• Created by: Han.L
  • Created on: 15-04-15 12:59

Fossil Fuels and Crude Oil

Fossil Fuels

  • They are finite - They're either no longer being made or being made slowly
  • They're non-renewable - Being used up faster that they're being formed

Difficulties associated with the finite nature of crude oil:

  • All the readily extractable resources will be used up in the future
  • Finding replacements

How crude oil is made:

1. Dead plants and sea creatures sink to the bottom of the sea

2. Layers of sediment cover this and build up over time

3.Heat and pressure change it into crude coal, oil and natural gas over time

Hydrocarbon - Made up of molecules that contains hydrogen and carbon atoms ONLY

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Crude Oil in a Fractioning Column

Crude oil is a mixture of many different types of oil which are all hydrocarbons

Most hydrocarbons in crude oil are alkanes - They contain a single chain of carbon atoms with hydrogen atoms bonded along the side

Fractioning column:

Crude oil is heated at the bottom of a fractioning column

  • Oil that doesnt boil sinks and leaves as a thick liquid at the bottom
  • This is bitumen - its has a very high boiling point
  • Other fractions That contain mixtures of hydrocarbons with similar boiling points boil and their gases rise up the column
  • The column is cooler at the top
  • Fractions with lower boiling points exit at the top of the column

Crude oil can be seperated because the hydrocarbons in different fractions have differently sized molecules

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Fractional Distillation

1. The intermolecular forces are broken during boiling

2. The molecules of liquid seperate from eachother as molecules of gas

3. Large molecules such as Bitumen and Heavy Oil have strong forces of attraction

4. A lot of energy is needed to break the forces between the molecules

5. These fractions have higher boiling points

6. Smaller molecules such as petrol have weak attractive forces between them

7. They can be easily seperated

8. Less energy is needed to break the forces between these molecules

9. These fractions have low boiling points

The more carbon atoms a hydrocarbon atoms has, the higher its boiling point will be

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Problems in extracting Crude Oil

Transportation problems:

  • Oil sicks can damage bird's feathers and kill them
  • Clean-up operations use detergents that can damage wildlife

Political problems

  • UK's dependancy on oil and gas from politically unstable countries
  • Oil-producing nations can set high prices and cause problems for the future supply of non-oil producing nations

Demand Problems

  • There's high demand for Coal,Oil and Natural Gas
  • Conflict between the needs for making petrochemicals and for making fuels
  • A fraction called Naphtha is in high demand for use in medicine, plastics and dyes
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This is a process that turns large ALKANE molecules into smaller ALKENE molecules

And ALKENE molecule has a double bond,which makes it useful for making polymers

Cracking also helps oil manufactures match supply with demand for prodcuts like petrol

Catalytic Cracking

Catalyst - Something used to speed up areaction

When Large hydrocarbon molecules are broken down into smaller, more useful molecules using a catalyst its called catalytic cracking and it is an example of thermal decompisition

The amount of fossil fuels being burnt is increasing because populations are increasing

Governments are concerned because of the increasing carbon dioxide emissions that result when fossil fuels are burnt

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Burning hydrocarbon fuels in plenty of air produces carbon dioxide and water

Methane + Oxygen      Carbon Dioxide + Water

Complete combustion - Occurs when a fuel burns in plenty of oxygen

  • More energy is released in complete combustion than incomplete combustion
  • Toxic gas (carbon monoxide) and soot (carbon) is made during incomplete combustion

Incomplete combustion word equation:

Fuel + Oxygen    Carbon monoxide + Water


Fuel + Oxygen    Carbon + Water

Complete gives carbon DIOXIDE and water, incomplete gives carbon MONOXIDE/carbon and water

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Combustion and 'clean' air


Complete combustion symbol equation:

Incomplete combustion symbol equation:

'Clean' air

Nitrogen - 78%

Oxygen - 21%

Carbon Dioxide - 0.035%

These percentages don't change much because there is a balance between the processes that use up and make both carbon dioxide and oxygen

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The Carbon Cycle

The Carbon Cycle:

The arrows in the diagram show the direction of movement of carbon compounds

Over time the percentage of carbon dioxide in the air has increased due to:

  • Deforestation - As the number of rainforests are cut down, less photosynthesis takes place
  • Population increase - When the population increases so does the world's energy requirements
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The Atmosphere

