New Chemistry For You

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Summary Crude oil and polymers

• Crude oil contains a mixture of hydrocarbons.
• Mixtures consist of two or more elements or
  compounds which are not chemically bonded
  together. A mixture is easily separated
• The hydrocarbons present in crude oil are
  compounds made of hydrogen and carbon atoms only.
• The hydrocarbon mixture in crude oil can be
  separated using fractional distillation.

OCR C1 part 2 Chapter 11 and 12
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Summary Crude oil and polymers

• Alkane molecules are hydrocarbons which are said
  to be saturated.
• These saturated molecules contain carbon carbon
  single covalent bonds. (C-C)
• Each alkane has the same general formula CnH2n2
• An example of an alkane is ethane C2H6

OCR C1 part 2 Chapter 11 and 12
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Summary Crude oil and polymers

• Crude oil is separated into groups of useful
  substances (fractions) by a process called
  fractional distillation.
• This process works because different hydrocarbons
  have different size molecules and different
  boiling points.
• The smaller hydrocarbon molecules
• have lower boiling points,
• are lighter in colour,
• are easier to light, burning with a cleaner
  flame,
• are thinner and more runny.

OCR C1 part 2 Chapter 11 and 12
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Summary Crude oil and polymers

• The hydrocarbon fractions in crude oil are
  separated by using a two stage process, firstly
• the oil is evaporated by heating and then
• the oil vapours are cooled and condensed at
  different temperatures.

OCR C1 part 2 Chapter 11 and 12
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Summary Crude oil and polymers

• The larger molecules obtained from crude oil can
  be broken down or thermally cracked into smaller,
  more useful molecules.
• This is done at a high temperature, using a
  catalyst.
• During cracking, smaller alkanes and unsaturated
  hydrocarbon molecules called alkenes are formed.
• Alkenes have the same general formula CnH2n

OCR C1 part 2 Chapter 11 and 12
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Summary Crude oil and polymers

• An example of an unsaturated hydrocarbon (an
  alkene) is ethene.
• This alkene molecule contains a carbon carbon
  double covalent bond. (CC)
• Ethene can be reacted with steam in the presence
  of a catalyst (phosphoric acid) to produce
  ethanol. This process is called hydration.
• An equation for the hydration of ethene is
• C2H4 H20 C2H5OH H

OCR C1 part 2 Chapter 11 and 12
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Summary Crude oil and polymers

• Unsaturated organic compounds (the alkenes) which
  contain carbon carbon double bonds, are said to
  be unsaturated.
• These unsaturated compounds may be tested for by
  using bromine water.
• The bromine water turns from yellow/orange to
  colourless when reacted with an alkene.

OCR C1 part 2 Chapter 11 and 12
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Summary Crude oil and polymers

• Ethene can be polymerised to produce a long chain
  polymer. This process is called polymerisation.
• The properties of a polymer depend upon what they
  are made from and the conditions under which they
  are made. Examples of two common polymers include
  poly(ethene) and poly(propene)
• Poly(ethene) may be used for buckets and carrier
  bags.
• Poly(propene) may be used for crates and fishing
  nets.

OCR C1 part 2 Chapter 11 and 12
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Summary Crude oil and polymers

• Polymers may also be used for
• Packaging and Waterproofing fabrics
• Dental polymers and Wound dressings
• Hydro-gels and Smart materials
• Shape memory plastics.
• The non biodegradable nature of many plastics
  leads to problems in waste management.

OCR C1 part 2 Chapter 11 and 12
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