Hydrocarbons and Polymers (2)
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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 (known 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? (2)
• 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