Hydrocarbons and Polymers (2) Flashcards
What is the
general formula of alkanes?
CnH2n+2
(n is the number of carbon atoms)
What is the
functional group of alkenes?
C=C
(a double covalent bond between two different carbon atoms)
What is the
general formula of alkenes?
CnH2n
How can you
distinguish between alkanes and alkenes?
By adding bromine.
When bromine water is added to alkanes and they are shaken toether, no reaction will occur and it’ll stay bright orange. If it is added to alkene and shaken, an addition reaction occurs and the bromine water is decolourised.
Define
polymer.
a substance with a high relative molecular mass, made by joining up lots of small repeating units called monomers
What is
addition polymerisation?
when lots of small alkene molecules open up their double bonds and join together to form long-chain molecules
What are the properties of
poly(ethene)?
(3)
and what is it used for? (3)
- flexible
- electrical insulator
- cheap
it is used for:
- plastic bags
- bottles
- wire insulation
What are the properties of
poly(propene)?
(4)
and what is it used for? (3)
- flexible
- strong
- tough
- mouldable
it is used for:
- crates
- furniture
- ropes
What are the properties of
poly(chloroethene)?
(PVC) (2)
and what is it used for? (2)
- tough
- cheap
it is used for:
- window frames
- water pipes
What are the properties of
poly(tetrafluoroethene)?
(PTFE) (3)
and what is it used for? (2)
- unreactive
- tough
- non-stick
it is used for:
- non-stick pans
- waterproof clothing
Define
functional group.
a group of atoms that are responsible for the chemical properties of a compound
How is
polyester formed?
by the condensation polymerisation of dicarboxylic acid monomers and diol monomers
these form ester links
What is the
functional group of carboxylic acids?
-COOH
What is the
functional group of diols?
-OH
What are some examples of
naturally occurring polymers?
(3)
- DNA
- proteins
- starch
What is
DNA?
and what is it’s purpose?
a large molecule that takes a double helix structure
it is made of two polymer chains of four different types of monomers
What are the
two functional groups of amino acids?
-COOH and -NH2
How are
proteins formed?
by the condensation polymerisation of amino acids
What are
carbohydrates?
and what are they used for?
molecules containing carbon, oxygen and hydrogen
used by living things to produce energy
What is
starch?
a polymer made up of many smaller units of carbohydrates (nown as sugars) joined together in a long chain
What are the environmental and economic issues with the
raw materials of plastics?
Plastics are made from crude oil. This is a finite resource meaning that eventually it will all get used up and run out.
The more we use the crude oil products, the more expensive crude oil will become, so price of crude oil products will also increase.
Also, as resources dry up, we will have the issue of how to use the remaining oil.
What are the
two main disposal methods of plastics?
- landfill
- combustion
What are the key negatives of
landfill?
- lots of valuable land is quickly getting used up for use as landfill sites
- most polymers are non-biodegradable so will sit in landfill for many years
What are the positives and negatives of
disposal of polymers by combustion?
(1+, 1-)
+releases a lot of energy which can be used to generate electricity or heat homes
-toxic gases can be released from the combustion
What are the
positives of recycling polymers?
(5)
- reduces the amount of non-biodegradable waste filling up in landfill sites
- reduces emissions of greenhouse and toxic gases which can be released from burning polymers
- generally uses up less water and energy resources than making new plastic does
- reduces the amount of crude oil needed to produce more plastics
- recycling saves money and creates jobs
What are the
negatives of recycling polymers?
(5)
- polymers must be separated before they can be melted and reformed (which can be difficult expensive)
- it can be more expensive than producing new products from raw materials
- if polymers are mixed together, the quality of the final polymer product could be reduced
- polymers can only be recycled a finite amount of times
- melting down polymers can release dangerous gases into the atmosphere - these are harmful to plants and animals
