Crude Oil & Fuels

Organic chemistry: Chemistry of carbon compounds, often obtained from living things

Element: 1 type of atom

Compound: 2 or more different elements chemically joined together

Mixture: 2 or more different elements which can be physically seperated

Oil: Made from bodies of sea creatures from millions of years ago

Crude Oil: Made of hydrocarbons ( These are made of ONLY hydrogen & carbon )

Crude oil is seperated by fractional distillation

Some substances in crude oil have different boiling points

Individual elements are not extracted, but groups with similar boiling points & properties, called fractions

Shorter molecules- ethane, propane etc. :

• Less viscous ( Less gloopy)
• More volatile ( Lower boiling point )
• More flammable

The opposite is true for longer molecules

Alkanes:

• These are saturated hydrocarbons
• The general formula for an alkane is: C  H
• Some examples:
  • Methane- 1 carbon
  • Ethane- 2 carbons
  • Propane- 3 carbons
  • Butane- 4 carbons etc.
• Contain single, covalent bonds

Alkenes:

• These are unsaturated hydrocarbons
• The general formula is: C  H
• Some examples: Ethene, Propene, Butene etc
• Contain one c=c double bond

Complete Combustion:

• Rapid reaction between a substance & oxygen that releases heat & light energy
• This occurs when there is plenty of oxygen- eg. bunsen burner
• Characteristics:Blue flame, Very hot, Not sooty

Hydrocarbon + Oxygen   Carbon dioxide + Water

Eg.  Propane + Oxygen   Carbon dioxide + Water

      C  H       + 5O           3CO                + 4H O

Incomplete Combustion:

• If there is a shortage of air, incomplete combustion takes place
• This produces carbon monoxide and/ or carbon instead of carbon dioxide & water
• It also releases less energy
• Carbon monoxide is poisonous gas which reduces the ability of blood to carry oxygen

When fossil fuels are burnt, sulphur impurities form sulphur dioxide, which causes acid rain

To prevent this, powdered calcium carbonate is mixed with water & reacted with sulphur dioxide

This makes neutral Calcium sulphate, which is used to make plaster

Calcium Sulphate + Sulphuric Acid    Calcium Sulphate + Carbon dioxide + Water

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Global Dimming: Reduction in the amount of sunlight reaching the Earth's surface

• Caused by particles from fossil fuels which collect water
• Water droplets act like mirrors & relfect sunlight
• Global dimming increases water droplets
• The more water droplets, the less sunlight reaches the Earth

Hydrogen:

• Clean
• Needs a different engine to use & energy from another source to create
• Isn't widely available & Hard to store

Biofuels: 

Biodiesel:

• Better for the environment & Cheaper
• Carbon neutral & Biodegradeable
• Requires large area to produce- destroys crop fields & habitats
• Freezes faster than diesel- can ruin engine

Ethanol:

• Carbon neutral
• Engines will nedd to be converted
• Isn't widely available & Can raise food prices