Edexcel Jan 2014 (IAL) Paper 1 Q20

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20 This question is about the chemistry of alkenes, which are unsaturated hydrocarbons. (a) State what is meant by the term unsaturated as applied to a hydrocarbon. (1)(b) An organic compound, X, is an unsaturated hydrocarbon with molecular formula C4H8. (i) Draw the displayed formulae and give the names of two unbranched molecules with molecular formula C4H8 which are E/Z isomers. Isomer 1 Isomer 2 Name: Name: (ii) Both isomers react with a solution of acidified aqueous potassium manganate(VII). State the colour change that you would observe when this reaction is carried out. (3) (1) Fromto20 *P42986A02024*<br /> (iii) Draw the structure of the organic product of this reaction with either one of these isomers. (iv) Compounds such as C4H8 are formed when fractions of crude oil are cracked. State what is meant by the term cracking when applied to processing a fraction obtained from crude oil. (1) (1)(v) Write an equation to show the cracking of the hydrocarbon octane into C4H8 and a saturated hydrocarbon as the only products. (1) *P42986A02124* 21 Turn over<br /> (c) Another alkene is propene, C3H6. Describe the mechanism for the addition reaction of propene with bromine, Br2, to form C3H6Br2. In your answer you should include: (cid:404) (cid:404) (cid:404) the name for the type of addition which occurs the name of the product the mechanism using curly arrows to show the movement of electron pairs. (5) Type of additionName of productMechanism 22 *P42986A02224*<br /> (d) Propene can polymerize to form poly(propene). (i) State, with a reason, the atom economy for this reaction. (1)(ii) Draw a section of this polymer, showing two repeat units. (iii) Poly(propene) is used to make synthetic fibres which are extremely light and act as good insulators. Comment on the sustainability of this use of poly(propene). (1) (1)(Total for Question 20 = 16 marks) TOTAL FOR SECTION B = 60 MARKS TOTAL FOR PAPER = 80 MARKS *P42986A02324* 23<br />

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