What is the monomer used to make poly(ethene)?

ethene. The polymer is named after its monomer.

What must a monomer have to take part in addition polymerisation?

a carbon–carbon double bond. The double bond opens so the monomers can link up.

Which small molecule is usually lost in condensation polymerisation?

water. One is lost each time two monomers join.

What type of polymer is nylon?

a polyamide. It is made by condensation polymerisation.

Why do plastics cause pollution?

They are not biodegradable. Microbes cannot break most of them down.

Proteins are polymers of what?

amino acids. Amino acids join by condensation to make proteins.

Polymers and plastics · Cambridge IGCSE Chemistry (9

In plain words

A polymer is a very long molecule made by joining thousands of small ones, like a chain of paper clips. The small molecules are monomers. Plastics are polymers, and so are the proteins in your body.

Three things to know

Addition polymerisation: alkene monomers join when their double bonds open, and the polymer is the only product. Ethene makes poly(ethene).
Condensation polymerisation: two kinds of monomer join, and a small molecule such as water is lost each time. Polyesters and polyamides (nylon) are made this way. Proteins are natural polyamides, made from amino acids.
Most plastics do not break down, so they fill landfill sites and pile up in the oceans. Burning them can give off toxic gases.

Worked example

Name the polymer made from the monomer propene, and the type of polymerisation.

Put "poly" in front and the monomer's name in brackets: poly(propene).
Propene is an alkene, with a C=C double bond that opens up.
Poly(propene), by addition polymerisation.

Tips and tricks

To draw a repeat unit: change the double bond to a single bond, and put a bond out of each side through brackets.
Addition: one product only. Condensation: the polymer plus a small molecule, usually water.

6 questions, about 2 minutes.

It lands in your notebook with its questions as flashcards.

Polymers and plastics: 6 questions and answers

These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.

What is the monomer used to make poly(ethene)?
- ethane
- ethene (the answer)
- ethanol
- methane
The polymer is named after its monomer.
What must a monomer have to take part in addition polymerisation?
- an –OH group
- a carbon–carbon double bond (the answer)
- an ionic bond
- a ring of atoms
The double bond opens so the monomers can link up.
Which small molecule is usually lost in condensation polymerisation?
- water (the answer)
- carbon dioxide
- hydrogen
- methane
One is lost each time two monomers join.
What type of polymer is nylon?
- a polyester
- a polyamide (the answer)
- an addition polymer
- a protein
It is made by condensation polymerisation.
Why do plastics cause pollution?
- They dissolve in water.
- They are not biodegradable. (the answer)
- They are magnetic.
- They react with air.
Microbes cannot break most of them down.
Proteins are polymers of what?
- sugars
- alkenes
- amino acids (the answer)
- fatty acids
Amino acids join by condensation to make proteins.

6 questions

Tap an answer and you’ll see straight away whether it’s right, and why.

Worksheet

4 questions, 8 marks. Write your answers on paper, then check them.

Polymers and plastics

Cambridge IGCSE Chemistry (9–1) 0971 · 8 marks · papermunch.org

Name ______________________________ Date ______________

State what is meant by a monomer and by a polymer.[2]
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A monomer is a small molecule that can join to many others. A polymer is a very long molecule made of many monomers joined together.
I got this one
Name the polymer made from chloroethene, and the type of polymerisation.[2]
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Poly(chloroethene) (PVC). Addition polymerisation.
I got this one
State one difference between addition polymerisation and condensation polymerisation.[2]
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In addition polymerisation the polymer is the only product; in condensation polymerisation a small molecule such as water is also formed. (Or: addition uses one kind of monomer with a C=C bond; condensation usually uses two kinds.)
I got this one
Give two environmental problems caused by plastics.[2]
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Any two: they are not biodegradable, so they fill landfill sites; they build up in the oceans and harm wildlife; burning them gives off toxic gases.
I got this one

Answers: Polymers and plastics

1. A monomer is a small molecule that can join to many others. A polymer is a very long molecule made of many monomers joined together.
2. Poly(chloroethene) (PVC). Addition polymerisation.
3. In addition polymerisation the polymer is the only product; in condensation polymerisation a small molecule such as water is also formed. (Or: addition uses one kind of monomer with a C=C bond; condensation usually uses two kinds.)
4. Any two: they are not biodegradable, so they fill landfill sites; they build up in the oceans and harm wildlife; burning them gives off toxic gases.