2.1.3 Alkenes 0.0 / 5 ? ChemistryGreen ChemistryASOCR Created by: upsidedown1004Created on: 31-05-16 17:31 What are alkenes? unsaturated hydrocarbons 1 of 23 What does an alkene double bond consist of? one sigma and one pi bond 2 of 23 What is a pi bond? an exposed area with a high electron density 3 of 23 How does the pi bond form? sideways overlap of 2 p-orbials on each C atom // forms pi bond above and below the plane 4 of 23 describe the shape and structure of alkenes trigonal planar // 120 5 of 23 How do you form an alkane from an alkene? hydrogenation// addition// ticket catalyst and hydrogen gas 6 of 23 how do you form a dihalogenoalkane from an alkene? electrophilic addition// halogenation // heterolytic fission 7 of 23 what is an electrophile? an electron pair donor 8 of 23 describe the separation and recycling of waste polymers sorted into different types of polymers // recycled by melting and remoddling 9 of 23 How are waste polymers used as feedstock for cracking? allows new production of plastics/ chemicals 10 of 23 How are waste polymers used in energy production? incinerated // heat produced used to generate electricity// combustion of halogenated alkenes can lead to toxic waste 11 of 23 What is polyethene used for? plastic bags, buckets, bottles // flexible easily moulded chemical proof low density 12 of 23 what is polypropene used for? utensils, containers, fibres // stiff 13 of 23 what is a polymer? long molecular chain built from monomer units 14 of 23 why are polyalkenes unreactive? strong C-H and C-C bonds 15 of 23 what is the industrial importance of alkenes? formation of useful polymers// manufacture of margarine 16 of 23 how is margarine manufactured? hydrogenation pf unsaturated veg oils using H and nickel catalyst // double bonds broken to lower BP 17 of 23 What are the ways in which waste polymers are processed? seperation and recycling // feedstock for cracking // combustion for energy production 18 of 23 How is the environmental damage from waste polymers being minimised? removal of toxic waste products post-combustion // development of biodegradable and compostable polymers from isoprene/ maze/ starch 19 of 23 How do you test for unsaturation? bromine dissolves in water to form orange solution // added to alkane it remains orange // added to alkene it goes colurless 20 of 23 What happens if an unsymmetrical alkene undergoes halogenation? can lead to formation of two isometric products 21 of 23 Describe the production of alcohols mainly done industrially due to high pressure // high atom economy as no waste products 22 of 23 How are addition polymers made? polymerisation of monomer to polymer 23 of 23
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