Organic Chemistry

• A hydrocarbon is a molecule made only of carbon and hydrogen
• Crude oil is a mixture of substances, most of which are hydrocarbons
• Crude oil is a finite source - it will run out
• At the bottom of the fractionating column the boiling point and viscosity increases and the flammability and the volatility decreases
• Bitumen - used for roads and roofing
• fuel oil - fuel for ships, factories and central heating
• diesel oils - diesel fuels
• kerosine - jet fuel, paraffin for lighting and heating
• gasoline - petrol for vehicles
• refinery - liquid petroleum gas
• As the hydrocarbon chain length increases, the colour gets darker
• As the hydrocarbon chain length increases, the boiling point increases
• As the hydrocarbon chain length increases, the viscosity (thickness) increases
• As the hydrocarbon chain length increases, the flammability decreases
• As the hydrocarbon chain length increases, the volatility (how easily it changes from liquid to gas) decreases
• when the engine reaches a high temperature nitrogen and oxygen from the air react forming oxides of nitrogen

  These oxides of nitrogen mix with rain water to form nitric acid (acid rain)
• Sulphur from the fuel reacts with oxygen when burnt to form sulphur dioxide

  sulphur dioxide reacts with rain water to form sulfuric acid (acid rain)
• Cracking is a process to break large molecules into smaller ones which are more useful
• cracking is an example of thermal decomposition
• cracking produces alkenes and alkanes
• conditions needed for cracking: heat (600-700 degrees), catalyst is silica or alumina
• Fractional distillation:

  1. crude oil is a mixture so it has to be seperated into different fractions
  2. Crude oil is heated to make it vaporised
  3. Mixture of vapours go into the fractionating column at the bottom. The column is hot at the bottom and cooler at the top
  4. The vapours cool as they rise up the column
  5. Different fractions of the oil condense and are collected at different temperatures. Shorter lighter gases at the top
  6. At the bottom the length of the hydrocarbon chain increases. Fraction is darker
• Alkanes are saturated as they have singles bonds only
• Alkenes are unsaturated as they contain a c=c double bond
• Add Bromine water and if it turns colourless, the substance is unsaturated (an alkene)
• Add Bromine water and if it doesn't change colour then the substance is saturated (an alkane)
• Homologous series: can be represented by the same general formula, have the same functional group and have similar chemical properties
• When alkanes react with halogens it is a substitution reaction
• Polymerisation = joining of monomers to form polymers by addition reactions