Condensation Polymerisation
Master Condensation Polymerisation for GCSE Chemistry with this free worksheet and full mark scheme — Higher-tier exam-style questions with worked answers for AQA, Edexcel and OCR. A separate (triple) Higher topic: two different monomers, each with two functional groups, join and release a small molecule such as water.
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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.
This is a Higher tier only topic, so there's no Foundation paper — only the Higher worksheet and mark scheme below.
Topic overview
Condensation polymerisation involves monomers with two functional groups, and it produces a small molecule such as water alongside the polymer. This is a Triple and Higher-only topic.
The simplest case involves two different monomers, each with two of the same functional group. When a diol reacts with a dicarboxylic acid, ester links form between them, producing a polyester and water.
The key contrast with addition polymerisation is that two products are formed rather than one. Addition needs one type of unsaturated monomer and gives only the polymer; condensation needs monomers with two functional groups and gives the polymer plus a small molecule.
Revision notes
The reaction
Monomers containing two functional groups react together.
When a diol reacts with a dicarboxylic acid, an ester link forms between them and a molecule of water is released each time. The result is a polyester.
Two products
Condensation polymerisation always produces a small molecule as well as the polymer, usually water.
This is the defining difference from addition polymerisation, which produces the polymer only.
Comparing the two types
Addition: one monomer type, unsaturated with a double bond, one product.
Condensation: monomers with two functional groups each, two products. Being able to state this comparison clearly is what most questions require.
Key points
- Condensation polymerisation produces a small molecule too.
- Monomers have two functional groups.
- A diol and a dicarboxylic acid form a polyester.
- Ester links join the monomers.
- Water is usually the small molecule released.
- Addition polymerisation gives only one product.
Worked examples
Example 1
State the two products of condensation polymerisation. [2 marks]
Model answer
The polymer (1 mark) and a small molecule, usually water (1 mark).
Example 2
State two differences between addition and condensation polymerisation. [2 marks]
Model answer
Addition polymerisation uses unsaturated monomers with a carbon-carbon double bond, whereas condensation uses monomers with two functional groups (1 mark). Addition produces only the polymer, whereas condensation also produces a small molecule such as water (1 mark).
Example 3
Name the type of link formed when a diol reacts with a dicarboxylic acid. [1 mark]
Model answer
An ester link (1 mark).
Common mistakes
Saying only the polymer is formed.
A small molecule such as water is always also produced.
Using unsaturated monomers.
Condensation monomers have two functional groups, not double bonds.
Confusing the two types of polymerisation.
Learn the comparison as a pair of contrasts.
Forgetting to name the ester link.
It is the link formed in a polyester and is often worth a mark.
Exam tips
- Always state that two products are formed.
- Learn the addition versus condensation comparison as a set.
- Name the ester link when describing a polyester.
- Remember this is a Triple and Higher-only topic.
Key terms
- Condensation polymerisation
- Polymerisation producing a small molecule as well as the polymer.
- Diol
- A monomer with two –OH groups.
- Dicarboxylic acid
- A monomer with two –COOH groups.
- Ester link
- The bond joining monomers in a polyester.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.