SC22-24 Flashcards
What are alkanes?
Saturated hydrocarbons
What is a homologous series?
A group of chemicals that have similar chemical structures.
What is the general formula for alkanes?
CnH2n+2
What are the first four alkanes?
Methane - CH4
Ethane - C2H6
Propane - C3H8
Butane - C4H10
Why are alkanes saturated?
All of the atoms have formed bonds with as many other atoms as they can.
What are alkenes?
They’re a homologous series of hydrocarbons with 1 C=C functional group.
What is a functional group?
It’s a group of atoms that determine how a molecule reacts.
What is the general formula for alkenes?
CnH2n
Why are alkenes unsaturated?
Because they can make more bond.
The double bond can open up, allowing the two carbon atoms to bond with other atoms.
What’s the test for alkenes?
Use bromine water.
When shaken together, an alkene will decolourise bromine water, turning it from orange to colourless.
This is because an addiction reaction takes place.
What are polymers?
Its a large molecule made from lots of small molecules (monomers) joined together.
What is polymerisation?
The process in which monomers join together.
What is addition polymerisation?
Lots of unsaturated monomer molecules (alkenes) can open up their double bonds and join together to form polymer chains.
What are the properties and uses of poly(ethene)?
Flexible, electrical insulator and cheap
Plastic bags, bottles and wire insulation
What are the properties and uses of poly(chloroethene)?
Tough and cheap
Window frames, water pipes and soft toys.
What are the properties and uses of poly(propene)?
Flexible, strong and mouldable
Crates, furniture and ropes
What are the and uses of poly(styrene)?
Egg boxes and foam packaging
What are some of the naturally occurring polymers?
DNA
Amino acids
Carbohydrates
What are polymers made from?
Crude oil
What does biodegradable mean?
Naturally broken down in the environment by microbes.
What is an advantage and disadvantage of synthetic polymers being non-biodegradable?
Advantage - durable
Disadvantage - can’t be disposed of easily
What are the problems when polymers are disposed of at landfill?
- A lot of plastics get dumped in landfill. This is usually when different polymers are too difficult or expensive to separate and recycle.
- Lots of valuable land is quickly getting used up for use as landfill site.
- Most polymers are non-biodegradable. This means they will sit in landfill for years and years.
What are the problems when polymers are disposed of by combustion?
- Burning plastics produces a lot of energy and this can be used to generate electricity. However…
- If not controlled, toxic gases can be released fro the combustion of plastics. For example all plastics produce CO^2.
- Carbon dioxide contributes to global warming.
What are the advantages of recycling polymers?
- Reduces the amount of non-biodegradable waste filling up landfill sites.
- Reduces emissions of greenhouse and toxic gases which can be released form burning them.
- Recycling generally uses up less water and energy resources than when making new plastics.
- Rescues the amount of crude oil needed to produce more plastics.
- Recycling generally saves money and creates jobs.
