How to deduce the polymerisation reaction for any alkene
4 marks · NormalThe table below shows information about several polymers and their monomer units.
| Polymer | Monomer formula |
|---|---|
| poly(ethene) | CH2=CH2 |
| poly(chloroethene) | CH2=CHCl |
| poly(fluoroethene) | CH2=CHF |
State the feature common to all these monomers that enables them to undergo addition polymerisation.
Explain, with reference to the table, how the structure of the repeat unit of poly(chloroethene) is related to its monomer.
Name one use of poly(chloroethene).
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a.i) They all contain a carbon-carbon double bond (C=C).
(a.ii) In poly(chloroethene), the double bond in the monomer becomes a single bond in the repeat unit and the chlorine atom remains attached to the same carbon atom.
(a.iii) Used for pipes / electrical insulation / window frames / sheet flooring / any one correct use.
Also accept: States presence of C=C for i; explains loss of double bond and same side group for ii; any correct use for iii
Common mistakes: Saying 'single bond' instead of double bond; Not relating side group (Cl) in ii
Show mark scheme and worked solution
Marking points
B1 (a(i)) · 1 mark · States that the presence of a carbon-carbon double bond (C=C) allows addition polymerisation.
M1 (a(ii)) · 1 mark · Mentions the double bond is broken or reduced to a single bond in the polymerisation. (follow-through)
A1 (a(ii)) · 1 mark · States the chlorine atom stays attached to the same carbon atom in the repeat unit. (follow-through)
B2 (a(iii)) · 1 mark · Gives a correct use of poly(chloroethene) such as pipes, electrical insulation, or window frames.
Worked solution
a.i) All monomers contain a carbon-carbon double bond (C=C), which allows addition polymerisation.
a.ii) The double bond in the monomer becomes a single bond in the repeat unit. The chlorine atom in chloroethene remains attached to the same carbon as in the monomer.
a.iii) One use of poly(chloroethene) is for making pipes.