Topic 11 Flashcards
What are addition polymers
Relatively large molecules made by combing smaller molecules contains c- c bonds
-
A polymer is a substance :
Of high average relative molecular mass, Mr
Made up of small repeating units
Poly(ethene) is a polymers made by combining many
ethene molecules (monomers)
Properties of poly(ethene)
Flexible cheap good electrical insulator
Use - plastic bags plastic bottles and cling film
Properties of poly(propane)
Flexible shatterproof has a high softening point
Uses- buckets and bowls
Properties of poly(chloroethene)
PVC
Tough cheap long lasting good electrical insulator
Use - window frames gutters and pipes insulation for electrical wires
Properties of PTFE
poly(tetrafluoroethene)
Tough slippery resistant to corrosion good electrical insulator
Uses - non stick coatings for frying panda containers for corrosive substances and insulation for electric wires
What are polyesters
Condensation polymers rather than addition polymers
Two monomers
Polyesters need two different monomers
1- a molecule containing two carboxylic acid croutons
1- a molecule contains two alcohol groups
When does an Ester link form?
Each time two different monomers react together
One molecule of water forms each time an water link forms
Condensation polymerisation
When the two different monomers react together, producing a water molecule
The other molecule has a carboxylic acid group and an alcohol group
These groups can react with more monomers
This process continues producing a very long polyester molecule
What’s DNA
Deoxyribonucleic Acid
Found in nucleus of cells “double helix” structure
DNA is a polymer made from monomers called
Nucleotides
What are proteins
Polymers made from monomers called amino acids
Manufacture of polymers
Crude oil is the main raw material needed to make addition polymers and most condesnsatuon polymers. Crude oil is:
- a finite resource
- a non-renewable resource
- often imported by users - it’s supply and cost vary over time
Polymer problems
Non-biodegradability
Most artificial polymers are not biodegradable :
This is useful because objects made from polymers last a long time
This is a problem because objects made from polymers do not break down easily when they are disposed of:(
What does biodegradable mean
Materials eventually rot away:
Microbes feed on them
This breaks them down
Four ways to dispose of polymers
Landfill sites
Burning
Biodegradable polymers
Recycling
Landfill sites
:(
Polymers are not biodegradable
They last for many years
We are running out of landfill sites
Burning polymers
:(
Many polymers release toxic gases when they Burn
Biodegradable polymers
:)
These are being developed
They will not rot away in landfill sites
Recycling of polymers
:)
Melting and reforming into new objects
Breaking down into new raw materials
Advantages and disadvantages of landfill sites
Most waste goes into landfill
Waste is disposed of quickly
Waste is out of sight once it is covered over
:( space for landfill sites is running out
Most polymers are not biodegradable and will last for many years
Landfill sites are unsightly and attravtcpeats
The alcohols form a
Homologous series of compounds
The alcohols:
- have the same functional group, -OH
- have similar chemical properties
- differ in the molecular formulae of neighbouring members by CH2
- show a gradual variation in physical properties, such as boiling points
Alcohol names
End in ol
Methanol
Ethanol
Structure of alcohols
Has a hydroxyl group
Methanol, ethanol and propanol all:
Dissolve in water to form a neutral solution
React with sodium to produce hydrogen
Burn in air :
For example-
Methanol + oxygen -> CO2!+ water
Burning or combustion is an example of
An oxidation reaction
Ethanol burns in air
Ethanol + oxygen -> CO2 + water
Ethanol can also be oxidised to ethanoic acid by :
Chemicals called oxidising agents or
The action of microbes
Ethanoic acid is the main acid in vinegar
Formula for ethanol
C2H5OH
Ethanol is produced from
Carbohydrates in aqueous solution by a process called fermentation
Carbon dioxide is also produced in this reaction
The carbohydrates can be sugars from fruit such as grapes or from the breakdown of starch from wheat or barley
Yeast is a
Single-felled fungus
It provides enzymes for fermentation to happen
Glucose -> ethanol + CO2
Explain why the fermentation mixture must be kept warm and under anaerobic conditions
The reaction is too slow at low temperatures and the yeast enzymes do not work at Hugh temperature
Fermentation is a type of anaerobic respiration if oxygen is present aerobic respiration happens instead producing only a carbon dioxide and water
Fractional distillation is used to obtain a concentration solution of ethanoic
This works because :
Ethanol has a lower boiling point than water
It is not possible to obtain pure ethanol by this method alone the small amounts of water that remains must be absorbed chemically
Carboxylic acids form a
Homologous series of compounds
The carboxylic acids :
Have the same functional group, -COOH
Have similar chemical properties
Differ in the molecular formulae of neighbouring members by CH2
Show a gradual variation in physical properties such a sbioiling points
Names of carboxylic acids
End in anoic acid
Methanoic acid
Ethanoic acid
Structure of carboxylic acid
Has a carboxylic group
Reactions of carboxylic acids
Have the typical properties of acids they can:
• reactxwith carbonated to produce a salt water and carbon dioxide
•react with magnesium and other reactive metals to produce a salt and hydrogen
•dissolve in water to produce acidic solutions
Carboxylic acids are
Weak acids
Weak acids
Only partially dissociate into ions when they dissolve in water eg
Ethanoic acid reversible Ethanoate ion + hydrogen ion
At the same concentration weak acids have a higher pH than strong acids such as hydrochloride acid
What are nanoparticles
Structure consisting of only a few hundred atoms
Nanoparticles have a very small size so
Nanoparticulate materials have different properties from the same substance in larger pieces as a bulk material
Nanoparticles are useful for
Sunscreens - they still absorb harmful ultraviolet light from the sun but cannot be seen on the skin
Lightweight strong materials - such as carbon nanotube in tennis rackets
Future drug delivery systems - buckyballs consist of hollow balls of carbon atoms
Surface area to volum for nanoparticles
Very large
Therefor useful for catalysts eg as coatings for self-cleaning surfaces and clothes
There are possible hazards associated with the use of nanoparticles they mayb :
Be breathed in, absorbed through the skin or transported into cells
Take a long time to break down
Attract toxic substances to their surfaces
The risks to health and the environment may be difficult to predict and to measure
General properties o glass ceramics
Transparent Hard but brittle Poor conductors of heat and electricty Window glass Bottles
General properties of clay ceramics
Opaque Hard but brittle Poor conductors of heat and electricity Bricks China Porcelain
General properties of polymers
Transparent -> translucent -> opaque
Poor conductors of heat and electricty m
Often tough and ductile
Bottles crates carrier bags
General Properties of metals
Can be polished to a shine
Good conductors of heat and electricity
Hard tough and ductile
Cars bridges
Define brittle
Will crack or break when hit
Define brittle
Will crack or break when hit
Define tough
Resists cracking and breaking
Define ductile
Can be bent, twisted or stretched without cracking or breaking
