Synthetic polymers (Edexcel IGCSE Science (Double Award): Chemistry): Flashcards
Exam code: 4SD0
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- FrontAddition Polymers
Define addition polymerisation.
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Define addition polymerisation.
Addition polymerisation is a reaction in which many small monomer molecules containing a C=C double bond join together to form a large polymer molecule, with no by-products.
True or False?
Addition polymerisation produces by-products alongside the polymer.
False.
In addition polymerisation, only one product is formed. All the atoms in the monomers are incorporated into the polymer chain, with no by-products.
In addition polymerisation, the C=C double bond in each monomer .......... to form a .......... bond, linking the monomers into a polymer chain.
In addition polymerisation, the C=C double bond in each monomer opens to form a single bond, linking the monomers into a polymer chain.
What monomer is used to make poly(ethene), and what type of bond does it contain?
Poly(ethene) is made from ethene monomers. Each ethene molecule contains a C=C double bond, which opens during addition polymerisation to link the monomers into a chain.
Define repeat unit (in polymer chemistry).
A repeat unit is the smallest group of atoms that is repeated throughout a polymer chain. It is drawn inside brackets with a subscript n and bonds extending outside the brackets.
True or False?
To draw a repeat unit from a monomer, replace the C=C double bond with a single bond and add extension bonds at each end.
True.
The double bond in the monomer becomes a single bond in the repeat unit. Bonds are added to each end of the unit, extending outside the brackets, with a subscript n to indicate the large number of repeating units.
How do you deduce the monomer from a polymer repeat unit?
To deduce the monomer from a polymer repeat unit, change the single bond in the repeat unit back to a C=C double bond, then remove the extension bonds at each end and the subscript n.
The name of an addition polymer is formed by putting the name of the .......... in brackets and adding the prefix .......... .
The name of an addition polymer is formed by putting the name of the monomer in brackets and adding the prefix poly-.
Define non-biodegradable.
A non-biodegradable material is one that cannot be broken down by microorganisms such as decomposers. Addition polymers are non-biodegradable due to their strong C-C bonds.
True or False?
Burning addition polymers damages the ozone layer.
False.
Burning addition polymers releases toxic gases into the atmosphere, but it does not damage the ozone layer. Ozone depletion is caused by entirely different chemicals.
Why are addition polymers difficult to dispose of in landfill sites?
Addition polymers are difficult to dispose of in landfill because they are non-biodegradable. Microorganisms cannot break down their strong C-C bonds, so they persist in the ground and cause landfill sites to fill up quickly.
Incomplete combustion of addition polymers produces toxic .......... gas, which reduces the ability of the blood to carry ...........
Incomplete combustion of addition polymers produces toxic carbon monoxide gas, which reduces the ability of the blood to carry oxygen.
True or False?
Burning PVC produces toxic hydrogen chloride gas.
True.
PVC contains chlorine, which is released as hydrogen chloride gas when the polymer is incinerated. This is a significant environmental and health concern.
Why does burning waste polymers contribute to climate change?
Burning waste polymers contributes to climate change because combustion releases carbon dioxide, which is a greenhouse gas. Rising carbon dioxide levels in the atmosphere cause global warming.
Define inert (in the context of addition polymers).
An inert substance does not readily react with other chemicals. Addition polymers are inert, so they are not attacked by the water, acids or alkalis present in soil and landfill.
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