C6.2

• Hydrocarbon - a compound made up of hydrogen and carbon atoms only
• Two types of hydrocarbons: Alkanes and alkenes
• Carbon can only ever have four bonds
• Alkanes are saturated hydrocarbons. Only single bonds between carbon atoms
• Alkenes are unsaturated. Double bond between carbon atoms
• If you add bromine water to alkene it goes from orange to colourless

  Alkenes are reactive

  Alkanes are not
• Homologous series - family of compounds with same general formula. Same chemical properties. Trend in physical properties.

  As alkanes increase boiling point also increases
• Covalent bond exists in hydrocarbons. When you heat the my are trying to overcome weak intermolecular forces.
• pentane has a higher melting point than ethane as it has more/stronger intermolecular forces
• Fractional distillation separates crude oil. Crude oil is heated to vapour. Fractional distillation has a temperature gradient (hotter at the bottom and cooler at the top). Fractions condense at different levels because they have different boiling points.
• Refinery gases have a lower boiling point so condense at the top. Bitumen has a high bpt so condenses at the bottom
• Smaller hydrocarbon has a lower boiling point, is more volatile, more flammable and less viscous (runny)
• Cracking is the process of breaking down long chains of hydrocarbons to make smaller more useful hydrocarbons which are higher in demand. it makes a mixture of alkanes and alkenes. conditions needed are a high temperature and a catalyst
• Complete combustion - unlimited supply of oxygen - reacts completely

  Incomplete combustion - limited supply of oxygen forms carbon monoxide
• Complete combustion always makes carbon dioxide and water
• Incomplete combustion always makes carbon monoxide and water
• In incomplete combustion less oxygen is made
• Carbon monoxide is poisonous/toxic
• Alkenes are reactive due to their double bond
• Only carbon atoms attached to a double bond will react.
• Halogenation is when an alkene reacts with a halogen
• In hydrogenation you need 150 degrees and a nickel catalyst. it reacts with an alkene to form an alkane
• Hydration is alkene with steam. It needs to be above 100 degrees and has a phosphoric acid. alcohol is formed
• In a displayed formula all of the bonds are shown.
• Polymer is a long chain molecule made up of small molecules known as monomers. only occurs with alkenes
• Methane - CH4
• Ethane - C2H6
• Propane - C3H8
• Butane C4H10
• Ethene - C2H4

  Propene - C3H6

  Butene - C4H8