GCSE Chemistry B - OCR - C1

Fossil Fuels
1. Examples of fossil fuels: crude oil, coal and natural gas.
2. Formed over millions of years.
3. Finite and non-renewable because they are used up much faster than new supplies can be formed.
4. Can be used as a source of fuel or chemicals.
5. Scientists are now looking for alternatives for crude oil due to it running out quickly.
  1. Crude OIl
    1. Transported to refineries through pipelines and oil tankers.
      1. Oil often spills from the tanker and floats on the sea's surface - this is known as slick and it can harm wildlife and damage beaches.
        Detergents are used in order to break up oil slicks.
    2. The oil affects alot of wildlife. The chemicals are toxic and can harm and kill wildlife.
    3. Found in the Earth's crust - pumped to the surface.
    4. Is a mixture of hydrocarbons and is formed from dead marine organisms
Fractional distillation
1. The process of separating crude oil into useful fractions (parts) that contain mixtures of hydrocarbons with similar boiling points, is called fractional distillation.
  1. Crude oil is a mixture of hydrocarbons - a molecule that contains only hydrogen and carbon atoms.
2. Crude oil is heated in a fractionating column.
  1. This column has a temperature gradient.
    1. This means that, fractions with low boiling points leave at the top of the fractionating column and fractions with high boiling points leave at the bottom of the fractionating column.
3. The order of the fractions (from the fractionating column) from the top to bottom are: liquefied petroleum gas (LPG), petrol (gasoline), paraffin (aircraft fuel), diesel, lubricating oil, fuel oil, bitumen (tar)
Cracking
1. Hydrogen molecules can be described as alkanes and alkenes. Large alkane molecules can be broken down into smaller, more useful, alkane and alkene molecules - this is the industrial process called cracking.
2. Needs ta catalyst, a high temperature and high pressure.
3. Used to make more petrol from naptha. It can also be used to make alkene molecules that may be used to make polymers.
Forces between molecules
1. A hydrocarbon molecule has: strong covalent bonds between the atoms in the molecue and weak intermolecular forces (this is forces of attraction between molecules).
  1. Longer hydrocarbons have stronger intermolecular forces than the forces between shorter hydrocarbons.
3. When a liquid hydrocarbon is boiled, its molecules move faster and faster until all the intermolecular forces are broken and it becomes a gas.
4. Small molecules have very weak forces of attraction between them and are easily overcome by heating.
  1. It is their boiling points which allow us to seperate a mixture of hydrocarbons (eg. crude oil) by the process of distillation.
Combustion
1. Incomplete combustion
2. Complete Combustion
  1. Of a hydrocarbon (fuel)
3. When fuels react with oxygen (in air), they burn snd release useful heat energy.
Clean Air
Making polymers
1. Designer Polymers
Cooking and Food Additives

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GCSE Chemistry B - OCR - C1

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