OIL and HYDROCARBONS

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OIL and HYDROCARBONS

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The origins of oil

• Crude oil is formed from organic material of the
  remains of plant and animal organisms that lived
  millions of years ago.  These remains form
  sediments e.g. at the bottom of seas, and become
  buried under layers of sedimentary rock.
  They decay, without air (oxygen), under the
  action of heat and pressure to form crude oil
  over millions of years.
• It is a fossil fuel because it is formed from
  once living organisms and the Sun is the original
  source of energy. It is a non-renewable and
  finite (limited reserves) energy resource because
  it takes millions of years to form and we burn it
  faster than it is formed! It is also known as a
  finite energy resource because it will eventually
  run out! We do not have unlimited oil reserves!
• When the fossil fuels are burned the 'carbon', as
  carbon dioxide, is returned to the living
  environment, gets used up in photosynthesis, the
  plant material decays or is eaten by animals, so
  completing the carbon cycle.

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Alkenes

• Alkenes are hydrocarbons containing a double bond
  as well as single bonds. These are called
  unsaturated molecules because two atoms can join
  onto the bond when it opens up. The first two in
  the series are shown below. They are extremely
  reactive and important compounds in the chemical
  industry and are converted into very useful
  compounds e.g. plastics. They are made from
  cracking processes.

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Hydrocarbons

• Hydrocarbons are colourless. Bromine dissolved in
  water or trichloroethane solvent forms an orange
  (yellow/brown) solution. When bromine solution is
  added to both an alkane and an alkene the result
  is quite different. The alkane solution remains
  orange - no reaction. However, the alkene
  decolourises the bromine as it forms a colourless
  dibromo-alkane compound - see equations.

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Diagram
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Crude Oil

• Crude oil is the term for "unprocessed" oil, the
  stuff that comes out of the ground. It is also
  known as petroleum. Crude oil is a fossil fuel,
  meaning that it was made naturally from decaying
  plants and animals living in ancient seas
  millions of years ago -- anywhere you find crude
  oil was once a sea bed. Crude oils vary in
  colour, from clear to tar-black, and in
  viscosity, from water to almost solid.

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• Crude oils are such a useful starting point for
  so many different substances because they contain
  hydrocarbons. Hydrocarbons are molecules that
  contain hydrogen and carbon and come in various
  lengths and structures, from straight chains to
  branching chains to rings.

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what makes them exiting

• There are two things that make hydrocarbons
  exciting to chemists
• Hydrocarbons contain a lot of energy. Many of the
  things derived from crude oil like gasoline,
  diesel fuel, paraffin wax and so on take
  advantage of this energy.
• Hydrocarbons can take on many different forms.
  The smallest hydrocarbon is methane (CH4), which
  is a gas that is a lighter than air. Longer
  chains with 5 or more carbons are liquids. Very
  long chains are solids like wax or tar. By
  chemically cross-linking hydrocarbon chains you
  can get everything from synthetic rubber to nylon
  to the plastic in tupperware. Hydrocarbon chains
  are very versatile!

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What is it made of

• On average, crude oils are made of the following
  elements or compounds
• Carbon - 84
• Hydrogen - 14
• Sulfur - 1 to 3 (hydrogen sulfide, sulfides,
  disulfides, elemental sulfur)
• Nitrogen - less than 1 (basic compounds with
  amine groups)
• Oxygen - less than 1 (found in organic compounds
  such as carbon dioxide, phenols, ketones,
  carboxylic acids)
• Metals - less than 1 (nickel, iron, vanadium,
  copper, arsenic)
• Salts - less than 1 (sodium chloride, magnesium
  chloride, calcium chloride)

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Hydrocarbons

• Crude oil is a mixture of many compounds, most of
  them hydrocarbons.
• Hydrocarbon molecules vary a great deal as to how
  many atoms they contain. A molecule of methane -
  the main component of natural gas - consists of
  just one carbon atom and four hydrogen atoms
  while a molecule of polyethelene is a long chain
  of thousands of carbon and hydrogen atoms.

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Hydrocarbons
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The end