The Atmosphere

Gases escaping from the centre of the earth formed the original atmosphere

Plants that could photosynthesis removed carbon dioxide from the air and added oxygen

Eventually the amount of oxygen reached its current level


Gases come from the centre of the earth through volcanoes in a process called degassing

Scientists analyse the composition of these gases to form theories about the original atmosphere


  • One theory is that the atmosphere was originally rich in water vapour and carbon dioxide
  • This vapour the condensed to form oceans ans the carbin dioxide dissolved in the water
  • The percentage of nitrogen slowly increased and,being unreactive, little nitrogen was removed
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The Atmosphere and Pollution Control

  • Over time organisms that could photosynthesise evolved and converted carbon dioxide and water into oxygen
  • As the percentage of oxygen in the atmosphere increased, the percentage of carbon dioxide decreased until today's levels were reached

Pollution control

It's important to control atmospheric pollution so the effects don't have an impact on:

  • People's health
  • The natural environment
  • The built up environment

Sulfur dioxide:

  • It's a pollutant that can cause difficulties to people with asthma
  • It dissolves in water to form acid rain that damages wildlife and limestone buildings

A car fitted with a catalytic converter changes carbon monoxide to carbon dioxide

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Hydrocarbon -  A compound that contains hydrogen and carbon atoms ONLY

Alkanes - Hydrocarbons that have single covalent bonds only

Alkenes - Hydrocarbons that have a double covalent bond between carbon atoms, double bonds involve 2 shared pairs of electrons

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Alkene test

Bromine is used to test for an alkene

  • When orange bromine water is added to an alkene it turns colurless (decolourises)
  • The bromine and alkene form a new compound by an addition reaction.
  • A dibromo compound forms which is colourless

Saturated and unsaturated hydrocarbons

Saturated compound - Has a single covalent bond between carbon atoms

  • Alkanes, like propane, are saturated (-) 

Unsaturated compound - Has at least 1 double covalent bond between carbon atoms

  • Alkenes, like propene, are unsaturated (=)
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Addition polymerisation - process in which many alkene monomers react to give a polymer
This reaction needs:

  • High pressure
  • Catalyst

How to recognise a polymer:
 You can recognise a polymer from its displayed formula by looking out for:

  • A long chain
  • The pattern repeating every 2 carbon atoms
  • 2 brackets on the end with an extended bond going through them
  • an 'n' after the brackets

Displayed formula of poly(ethene)

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Addition polymerisation

The displayed formula on an addition polymer:

  • Can be constructed when the displayed formula of its monomer is given

The displayed formula of a monomer:

  • Can be constructed when the displayed formula of an addition polymer is given

Displayed formula of an ethene monomer:

During addition polymeristion a long chain is made until it is stopped. The long molecule is Polyethene - the reaction causes the double bond in the monomer to break and each of the 2 carbon atoms forms a new bond

Addition polymerisation - involves the reaction of many unsaturated monomer molecules (alkenes) to form a saturated polymer

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Breathable polymers


  • Tough
  • Lightweight
  • Keeps water out
  • Keeps UV light out


  • does not let water through so sweat condenses and makes the wearer wet and cold inside their jacket


  • Has all properties of Nylon
  • But, is breathable
  • water vapour from sweat can pass through the membrane but rain water cannot
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GORE-TEX properties and polymers


  • Made from PTFE membrane
  • The holes in PTFE are too small for water to pass through but are big enough for water vapour to pass through
  • PTFE membrane is too fragile on its own and so it is laminated onto nylon to produce a stonger fabric

Disposing of polymers

Scientists are developing new types of polymers

  • Polymers that dissolve
  • Biodegradable polymers
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Issues with the use of exisiting polymers

Research into new polymers is important because there are environemntal and economic issues with the use of existing polymers

  • Disposal of non-biodegradable polymers means lanfill sites get filled quickly
  • Landfill means wasting land that could be used for valuable other purposes
  • Disposal by burning waster plastics makes toxic gasses
  • Disposal by burning or using landfill sites wastes crude oil used to make the polymers
  • It is difficult to sort out different polymers so recycling is difficult
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Stretchy and rigid polymers

