7.12 Condensation polymers
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What small molecule is usually released when a polyester forms?
Choose one answer.
Correct Not quite: the answer is Water
Mark scheme
A
Model answer
A: water is lost at each ester link.
Explain why the monomers in condensation polymerisation must have two functional groups.
Mark scheme
- one group reacts at each end (1)
- so the chain can keep growing in both directions / form a long chain (1)
Model answer
Each monomer must be able to react at both ends, so that it can link to two other monomers and the chain can keep growing.
Name the two types of monomer used to make a polyester.
Mark scheme
- a diol (1)
- a dicarboxylic acid (1)
Model answer
A diol and a dicarboxylic acid.
Give two differences between addition and condensation polymerisation.
Mark scheme
any two from:
- addition: one product; condensation: two products / water lost (1)
- addition: monomers have C=C; condensation: monomers have two functional groups (1)
- addition: one type of monomer; condensation: usually two (1)
Model answer
Addition polymerisation uses monomers with a C=C bond and gives only the polymer; condensation uses monomers with two functional groups and also produces water.
How many water molecules are produced when n molecules of a diol react with n molecules of a dicarboxylic acid?
Mark scheme
- 2n (1)
Model answer
2n water molecules, one for each link formed.
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