Chemistry - Other products from crude oil

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  • Created by: becky.65
  • Created on: 14-05-15 17:19
What fractions are usually cracked?
Long chain fractions
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Why are long chain fractions cracked?
It produces saturated hydrocarbons which are used as fuels and unsaturated hydrocarbons
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How do we crack hydrocarbons?
By passing the vapours over a hot catalyst or by mixing them with steam and heating them to a very high temperature
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What is the word equation for cracking decane?
decane -----------------------------> pentane + propene + ethene
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What are alkenes?
Unsaturated hydrocarbons
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What do unsaturated compounds contain?
At least one double bond between their carbon atoms
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In a positive text for an unsaturated hydrocarbon, what colour does bromine water turn?
From orange to colourless
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What is the general formula for alkenes?
CnH2n
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How can Ethanol for industrial use as a fuel or solvent be made?
By cracking ethene with steam
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What is the word equation for cracking ethene?
ethene + steam ethanol
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What is the symbol equation for cracking ethene?
C2H4 + H2O C2H5OH
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What is this reaction called?
Hydration
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How can we make plastics?
Using the chemicals from crude oil
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How can we make different types of plastics?
By using different monomers
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What is the polymer made from ethene called?
Poly(ethene) or polythene
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What are the properties of poly(ethene)?
Easy to shape, strong and transparent
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What are some uses of poly(ethene)?
Plastic carrier bags, some drink bottles, dustbins, washing-up bowls and clingfilm
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What is the polymer made from propane called?
Poly(propane)
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What are the properties of poly(propane)?
Strong and tough
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What are some of the uses of poly(propane)?
Carpets, milk crates and ropes
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What happens when alkene molecules join together?
The double bond between the carbon atoms in each molecule 'opens up'. It is replaced by single bonds as thousands of molecules join together?
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What is the reaction called when these molecules join together?
Polymerisation
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What are the two types of poly(ethene)?
High density (HD) and low density (LD)
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How is low density poly(ethene) made?
Using very high pressures and a trace of oxygen
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How is high density poly(ethene) made?
Using a catalyst at 50 degrees and a slightly raised pressure
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Why does low density poly(ethene) have a low density?
The polymer chains are randomly branched and they can't pack closely together
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Why does high density poly(ethene) have a high density?
It is made up of straighter poly(ethene) chains and they can pack more closely together than branched chains
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Why do thermosoftening polymer soften?
The forces between the polymer chains are weak. When we heat the polymer, the weak intermolecular forces are broken. The polymer becomes soft. When the polymer cools down, the intermolecular forces bring the polymer back together
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Why don't thermosetting polymers soften?
The monomers make covalent bonds between the polymer chains when they are first heated in order to shape them. The covalent bonds stop the polymer from softening. The covalent 'cross links' between chains do not allow them to separate
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What some new and useful polymer developments?
Fillings for teeth, softer lining for dentures, packaging materials, implants that can slowly release drugs into a patient
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How do light-sensitive plasters work?
By using a light-sensitive polymer when the lower layer of the plaster is exposed to the light, the adhesive becomes less sticky
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What are hydrogels?
Polymer chains with a few cross-linking units between chains
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What are hydrogels used for?
Wound dressings and contact lenses
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Why do shape memory polymers make stitching in awkward place easier
When it is used to stich a wound loosely, the temperature of the body makes the thread tighten and close the wound, applying just the right amount of force
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What is a smart polymer?
One that changes in response to changes in its surroundings
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Other cards in this set

Card 2

Front

Why are long chain fractions cracked?

Back

It produces saturated hydrocarbons which are used as fuels and unsaturated hydrocarbons

Card 3

Front

How do we crack hydrocarbons?

Back

Preview of the front of card 3

Card 4

Front

What is the word equation for cracking decane?

Back

Preview of the front of card 4

Card 5

Front

What are alkenes?

Back

Preview of the front of card 5
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