ACSBR Addition Polymerisation - Lesson Package

SYLLABUS RELEVANCE & TEXTBOOK CHAPTERS O-LEVEL PURE (5072) /checkbld/checkbld /checkbld/checkbld Chapter 25 O-LEVEL SCIENCE (5116) /checkbld/checkbld /checkbld/checkbld Chapter 20 Topic 20D: Answers Addition Polymerisation N-LEVEL SCIENCE (5155) /xmarkbld/xmarkbld /xmarkbld/xmarkbld Lesson Package & Accompanying Slides Designed by Alex Lee (2011) Last Modified by Alex Lee (2011) ANGLO-CHINESE SCHOOL (BARKER ROAD) 169 TOPIC 20D: ADDITION POLYMERISATION 1. Addition Polymerisation: Polyethene Under extreme pressure (about 1000 atm), ethene molecules can undergo addition reactions with itself. This is known as addition polymerisation . The product of this reaction is polyethene . Polyethene is commonly found in the household, made into ……………………………… or ……………………………… . ‘Polymerisation ’ refers to ……………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………………………………………… . ‘ Addition polymerisation ’ refers to ………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………………………………………… . In the above diagram, we had represent the polymer as a segment showing three repeating units. To represent the polymer in its entirety, we should use brackets as shown: C C H H H H  → ressurep high C C H H H H ethene (monomer) polyethene (polymer) n n n represents a very large integer C C H H H H C C H H H H C C H H H H + +  → ressurep high C C H H H H C C H H H H C C H H H H C C H H H H C C H H H H C C H H H H the double bonds are first broken the molecules then bond on both sides ethene (monomer) polyethene (polymer) to form a macromolecule (known as a polymer). a reaction in which many small organic molecules combine organic molecules combine to form a macromolecule as the only product. a reaction in which many small unsaturated plastic bags clingfilm

ANGLO-CHINESE SCHOOL (BARKER ROAD) 170 TOPIC 20D: ADDITION POLYMERISATION We only consider a molecule to be a polymer when an uncountable number of monomers have been joined together. If only two or three monomers have been joined, we do not consider it to be a polymer. Since the number of monomers (or repeating units) is uncountable, we simply represent this by the letter ‘ n’. We have to be careful of the terminology: “MONOMER” The small organic molecule before polymerisation takes place, i.e. ethene. In the case of addition polymerisation, the C=C bond will still be present. “POLYMER” The macromolecule formed after polymerisation takes place; brackets and ‘n’ are used to represent a very large number of repeating units. THREE “REPEATING UNITS” Represents a segment of the polymer chain; do not draw brackets since this represents a definite number of repeating units. However, ‘continuation lines’ and ‘continuation dots’ must still be shown clearly on ea