AC 3.1 Draw and explain the mechanism for an electrophilic addition reaction of an alkene. AC 3.2 Explain addition polymerisation. a) Explain why alkenes are described as being unsaturated hydrocarbons. b) Use a diagram to illustrate how a carbon-carbon double bond forms. c) Draw and explain the mechanism for the reaction between ethene and hydrogen bromide(HBr). In your explanation include and define the terms 'electrophile' and 'carbocation'. Usecurly arrows to show electron movements and indicate any partial charges. 2. Hydrogen bromide reacts with propene to form either 1-bromopropane or 2-bromopropane.Explain why 2-bromopropane is the major product. 3. Explain how the reaction with bromine can be used to test for an alkene. Include the mechanism for the reaction between hex-1-ene and bromine in your answer. a) Describe the process of addition polymerisation. b) Show the repeating unit of the polymer that is formed from the addition polymerisation of chloroethene monomers. Name and give at least one use for this polymer.

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