Alkanes and alkyl halides The Saturated Hydrocarbons The
Alkanes! (and alkyl halides) The Saturated Hydrocarbons
The Saturated HC’s-alkanes • Have only single bonds • Also called the “paraffin compds” – Paraffin is an older term meaning “of little activity” • Alkanes are also saturated-meaning? • Completely full of stuff – Diaper demo
Fossil Fuels • • • These are dead plants/animals that decay into a mixture of solid, liquid, and gaseous HC’s Natural gas and petroleum are fossil fuels-usually found together What are they good for? – – Sources of NRG (fireplace story) Informative video with relaxing hypnotizing background music-10 min http: //videos. howstuffworks. com/hsw/17472 -power-up-fossil-fuels-video. htm Making plastics, drugs, synthetic fibers • • Putting old tires in pavement video 1. 3 min http: //videos. howstuffworks. com/hsw/18903 -enviro-tacklebox-phoenix-and-asphalt-rubber-video. htm • Asphalt Rockets – – Tim’s movie here http: //timpickens. com/ Buzz Aldin and Snoop Dog video http: //www. youtube. com/watch? v=Hc. Ue. GRp. Pzgw The making of the video – http: //www. youtube. com/watch? v=la 4 u. PBqg. Qlc
Fossil fuels cont’d • Coal – – – Coke-artificially made pure coal Anthracite-hard coal-purest in nature Bituminous-contains sulfur (glove story) Lignite-brown coal, smoky flame Peat-partially decomposed organic matter • Dirty Jobs Video on coal mining 5 min – http: //videos. howstuffworks. com/discovery/30930 -dirtyjobs-coal-mining-video. htm • Or maybe this one’s better 5 min – http: //videos. howstuffworks. com/science-channel/34261 how-do-they-do-it-coal-mining-video. htm
Life-saving canaries • Don’t write all this • Coal mines are breeding grounds for methane and carbon monoxide, which are hazardous to human health, as well as conducive to deadly explosions. Before methane or carbon monoxide detectors existed, miners brought canaries down into coal mines with them. If a canary died, it was a sign of the presence of noxious gases and meant it was time to high tail it out of there.
Preparation of Alkanes • Exodus story • *Israel has no oil! • Alkanes are so abundant in nature that there’s no need to make them in lab • Instead they are collected/purified for use
Petroleum Refining! • Petroleum in its(*) natural state is worthless • It can be made into useful products by refining • See residue • Refining videos 10 min • http: //www. youtube. com/watch? v=jk 0 Wrt. A 8_T 8
• The 1 st 10 alkanes • represented by the formula Cn. H 2 n+2 See board • Know the 1 st 10 alkanes-name, molecular formula, and structural formula-also recognize expanded and condensed forms • Q: Why are none of these alkanes solids? • A: b/c they have very low freezing/melting pts-most are liquids or gases • Q: which is more gaseous-ethane or pentane? • Bpts and mpts increase with # of C’s
N and Iso Alkanes • alkanes that form a continuous unbranched chain are called normal or n-alkanes • Give exs • iso-alkanes have one branched C (on the second C) • 4 kinds of carbons – – Primary, secondary, tertiary, quaternary Normal alkanes have only primary and 2 ndy C’s Iso-alkanes have at least one 3 rd or 4 th degree C Ex: isopropyl acohol
Naming Alkanes • IUPAC naming rules! – Find longest continuous C chain, give it a base name (ex: propane, pentane) – Identify side groups • halogens-chloro, bromo, iodo, fluoro • alkyl groups-methyl, propyl – Assign prefixes, alphabetize, use lowest #’s • Naming cycloalkanes
Chemical Reactions of Alkanes • Oxidation=combustion=burning • General pattern for oxidation reactions is: • HC + oxygen carbon dioxide + water + heat • EX: methane + oxygen carbon dioxide + HOH
Exs of Combustion Rxns • CH 4 + 2 O 2 CO 2 + 2 H 2 O • C 3 H 8 + 5 O 2 3 CO 2 + 4 H 2 O • http: //videos. howstuffworks. com/discovery/ 29392 -assignment-discovery-combustionvideo. htm 2 min lady w/boring voice
• The ratio of O to C is very impt • W/out enough O 2, you get CO instead of CO 2 • Ex: car engine • So why would that be bad? 3 min video – http: //www. youtube. com/watch? v=lcht. RTDs. H SM
What CO does in the body • Blood loves CO 200 x> than O 2 • Blood exposed to CO is less able to pick up and distribute O 2 • Symptoms of CO poisoning: – – Headaches Nausea Death http: //www. youtube. com/watch? v=Qfu. Zu. Wp. O 7 KY 9 min • CO poisoning stories – Skyline Acres – Prostitutes
• The 2 nd Chemical Rxn of Alkanes • 2. Substitution-sometimes you can sub a halogen for a hydrogen in an alkane making an alkyl halide • Ex rxn on board • Alkyl halides are very reactive • Represented by "RX" (not "rxn")
• Specific alkyl halides: – Bromomethane or methyl bromide • Berries from the west coast are made by forcing CH 3 Br into the soil • ground is covered w/plastic to keep gas from escaping, then crops are planted • Huge berries are b/c CH 3 Br kills worms, fungi, dogs, cats, & Mexicans • Mexicans? !
• The govt plans to ban methyl bromide • Why? – b/c it’s an ozone depletor • Many crops depend on CH 3 Br • It’s also used in termite fumigation-houses covered in plastic-kills termites, rats, and vagrants • Alternatives to methyl bromide – http: //www. youtube. com/watch? v=TOe 8 NJYQ l. AE
• “Chloromethanes” • CH 3 Cl-chloromethane-a good liquid solvent • CH 2 Cl 2 -dichloromethane-A good refrigerant • CHCl 3 -trichloromethane (chloroform) • Was once used in non-alcoholic pediatric cough syrups • CCl 4 -carbon tetrachloride • Excellent spot remover for dry cleaning, but carcinogenic, killed Chinese laundry workers
• • others CF 2 Cl 2 Dichlorodifluoromethane-Freon A refrigerant that’s completely unreactive Heat causes it to vaporize-goes into condenser, is liquified and reused. – Olan story • It’s also a good propellant b/c it’s unreactive • How ac’s work- video http: //videos. howstuffworks. com/howstuffworks/1 -how-air -conditioners-work-video. htm • Freon escapes into the stratosphere where it’s zapped w/UV light and removes Ozone (O 3) • O 3 is like a screen that protects us from UV light-too much UV light can cause cancer
• Chloroethane-see board • Used as a cold spray to deaden skin before injections • Used by athletic trainers-deadens pain by cooling when players are hurt • also used to ripen fruit • In Israel, nanner trees are covered w/bags to help the nanners ripen faster
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