C7~Organic chemistry

• Hydrocarbon= Compound that only consists of hydrogen and carbon atoms
• Alkane= Hydrocarbons with single bonds between the carbons-saturated hydrocarbons


  Alkenes=Hydrocarbons with double bond between two carbons- unsaturated hydrocarbon
• Homologous series: a family of hydrocarbons with similar chemical properties who share the same general formula. 


  -Have similar chemical properties

  -In series that they differ by a CH2 unit

  -Have the same general formula
• General formula for alkanes is CnH2n+2

  General formula for alkenes is CnH2n


  General formula for alcohol is CnH2n+1OH

  General formula for carboxylic acid is CnH2n+1COOH
• Complete combustion= when a fuel is burnt in excess oxygen. Burning any hydrocarbon this way oxidises its carbon and hydrogen atom, producing carbon dioxide and water. 


  Ethane + Oxygen -> Carbon dioxide + water.
• How do we test for the presence of Carbon dioxide?

  • Bubble gas through limewater - if co2 is present the limewater will turn cloudy.
• Incomplete combustion= less oxygen is available at the start of the reaction, meaning solid carbon or carbon monoxide gas can be produced. (soot)


  Dangers of soot= Blocks boiler jets meaning less energy is released.

  -Causes health problems like lung damage and

  breathing problems

  Carbon monoxide= colourless cannot be seen or smelt

  -Binds to haemoglobin in RBC, which reduces the

  volume of oxygen carried. (Hypoxia)
• