of its molecules affects the boiling point of an alkane?

QUESTION

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Suppose that one product of cracking a C9 alkane is:

CH3—CH2—CH2—CH2—CHCH2

What is the other hydrocarbon product?

QUESTION

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Name two products produced by the isomerization of pentane. What is produced through the aromatization of cyclohexane?

QUESTION