synthetic polymers

Question 1

polymers are

Answer 1

large molecules of high relative molecular mass and are made by linking together large numbers of smaller molecules called monomers

Question 2

polymerisation reactions usually require

Answer 2

high pressures and the use of a catalyst

Question 3

drawing polymers

Answer 3

Addition polymers are formed by the joining up of many monomers and only occurs in monomers that contain C=C bonds
One of the bonds in each C=C bond breaks and forms a bond with the adjacent monomer with the polymer being formed containing single bonds only
Many polymers can be made by the addition of alkene monomers
Others are made from alkene monomers with different atoms attached to the monomer such as chlorine or a hydroxyl group
The name of the polymer is deduced by putting the name of the monomer in brackets and adding poly- as the prefix
For example if propene is the alkene monomer used, then the name is polypropene
Polyethene is formed by the addition polymerisation of ethene monomers

Question 4

deducing the monomer from the polymer

Answer 4

Polymer molecules are very large compared with most other molecule
Repeat units are used when displaying the formula
To draw a repeat unit, change the double bond in the monomer to a single bond in the repeat unit
Add a bond to each end of the repeat unit
The bonds on either side of the polymer must extend outside the brackets (these are called extension or continuation bonds)
A small subscript n is written on the bottom right hand side to indicate a large number of repeat units
Add on the rest of the groups in the same order that they surrounded the double bond in the monomer

Question 5

deducing the polymer from the monomer

Answer 5

Identify the repeating unit in the polymer
Change the single bond in the repeat unit to a double bond in the monomer
Remove the bond from each end of the repeat unit and the subscript n (which can be placed in front of the monomer)

Question 6

additional polymers are formed by

Answer 6

the joining up of many small molecules to make strong C-C bonds; this makes additional polymers unreactive and chemically inert so don’t easily biodegrade

Question 7

land fills

Answer 7

Waste polymers are disposed off in landfill sites but this takes up valuable land, as addition polymers are non-biodegradable so micro-organisms such as decomposers cannot break them down
This causes sites to quickly fill up

Question 8

incineration

Answer 8

Polymers release a lot of heat energy when they burn and produces carbon dioxide which is a greenhouse gas that contributes to climate change
Polymers that contain chlorine such as PVC release toxic hydrogen chloride gas when burned
If incinerated by incomplete combustion, carbon monoxide will be produced which is a toxic gas that reduces the capacity of the blood to carry oxygen

Question 9

recycling

Answer 9

Polymers can be recycled but different polymers must be separated from each other
This process is difficult and expensive