ALKENES, POLYMERS AND ALCOHOLS
- Created by: Chelsey`Johnson
- Created on: 22-05-16 16:22
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- ALKENES, POLYMERS & ALCOHOLS
- ALKENES
- have a double carbon bond so are unsaturated
- general formula: CnH2n
- 1. Ethene C2H4 2.Propene C3H6 3.Butene C4H8
- isomers
- but-1-ene and but-2-ene are isomers -> 2 different structures as double bond can be in 2 different places
- two molecules with identical molecular formula but different structures
- HALOALKANES
- halogens react with alkenes to form haloalkanes
- addition reactions
- when double carbon bond splits and a halogen atom is aded to each of the carbons
- bromine + ethene -> dibromethene. C2H4 +Br2 -> C2H4Br2
- reaction between bromine and alkenes
- when shaken, orange bromine molecules react with the alkene to make the colourless dibromoalkAne
- ADDITION POLYMERISATION
- high pressure + catalyst + small molecules open up double bonds an polymerise to form polymers (very long saturated chains)
- monomer is added to the chain each time
- can be written as an equation using repeating units
- bond always comes out either side of the brackets
- monomer can be found by taking repeat unit and adding a double bond
- USES
- polyethene
- light structure -> packaging
- polychloroethene
- insulating electrical cables, clothes, pipes
- polyethene
- BIODEGRADABILITY
- don't degrade: unreactive to chemicals + bacteria
- can recycle (high cost) or incinerate (produces toxic fumes)
- polylactic acid (PLA) = biodegradable polymer ->special links are attacked by chemicals and absorb UV to break it down into its original monomers
- ALCOHOLS
- part of the homologous series
- remove hydrogen atom in an alkAne by an -OH
- 1. methanol 2.ethanol 3,propanol 4.butanol 5.pentanol
- CONDENSATION POLYMERS
- 2 different types of monomer = polymer chains
- produces a small molecule + polymer
- monomer + monomer -> condensation polymer + water
- DEHYDRATION OF ETHANOL TO ETHENE
- water molecule removes from the alcohol
- ethanol vapour passed over catalyst aluminium oxide (which provides large SA)
- C2H5OH -> C2H4 +H2O
- ALKENES
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