Atoms in polymers are held together by strong covalent bonds

The properties fo plastics can be related to simple models of their structure

  • Plastics that have weak intermolecular forces between polymer molecules have low melting points and can be stretched easily as the polymer molecules can slide over eachother
  • Plastics that have strong forces between the polymer molecules (covalent bonds or cross linking bridges) have high melting points, they cannot be streched and are rigid

Intermolecular forces - weak forces of attraction between molecules and are not as strong as covalet bonds within molecules

If the intermolecular forces between 2 polymer molecules are weak, the plastic can be easily stretched

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Proteins and Carbohydrates

Protein molecules in eggs and meat permenantly change shape when eggs and meat are cooked

This is called denaturing

The texture of the egg or meat changes when it is cooked because the shapes of the protein molecules change permentantly

Potato is a carbohyrate which is easier to digest if it is cooked because:

  • The starch grains swell up and sread out
  • The cell alls rupture resulting in the loss of their rigid structure and a softer texture is prodcued

Baking powder (sodium hydrogencarbonate)

when it is heated it breaks down (decomposes) to give carbon dioxide

word equation:

symbol equation:

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Hydrophobic (oil or fat loving) - tail

Hydophilic (water loving) - head

Emulsifiers help to keep oil and water from seperating:

  • The hydrophilic end bonds to the water molecules
  • The hydrophobic end bons with the oil or fat molecules
  • The hydrophilic end is attracted to the water molecules which surround the oil, keeping them together

Image of an emulsiphier:

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Alcohols react with acids to make an 'ester' and water

alcohol + acid         ester + water

esters are used to maake perfumes

an ester can be made using this simple experiment:

  • The acid is addd to the alcohol and heated for some time
  • The condenser stops the gas from escaping and helps to cool it down again, so that it can react more
  • The condenser allows the reaction to go on for longer

(in the base: ethanioc acid, ethanol, concentrated sulphuric acid)

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Perfume properties


  • Must evaporate easily so that the perfume particles can reach the nose
  • be non-toxic so it isnt posionous
  • not react with water so the perfume does not react with perspiration
  • not irritate the skin so the perfume can be put directly on the skin
  • be insoluble in water so it canoot be washed off easily


A solution is a mixture of of a SOLVENT and a SOLUTE that does not seperate out

Esters can be used as SOLVENTS

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The volatility (ease of evaporation of perfumes) can be explained in terms of kinetic energy:

  • In order to evaporate, particles of a liquid need sufficient kinetic energy to overcome the forces of attraction to other molecules in the liquid
  • Only weak attractions exist between particles of the liquid perfume so it is easy to overcome these attractions as they have sufficient kinetic energy

water will not dissolve nail varnish colours:

  • The attraction between the water molecules is stonger than the attraction between the water molecules with the nail varnish molecules
  • The attraction between the nail varnish molecules is stronger than the attraction between water molecules with the nail varnish molecules

Intermolecular forces are weak forces of atraction between molecules and can easily be overcome with sufficient kinetic energy

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Colloids And Paints


PAINT is a colloid where the particles are mixed and dispersed with particles of a liquid (binding medium) but are not dissolved

The components of a colloid WILL NOT SEPERATE because the particles are scattered or dispersed throughout the mixture and are sufficiently small so as to not settle at the bottom

Paint Drying:

Most paints dry because:

  • Paints are applied as a thin layer
  • The SOLVENT evaporates

Emulsion paints are water based paints that dry when the solvent evaportaes

Oil paints dry because the solvent evaporates and the oil is oxidised by atmospheric oxygen

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Paint drying diagrams

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Thermochromic pigments

THERMOCHROMIC PGIGMENTS change colour at different temperatures

They are used:

  • As thermometers because they change colour when the temperature of a body or the temperature of a fridge rises
  • In the manufacture of some cups - the colour changes to show when they are hot
  • In electic kettles to keep users safe when boiling water
  • In babies spoons and bath toys, to warn if the spoon or toy is too hot to give to a baby

Thermochromic paints can be added to acrylic paints to make even more colour changes

If a blue thermochromic pigment which turns colourless when hot is added to yellow acrylic paint, the paint will appear green when cool and yellow when hot

Phosphorescent pigments:

They glow in the dark because they absorb and store energy and release the energy as light over a long period of time.  They are safer than the older, alternative radioactive paints.

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