Other useful substances from crude oil
- Created by: Freya Woolley
- Created on: 06-05-15 20:32
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- Other useful substances from crude oil
- Cracking
- Thermal de-composition
- Breaking long hydrocarbon chains into shorter ones
- Shorter chains are more useful, more flammable
- Thermal de-composition
- Alkenes
- Cracking produces shorter chains a mixture of alkenes and alkanes
- Unsaturated- at least one C-C double bond
- CnH2n
- Ethene, propene, butene
- Used to make plastics
- More reactive
- Test- add bromine water and shake gently
- Alkane- no change, orange --> orange
- Alkene- orange --> colourless
- Polymers
- Large molecule made of hundreds of small molecules (monomers)
- Addition poly-merisation, monomers added together to form a long chain
- Often alkenes
- Low- density polythene- plastic bags
- Branched polymer chain- cannot pack closely together
- Soft, easy to melt
- Branched polymer chain- cannot pack closely together
- High density polyethene- plastic containers, pipes
- Straight polymer chains- can pack closely together
- Rigid, harder to melt
- Straight polymer chains- can pack closely together
- Thermo-softening polymers
- Consist of individual, tangled polymer chains
- Weak inter-molecular forces between chains
- Slide past each other, low mp, flexible & stretchy
- Consist of individual, tangled polymer chains
- Thermo-setting polymers
- Form cross links when melted so set permanently
- Rigid, can't be stretched, high mp
- Cross links are very strong
- Form cross links when melted so set permanently
- Problems with plastic
- Recycle, burry it (land fill), burn it
- Polymers are non-biodegradble
- Can't be broken down by micro-organisms
- Take hundreds of years to decompose
- Take up a lot of space
- Wildlife can get trapped in waste
- Solution:
- Use cornstarch to build up the plastic
- The micro-organisms in the soil feed on the cornstarch, helping break it down
- Needs a lot of space to grow
- Cracking
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