What harris doesn't know

• what is hydrogenation of alkenes? conditions

  • alkene + H2 forming an alkane
  • nickel catalyst at 423 K
  • all C=C double bonds react this way and break and attach to H
• what is the halogenation of an alkane? what is a common example in chemistry?


  Rapid addition forming haloalkane

  • requires room temp

  can be used to identify alkene- will causes orange colour of iodine to disappear
• what happens during hydration of am alkene and what conditions does it require?

  • requires steam h20 (g) and a phosphoric acid catalyst (H3PO4)
  • is used in industry to produce ethanol from ethene
  • two possible products

  
• mechanism for electrophilic addition between but2ene and hydrogen bromide?

  .

  
• what are polymers?

  large molecules formed from thousands of repeating units called monomers
• what is addition polymerisation?

  when unsaturated alkenes are polymerised at high temp and pressure with a catalyst to produce long saturated chains with no double bonds
• what are some uses of poly(ethene)?

  most commonly used polymers: straws, toys, supermarket bags, shampoo bottlew

  low density and high density version

  • HDPE- linear chains= strength
  • LDPE- branched chains= little strength but flexible
• What is the use of poly(chloroethane) and what is it more commonly known as?

  Use: Insulation, packaging and to make a polymer that is flexible or rigid Common Name: PVC (Polyvinyl chloride)
• how to prevent the waste polymers harming the environment?

  • sorting discarded polymers by type allowing them to be chopped into flakes, washed, dried, melted and cut into pellets that can be used again
  • dissolving PVC using solvents and collecting high grade PVC from the precipitates to be used again. This is instead of burning them due to lack of space in landfill which releases hydrogen chloride= pollutant and hazardous
  • polymers made of petroleum or natural gas= high energy value= hard to recycle= incinerated to produce heat= steam generate—> drives turbines to produce electricity
• what is feedstock recycling?

  Chemical and thermal processes that turn even unsourced and unwashed polymers back into their monomers gases or oils to be turned back into new polymers
• What is biodegradable polymers made up of and used for?

  • Made up of starch or cellulose and contains additives that alter their structure which allows them to be broken down by micro organisms into water, co2 and biological compounds
  • eg compostable polymers= degrade and leave no visible trace or toxic residues
  • Can be used in supermarket bags, plates and cups and packaging
• What are photodegradable polymers?

  Polymers that contain bonds that are weakened by absorbing light to start the degradation process

  this can also be done by adding light absorbing additives