Hydrocarbons

• Organic chemistry is about compounds that contain carbon
• Hydrocarbons are the simplest organic compounds
• Hydrocarbons only contain hydrogen and carbon atoms
• C10H22 (decane, an alkane) is a hydrocarbon, but HC3COOC3H7 (an ester) is not - it contains oxygen
• Alkanes have all C-C single bonds
• Alkanes are the simplest type of hydrocarbon there is. They have the general formula: CnH2n+2
• The alkanes are a homologous series - a group of organic compounds that react in a similar way
• Alkanes are saturated compounds - each carbon atom forms 4 single covalent bonds
• The first 4 alkanes are methane, ethane, propane and butane
• A drawing showing all the atoms and bonds in a molecule is called a displayed formula
• Methane: CH4

  
• Ethane: C2H6

  
• Propane: C3H8

  
• Butane:C4H10

  
• Hydrocarbon properties can change as the chain gets longer
• The shorter the carbon chain, the more runny a hydrocarbon is - the less viscous it is
• Hydrocarbons with shorter carbon chains are also more volatile (they have lower boiling points), and the more flammable it is
• The properties of hydrocarbons affect how they're used for fuels. E.g. short chain hydrocarbons with lower boiling points are used as 'bottled gases' - stored under pressure as liquids in bottles
• Complete combustion occurs when there's plently of oxygen
• The compete combustion of any hydrocarbon in oxygen releases lots of energy. The only waste products are carbon dioxide and water vapour
• hydrocarbon + oxygen -> carbon dioxide + water (+ energy)
• Oxidation can be defined as the gain of oxygen
• During combustion, both carbon and hydrogen are oxidised
• Hydrocarbons are used as fuels due to the amount of energy released when they combust completely
• You need to be able to give a balanced symbol equation for the complete combustion of a simple hydrocarbon fuel when you're given its molecular formula