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Making Polymers – Revision Pack (C1) Hydrocarbons: A hydrocarbon is a compound made up of hydrogen and carbon atoms ONLY. Alkanes are hydrocarbons that have single covalent bond ONLY; you can work out how many carbon atoms there should be in an alkane if you know how many hydrogen atoms there are and vice-versa using this formula: CnH 2n+2 (The number of hydrogen atoms is twice the number of carbon atoms plus 2) Name of alkane Methane Chemical formula CH 4 Ethane C2H6 Propane C3H8 Butane C 4 H 10 Displayed formula Alkenes are hydrocarbons that have a double covalent bond between carbon atoms (this will look like this is chemical formula: C=C). Double bonds involve the sharing of two pairs of electrons. You can also work out how many carbon atoms there should be in an alkene if you know how many hydrogen atoms there are and vice-versa using this formula: C n H 2n (The number of hydrogen atoms is twice the number of carbon atoms) Name of alkene Ethene Chemical formula C4H4 Propene C3H6 Butene C4H8 Displayed formula Making Polymers – Revision Pack (C1) You can test for alkene presence using bromine water; once added to the solution, the bromine water which is orange, should turn colourless. This happens because the alkene and the bromine form a new compound by an addition reaction called a dibromo compound which is colourless. A saturated compound is one that only has single covalent bonds between carbon atoms; alkanes are examples of saturated compounds. An unsaturated compound is one that has at least one double covalent bond between carbon atoms. Alkenes are examples of unsaturated compounds. Polymerisation: Additional polymerisation is the process where lots of monomer alkene monomers react to give a polymer. The reaction needs a high temperature and a catalyst. The displayed formula for an ethene monomer is left. In polymerisation the double bond is broken and each of the two carbon atoms forms a new bond – a long chain is formed. This is poly(ethene) which is to the right. The ‘n’ represents how many times the pattern should be repeated. Additional polymerisation involves the reaction of many unsaturated monomer molecules to form a saturated polymer. You should be able to draw the displayed formula of a polymer when given the monomer and vice-versa. Another example of polymerisation is that of propene: The monomer is unsaturated and a hydrocarbon. During polymerisation, the double bond breaks and each of the two carbon atoms forms a new bond which can be bonded to more monomers. TIP – look for the pattern of repetition every two carbon atoms. Making Polymers – Revision Pack (C1) Past Papers: PPQ(1): Making Polymers – Revision Pack (C1) PPQ(2): PPQ(3): Making Polymers – Revision Pack (C1) PPQ(4): PPQ(5): Continued on next page... Making Polymers – Revision Pack (C1) Making Polymers – Revision Pack (C1) PPQ(6): Making Polymers – Revision Pack (C1) PPQ(7): Making Polymers – Revision Pack (C1) Mark Schemes: PPQ(1): PPQ(2): Making Polymers – Revision Pack (C1) PPQ(3): PPQ(4): PPQ(5): PPQ(6): On next page... Making Polymers – Revision Pack (C1) PPQ(7):