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C1b Oils, Earth and Atmosphere
Revision Notes




J. Wilkinson Jan 09 Page 1

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Reminder from C1a

Crude oil is a mixture of hydrocarbons
It can be split into fractions
Fractions with long hydrocarbon molecules aren't very useful.



Cracking Hydrocarbons
Cracking ­ Breaking large hydrocarbon molecules into smaller ones

- Thermal decomposition


smaller hydrocarbons

hot catalyst


vapour



hydrocarbon




Heat



Done in a catalytic cracker…

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Alkane Molecules Alkene Molecules
(reminder from first chemistry module) (Of interest in this module)
Saturated ­ Contain as many hydrogen atoms as Unsaturated ­ Contains fewer hydrogen atoms
possible
No double bonds Contains one carbon ­ carbon double bond
H H
H H
e.g. H C C H
C C…

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Making Polymers from Alkenes
Monomers - Small molecules (alkenes)



Polymers - Very long hydrocarbon molecules



Addition polymerisation - Adding lots of monomers together to make a polymer.



Plastic - Made of polymers


Addition
polymerisation




Monomer Polymer



Monomer Polymer Uses

Ethene Poly(ethene) Bags, bottles

Propene Poly(propene) Crates, ropes




J. Wilkinson Jan…

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Properties of Plastics
Long, tangled polymer molecules strong, flexible (bendy) plastics




H H H H H H H H

C C C C C C C C

H H H H H H H H




Strong bonds hold atoms together in a polymer
molecule



Thermosoftening Plastics Thermosetting Plastics
Weak intermolecular…

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Useful Polymers
Properties = how something behaves/what it is like.

Different polymers different properties different uses



e.g.
clear
poly(ethene) light weight Cola
strong
Transparent (clear) Drinks bottle




New Polymers

Scientists design new polymers for new jobs.

Smart polymer ­ Properties changed by light, temperature or other changes around them

e.g.…

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Problems with Polymers
Non ­ biodegradable ­ Don't rot, so fill up landfill sites (rubbish dumps)

Made from oil ­ oil is running out.




J. Wilkinson Jan 09 Page 7

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VEGETABLE OILS



Contain a lot of energy so .....




..... can be used ....... are
as fuels important foods



Extracted from seeds, nuts or
fruits by ...........



... pressing ......... distillation



Vegetable Oils




Contain molecules with
chains of carbon atoms, with
hydrogen atoms attached.




Unsaturated oils...

have carbon ­
carbon…

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Extracting Vegetable Oils

Extracting Vegetable Oils by Pressing Extracting Vegetable Oils by Distillation

Plant harvested Plant harvested



Crushed Crushed



Mixed with water Mixed with water



Pressed Mixture heated



Oil and water obtained Oil and some water evaporate (turn to gas)



Oil separates from water They condense (back to liquid)



Oil…

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Vegetable Oils as Food



Vegetable oils have higher boiling
Food absorbs oil when
points than water, so food cooked in
cooked in it
vegetable oil..........

Higher energy content in
food
... Cooks ..... has a
faster different flavour


......... has a ........ has a
different texture different colour




Vegetable Oils…

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