Organic Chemistry

• Crude oil is a fossil fuel formed mostly from dead sea creatures, such as plankton
• Crude oil is a mixture of hydrocarbons, compounds made up of hydrogen & carbon atoms only
• Most hydrocarbons in crude oil are alkanes, which are chains of carbon atoms with as many hydrogen atoms bonded to them as possible
• General formula for alkanes: CnH₂n+2
• Properties of alkanes change with the number of carbons in the molecule:

  • Boiling point increases
  • Viscosity (thickness) increases
  • Flammability decreases
  • Amount of smoke/soot released when burned increases
• Fractional distillation is used to separate crude oil into different fractions of alkanes of different chain lengths
• Combustion of alkanes:

  • Complete combustion results in carbon dioxide and water
  • Incomplete combustion produces carbon monoxide or carbon/soot
• Air pollution from combustion:

  • Carbon dioxide
  • Water vapor
  • Carbon monoxide
  • Carbon/soot particulates
  • Sulfur dioxide
  • Nitrogen oxides
• Catalytic converters in cars convert harmful products into less harmful ones
• Cracking is a process to convert long alkanes into shorter hydrocarbons:

  • Catalytic cracking: high temperature & catalyst
  • Steam cracking: high temperature, pressure & steam
• Thermal decomposition of hexane can produce different products:

  • 19% C2H6
  • 6% C3H6
  • 11% C4H8
  • 64% other products, including alkenes
• Alkenes have less hydrogen than alkanes, making them unsaturated hydrocarbons
• Alkanes are saturated
• Smaller alkanes are used as fuels, while alkenes are used to make plastics/polymers
• Alkenes can undergo addition reactions where atoms are added to the two carbon atoms that were part of the double bond
• Alcohols have the functional group -O-H and their names end in -ol
• Alcohols are used as fuels, solvents, and disinfectants; ethanol is the alcohol in alcoholic drinks
• Alcohols dissolve well in water, giving a neutral pH
• Alcohols combust with oxygen to give CO₂ and water
• Alcohols can turn into carboxylic acids if exposed to oxygen or reacted with oxidising agents
• Carboxylic acids have the functional group -COOH
• Esters are formed by reacting an alcohol with a carboxylic acid in the presence of concentrated sulfuric acid as a catalyst
• Condensation polymers form when monomers react and join together, producing a small molecule like H₂O each time two monomers join
• Naturally occurring polymers include starch, cellulose, proteins, and DNA
• Hydrocarbons are compounds formed from carbon and hydrogen atoms only
• Alkanes are the simplest type of hydrocarbon with the formula CnH2n+2
• Alkanes are a homologous series, saturated compounds where each carbon atom forms four single covalent bonds
• The first 4 alkanes are methane (CH4), ethane (C2H6), propane (C3H8), and butane (C4H10)
• Hydrocarbon properties:

  Shorter chain hydrocarbons are less viscous, more volatile (lower boiling points), and more flammable
• Longer chains are the opposite in properties
• The properties of hydrocarbons affect how they are used
• Complete combustion:
• Occurs when there is plenty of oxygen
• Hydrocarbon + oxygen → Carbon dioxide & water (+ energy)
• During combustion, carbon and hydrogen from the hydrocarbon are oxidized
• Hydrocarbons are used as fuel due to the amount of energy they release during combustion
• Crude oil:
• A fossil fuel formed from the remains of plants & animals, mainly plankton, that died millions of years ago
• Fractional Distillation separates crude oil into different fractions, each containing hydrocarbons with a similar number of carbons and similar properties
• Uses + Cracking of Crude oil: