C.9 Crude Oil and Fuels
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Crude Oil: How
• ancient biomass (mostly plankton) • buried for millions of years • compressed at a high pressure and tempertaure • for millions of year
Crude oil: What
• A mixture of hydrocarbons
What is a hyrdocarbon
Compound that contains only carbon and hydrogen
Saturated Hydrocarbons
Hydrocarbons that contain only single bonds
Alkanes
General formula: - CnH2n+2 Name: - All end in -ane Formula: (n)carbons with (2n+2) hydrogens around it First 4: Methane Ethane Propane Butane
What is a homologous series
A family of hydrocarbons with similar chemical properties
Fractional Distilation Steps
• Crude oil is added to the furnace • Crude oil is heated and mist substances evaporate • The vapours pass into the fractionating column • Column is hotter at the bottom - when a gas reaches its boiling point it condense back to liquid • The smallest molecules stay as gases even at the top • The biggest molecules never boil and are collected at the bottom of the column
What is a fraction
A mixture of hydrocarbons with similar boiling points and properties
What fuels are produced from fractional distillation
petrol - cars keresene - air craft fuels desiel - diesel engine petroleum gas - fuel
Materials produced by the petrochemical industry
• Plastic • cosmetics • resins • fertilisers • detergents
Why are there so many different carbon compound
As carbon is able to bond in many different ways
How does hydrocarbon length effect its properties
• High boiling point = Longer chain • High viscosity = Longer chain • High Flammable = shorter chain • High Volatility = shorter chain The more flammable and volatile a fuel is the more useful it is (shorter chain = more useful)
Hydrocarbon Combustion
Complete - Only water and carbon dioxide released Incomplete (insufficient oxygen) - Water + carbon monoxide/soot
Cracking: Thermal Decomposition
• Uses heat to break down a molecule • From long chain alkane to short chain alkane and alkene
Catalytic cracking conditions
• Zeolite catalyst • High temp (lower than steam cracking)
Steam cracking conditions
• High temp (750C) • Steam (H2O gas)
How to test for an alkene
Bromine water - Alkane do not react with bromine - solution stays orange and clear • Alkene do react with water • Solution goes from orange and clear to clear and colourless
Why do we utalise cracking
• Create alkene • Used for plastics and polymers
Alkene
General formula: - CnH2n Name: - All end in -ene Formula: 2 carbons double bonded with hydrogens around it First 4: Ethene Propene Butene propene
What is an unsaturated hydrocarbon
• Have a double bond