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Welcome Back!
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Topics for Today Gasoline additives (MTBE, ethanol, and oxygenates) Part II!
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Readings for Today 4.10 Newer fuels and other sources
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Topics for Today The “other” part of crude oil Uses of polyethylene
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Readings for Today 9.1 Polymers: The long, long chain 9.2 The “Big Six” 9.3 Addition polymerization 9.4 Polyethylene
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Topics for Wednesday Where Do We Find Other Addition Polymers? PETE (A Polyester)!
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Readings for Today 9.2 The “Big Six” 9.3 Addition polymerization 9.5 Condensation Polymers
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Topics for Today Gasoline additives (MTBE, ethanol, and oxygenates) Part II!
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What’s good about using ethanol? 1) Reduced CO emissions * 2) Less direct impact if spilled
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Problems with ethanol?
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Air Pollution Implications CO (tons / day) NO x (tons / day) VOCs (tons / day) Emissions compared to today -237.5+ 10+ 25 - means decreased emission + means increased emission
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Problems with ethanol? 1) Air pollution compromise
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Problems with ethanol? 1) Air pollution compromise 2) We eat corn!
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What is ethanol currently made from?
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Reducing supply of sweet corn! Increased prices of corn Over the past year, corn prices have doubled!
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Problems with ethanol? 1) Air pollution compromise 3) Energy requirement … 2) We eat corn!
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For gasoline, we use 6 gallons. Compared to the energy we get out of the fuel… We would have to use 75 gallons of ethanol to make 100 gallons
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For equal volumes of ethanol and gasoline Which contains more energy? This leads to reduced gas mileage…
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Problems with ethanol? 1) Air pollution compromise 3) Energy requirement … 4) More corrosive than gasoline 2) We eat corn!
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Cannot use the same pipelines used to transport gasoline
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Why do we use fuel additives? 1) To increase the octane number 2) To make a cleaner fuel
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Oxygenate #2 CH 3 | CH 3 – O – C – CH 3 | CH 3 An ether MTBE
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Alcohol R – O – H Ether R – O – R R = some hydrocarbon group (methyl, ethyl, etc…)
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Oxygenate #2 CH 3 | CH 3 – O – C – CH 3 | CH 3 An ether MTBE Octane rating = 116
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Oxygenate #2 CH 3 | CH 3 – O – C – CH 3 | CH 3 An ether MTBE
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Oxygenates M = methyl T = “tert” or tertiary B = butyl E = ether CH 3 | CH 3 – O – C – CH 3 | CH 3 KNOW
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Review: Where have we seen an ether before? CH 3 – O – CH 3 Dimethyl ether
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CH 3 – O – CH 2 – CH 3 Name? ethyl methyl ether Isomers?
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Why can MTBE be added at the refinery?
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CH 3 | CH 3 – O – C – CH 3 | CH 3 H H | | H – C – C – OH | | H H Which is more polar? Which will better dissolve in gasoline?
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MTBE Replaced TEL in 1979 ~11% by volume Not used much anymore… Why not?
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Leaks into the ground water… Health effects uncertain Distinct odor at very low levels How does it leak into the groundwater?
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Underground Storage Tanks…
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Prior to MTBE Remove leaking tank, … Spill some gasoline. (insoluble in groundwater) Gasoline degrades quickly.
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After MTBE Remove leaking tank, … Spill some gasoline. (insoluble in groundwater) Gasoline degrades quickly. But MTBE persists in the water.
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So far, we have only been focusing on making fuel from crude oil…
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What else can we do with crude oil?
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A closer look…
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Where do we find plastics?
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Everywhere! !
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Just the beginning! Assignment #4 due Wed the 18 th !
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Chemically speaking, what are plastics?
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Polymers!! Really, really big molecules made up of smaller ones
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Polymers!! The smaller molecules are called monomers.
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Where have we seen a polymer in Chem 108?
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Cellulose A chain (polymer) of glucose molecules. Glucose: C 6 H 12 O 6
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Cellulose The monomer is glucose! Other natural polymers?
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Spider Webs and Silk
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Other natural polymers? Wool
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Other natural polymers? Fur and Hair
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Beaks Feathers Claws Fingernails Other natural polymers?
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Proteins! Other natural polymers? Starch!
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Some synthetic (manmade) polymers?
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Teflon Kevlar Nylon Gore-Tex Polyester Rayon And many, many more! Other synthetic polymers
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Polyethylene Polypropylene Polyvinyl Chloride Polystyrene Other synthetic polymers
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Fig.09.01a Table 9.1 (p. 401)
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Fig.09.01b Table 9.1 (p. 401)
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Polyethylene Table 9.1 (p. 401)
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How do we make PE?
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Polyethylene Ethylene = double bond… Where’d the double bond go?
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Monomer for PE CC HH H H Name? Ethene (or ethylene) C 2 H 4 How do we get PE from ethene?
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Free Radical Polymerization! 1. Initiation Reaction CC H H H H R.R. +
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CC H H H H R.R. +.. CC.C. HH HH R Free Radical EthyleneNew Radical
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Free Radical Polymerization! 1. Initiation Reaction CC H H H H R.R. +.. CC.C. HH HH R Free Radical EthyleneNew Radical What happens to a nearby ethylene molecule?
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CC.C. HH HH.. R New Radical CC H H H H +.. Ethylene CC HH HH.. R C HH HH C.C. Newer Radical Then what happens?
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Figure 9.5, page 407
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Polyethylene This will go on for 1000s of units… How else can we write this?
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Polyethylene Repeating Unit
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Polyethylene CC HH HH n Easier way to write PE! “n” can be in the 1000s and higher OR CH 2 n
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Polyethylene formation [ ]n]n –CH 2 –CH 2 – n C = C H HH H R·R·
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Addition Polymerization!! Initiated by a free radical. No by-products! http://chemincontext.eppg.com/chapter9/cic_interface9.swf Animation !
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PE comes in more than 1 form!
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Types of Polyethylene Figure 9.7 (p. 409)
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Why does HDPE have a slightly higher density? Different chemical structures = different chemical properties… Linear ~0.96 g / mL Branched ~0.93 g / mL
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