Synthetic polymers (Edexcel IGCSE Chemistry (Modular): Unit 2): Flashcards
Exam code: 4XCH1
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Define monomer.
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Define monomer.
A monomer is a small molecule that can join together with many other monomers to form a large polymer molecule.
What conditions are required for addition polymerisation?
Addition polymerisation requires:
High pressure
A catalyst
To draw the repeat unit of a polymer, change the .......... bond in the monomer to a single bond, then add a bond to .......... of the repeat unit.
To draw the repeat unit of a polymer, change the double bond in the monomer to a single bond, then add a bond to each end of the repeat unit.
True or False?
Addition polymerisation only occurs with monomers that contain C=C bonds.
True.
In addition polymerisation, one bond of the C=C double bond breaks in each monomer, allowing the monomers to join together in a long chain.
Define addition polymerisation.
Addition polymerisation is the process in which many small monomer molecules containing C=C double bonds join together to form a large polymer molecule, with no other products formed.
How do you deduce the monomer from the structure of an addition polymer?
To deduce the monomer, identify the repeat unit in the polymer, then change the single bond in the repeat unit back to a C=C double bond and remove the bonds at each end.
True or False?
The repeat unit of an addition polymer contains a C=C double bond.
False.
The repeat unit contains only single bonds. The C=C double bond is present in the monomer, and one bond breaks during polymerisation to form the chain.
How is the name of an addition polymer derived from its monomer?
The name of an addition polymer is formed by adding the prefix 'poly-' to the name of the monomer. For example, the monomer propene gives the polymer polypropene.
Complete the table showing addition polymers and their monomers.
Monomer
Polymer name
ethene
propene
chloroethene
Complete the table showing addition polymers and their monomers.
Monomer
Polymer name
ethene
poly(ethene)
propene
poly(propene)
chloroethene
poly(chloroethene)
Why are addition polymers non-biodegradable?
Addition polymers are non-biodegradable because they are held together by strong C-C bonds, making them chemically inert. Microorganisms such as decomposers cannot break them down.
True or False?
Addition polymers break down easily in landfill sites.
False.
Addition polymers are non-biodegradable, so microorganisms cannot break them down. This means they persist in landfill sites, quickly filling them up.
Define incineration.
Incineration is the burning of waste materials at high temperatures as a method of disposal.
When polymers are burned completely, they produce .......... and water. This gas contributes to .......... .
When polymers are burned completely, they produce carbon dioxide and water. This gas contributes to climate change.
What toxic gas is released when PVC is burned?
When PVC is burned, it releases toxic hydrogen chloride gas, because PVC contains chlorine in its structure.
True or False?
Burning polymers releases carbon dioxide, contributing to climate change.
True.
Carbon dioxide is a greenhouse gas produced when polymers burn. Increased levels in the atmosphere contribute to climate change.
What is the problem with disposing of addition polymers in landfill sites?
Addition polymers are non-biodegradable, so they do not break down in landfill. This takes up valuable land and causes landfill sites to fill up quickly.
If polymers undergo incomplete combustion, they produce .......... gas, which is toxic because it reduces the ability of the blood to carry .......... .
If polymers undergo incomplete combustion, they produce carbon monoxide gas, which is toxic because it reduces the ability of the blood to carry oxygen.
Define condensation polymerisation.
Condensation polymerisation is a process in which two different monomers join together in a long chain, with the removal of a small molecule (usually water) at each linkage.
What small molecule is released during condensation polymerisation?
The small molecule released during condensation polymerisation is water. One water molecule is produced per linkage formed.
True or False?
In condensation polymerisation, the polymer is the only product formed.
False.
Condensation polymerisation produces both the polymer and a small molecule, usually water, for every linkage formed. This is a key difference from addition polymerisation.
In a polyester, an ester linkage is formed when a -COOH group reacts with an .......... group, releasing one molecule of .......... .
In a polyester, an ester linkage is formed when a -COOH group reacts with an -OH group, releasing one molecule of water.
What two types of monomer react together to form a polyester?
A polyester is formed from:
A dicarboxylic acid (with a -COOH group at each end)
A diol (with an -OH group at each end)
Define biopolyester.
A biopolyester is a type of polymer synthesised from sugars and plant oils using microorganisms. Biopolyesters are biodegradable, breaking down naturally in the environment.
How can you deduce the monomers from the structure of a polyester?
Identify the ester linkages (-COO-) in the polymer, then break the C-O single bond at each linkage and add water to complete the molecules. This gives the dicarboxylic acid and diol monomers.
True or False?
Biopolyesters are biodegradable.
True.
Biopolyesters can be broken down naturally in the environment after their intended use, making them a more sustainable alternative to non-biodegradable plastics.
Complete the table comparing addition and condensation polymerisation.
Feature
Addition polymerisation
Condensation polymerisation
Number of monomer types
Small molecule released?
Bond broken in monomer
Complete the table comparing addition and condensation polymerisation.
Feature
Addition polymerisation
Condensation polymerisation
Number of monomer types
one
two
Small molecule released?
no
yes (water)
Bond broken in monomer
C=C double bond
functional groups react
What is terylene and how is it formed?
Terylene is a polyester formed by condensation polymerisation between a dicarboxylic acid and a diol. An ester linkage forms at each join, with a water molecule released per linkage.
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