Ethene presentation

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Ethene presentation

  1. 1. Ethene
  2. 2. Properties <ul><li>Structural, Chemical and Physical </li></ul><ul><li>General formula C n H 2n </li></ul><ul><li>Non-polar </li></ul><ul><li>Planar </li></ul><ul><li>Double bond (alkene), reactive </li></ul><ul><li>Molecule held together by dispersion forces </li></ul><ul><li>Flammable </li></ul><ul><li>Sweet odor </li></ul><ul><li>Colourless gas </li></ul><ul><li>Boiling point -104 o C </li></ul><ul><li>Melting point -169 o C </li></ul><ul><li>Molecular Weight 28.08 </li></ul><ul><li>Heat of fusion 119.5 kJ/kg </li></ul><ul><li>Heat of Combustion 47.183 MJ/kg </li></ul><ul><li>Enthalpy of Formation 52.32 kJ/mol </li></ul>
  3. 3. Reactions <ul><li>Since ethene is an alkene, it follows some characteristic reactions of alkenes. </li></ul><ul><li>Such reactions include: </li></ul><ul><li>Addition reactions </li></ul><ul><li>– With water, halogens, hydrogen halides, hydrogen </li></ul><ul><li>- Halogenation and polymerization are both addition reactions </li></ul><ul><li>Oxidation reactions </li></ul><ul><li>- When using potassium permanganate as the oxidant, products of reaction are dependent on the pH condition of the KMnO 4 </li></ul><ul><li>- Acidic = purple to colourless </li></ul><ul><li>- Basic/neutral = purple to dark green with brown precipitate </li></ul><ul><li>Combustion reaction </li></ul><ul><li>- The usual. Reacts with oxygen, carbon dioxide and water vapour formed. </li></ul>
  4. 4. How is ethene manufactured? <ul><li>Two sources: </li></ul><ul><li>- Natural Gas </li></ul><ul><li>- Crude Oil </li></ul><ul><li>Thermal/Steam cracking </li></ul><ul><li>- Process: </li></ul><ul><li>1. Feedstock and steam fed into coiled tube in furnance, 750 – 900 o C. </li></ul><ul><li>2. Then passed into cooler at -100 o C. Gases then separated by distillation. </li></ul>
  5. 5. … and continuing <ul><li>An example of a typical cracking reaction: Ethane forms ethene through the cracking procedure. </li></ul><ul><li>C2H6 (g)  C2H4 (g) + H2 (g) ∆H = + 138 KJ/mol </li></ul><ul><li>Maximum yield at: </li></ul><ul><li>- High temperature </li></ul><ul><li>- Pressure just below the atmosphere pressure </li></ul><ul><li>Other methods of manufacture: </li></ul><ul><li>Dehydration of ethanol </li></ul><ul><li>- Presence of a catalyst (sulfuric acid, aluminium oxide, zeolite catalyst) </li></ul><ul><li>Using cellulose as a raw material </li></ul><ul><li>- Too costly. In every singly way imaginable. </li></ul>
  6. 6. Hazards of ethene <ul><li>Escapes into the environment by: </li></ul><ul><li>- From its production </li></ul><ul><li>- Cigarette smoke </li></ul><ul><li>- Waste incineration </li></ul><ul><li>- Vehicle wastes </li></ul><ul><li>Hazards of use </li></ul><ul><li>- Gas state – Especially highly flammable and explosive </li></ul><ul><li>- Prolonged exposure can harm the brain, if inhaled </li></ul><ul><li>- Liquid state – Very cold, risk of frostbite </li></ul><ul><li>Sniffing ethene result in: </li></ul><ul><li>- light-headedness, dizziness, unconsciousness, and suffocation </li></ul>Kaboom?
  7. 7. Environmental Hazards <ul><li>Low concentrations – No negative harm </li></ul><ul><li>High concentrations – Affect growth of plant life. </li></ul><ul><li>Ethene = Ripening agent </li></ul><ul><li>Causes – Fruit to ripen quickly </li></ul><ul><li>- Leaves to fall off more quickly </li></ul><ul><li>- Stunted growth </li></ul><ul><li>Disposing: </li></ul><ul><li>- Via burning preferable to releasing into atmosphere </li></ul>
  8. 8. Industrial Uses <ul><li>Fruits and Plastic </li></ul><ul><li>Fruits </li></ul><ul><li>- Ethene produced by fruits </li></ul><ul><li>- Allows the fruit to ripen </li></ul><ul><li>- Rate of ripening can be control by controlling ethene levels </li></ul>
  9. 9. Polymerization <ul><li>Polymerization = reaction where monomers join together to form a large chain molecule </li></ul><ul><li>= formation of plastic </li></ul><ul><li>Monomers such as ethene, vinyl chloride and styrene polymerize to form polymers which can be used for many applications. </li></ul><ul><li>Polyethene – Used in plastics </li></ul><ul><li>Polyvinyl chloride (PVC) – thermoplastic </li></ul><ul><li>- additives sometimes added </li></ul><ul><li>- used in wire coatings, packaging and </li></ul><ul><li>many more </li></ul><ul><li>Polystyrene – hard </li></ul><ul><li>- transparent </li></ul><ul><li>- found in food cups and plastic containers etc </li></ul>
  10. 10. More more more and more uses <ul><li>As antifreeze </li></ul><ul><li>- Main component - ethylene glycol </li></ul><ul><li>- Aqueous ethylene glycol used in car radiators </li></ul><ul><li>Formation of ethanol </li></ul><ul><li>- Ethene reacts with water in the presence of a catalyst to form ethanol </li></ul><ul><li>- Ethanol then used as solvent in : </li></ul><ul><li>- Inks </li></ul><ul><li>- Cosmetics </li></ul><ul><li>- Pharmaceuticals </li></ul>
  11. 11. Thank you (:

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