Alkanes vs. Alkenes - PowerPoint PPT Presentation

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Alkanes vs. Alkenes

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  1. Alkanes vs. Alkenes A Stinky Lab Turned into an Un-Stinky Power Point Presentation

  2. What do you think these words mean? • Homologous Series • Saturated Hydrocarbons • Unsaturated Hydrocarbons A group of compounds whose chemical formula increases by one carbon atom from one compound in the series to the next Ex: CH4, C2H6, C3H8… Hydrocarbons with all single bonds, any alkanes Hydrocarbons without all single bonds, any alkenes or alkynes

  3. Melting and Boiling Point • Look at the regular Chem text page 753 • What pattern do you see in boiling point as alkanes get more carbons? • What pattern do you see as molecules get less saturated? More carbons = higher boiling point Less saturated = more double bonds = lower boiling point… mostly

  4. Melting Point cont. Ethane< Butane < 1-Octene < Octane Put these in order of increasing melting point: Ethane Octane Butane 1-Octene

  5. Solubility Summary: Alkanes and Alkenes are both NOT soluble in water. Plus, they are less dense than water. Alkane Alkene Water with green food color

  6. Combustion Black Smoke Summary: Alkanes burn cleaner than Alkenes Alkene Alkane Blue Flame

  7. Alkane <-> Alkene • Alkane  Alkene is called cracking • Alkene  Alkane is called addition C3H8heat and Ni catalyst C3H6 + H2 C2H6 + H2 C2H8

  8. Identifying Alkanes/enes • Alkane + Halogen  Haloalkane (slow), substitution • Alkene + Halogen Haloalkane (fast) this is called addition C3H8 + Br2 C3H7Br + HBr C2H4 + Br2 C2H4Br2

  9. Bromine- Substitution and Addition Reactions Plain Br2 reference Alkene Alkene Alkane Alkane Plain Br2 reference • Summary: • Alkenes react quickly with Br2- addition • Alkanes react slowly + need UV light- substitution

  10. Quick Review • Alkanes and alkenes are ____ soluble in water • As # of C increases, melting point ____ • As saturation decreases, melting point ____ • Combustion of _____ is cleaner than _____ • Alkanes change into alkenes with _____ and _____ • Alkenes turn into alkanes with _____ • An ____ reacts quickly to decolorize Br2 NOT increases decreases alkanes alkenes heat Nickel catalyst hydrogen alkene

  11. We need fat in our diet Click here… • To… • Absorb shock, warmth, energy, move electrical/nerve currents, construct membranes, brain function, sex glands, hormone function • Cholesterol too • Can be from food, but our body makes all we need • Hormones, steroids, skin protectant, antioxidant • “Good cholesterol”= HDL, “Bad” = LDL

  12. Saturated Fats • Animal products + coconut and palm oils, peanuts, butter • Solids at room temperature and body temperature • Can stack up on each other because the structures are floppy, even form crystal structures (aggregate) • Insoluble in water • What they can do that’s bad: • Deposit + hardens arteries and increases blood pressure • Blood clots • Increase bad (LDL) cholesterol Avoid Them!

  13. Oils This shows the result when different butters and oils are combined with bromine. Which brand has the most saturated fat? Which has the least? So… Coconut oil is the worst and Wesson “best blend” is the best Most Unsat. Fat Most Sat Fat

  14. Unsaturated Fats • Have a very slight + and – charge, so they repel each other, keeping them fluid (liquid at room and body temperature) and unable to aggregate like saturated fats • Less stable (more likely to oxidize, turn rancid) than saturated fats • From 1 to 6 double bonds What they can do to your body… • Monounsaturated • Decrease bad cholesterol and increase good • Olive oil, canola oil, avocado, nuts, butter • Polyunsaturated • Decrease the bad • Omega fatty acids increase brain function • Cold water fish, almonds, walnuts, leafy veggies, flax, hemp, safflower, + brains, eyes, and testes of animals (which is why those parts were prized by primitive hunter-gatherer people)

  15. Cis vs. Trans A decent video

  16. Trans Fats Avoid Them! • Artificially created unsaturated fat, “partially hydrogenated” changes a cis double bond into a trans • Much more stable than unsaturated fats, but still just as cheap • Margarine, shortening, fried food, packaged food • Why are they bad? • They are solids • Clots and artery blockage • Cancers • Interfere with electrical currents

  17. FATS SATURATED Animal fats Tropical oils UNSATURATED Mono Avocados, Olives, Nuts Poly Flax, Hemp, Nuts, Fish, Sunflower, Canola Trans Margarine, Shortening + Packaged foods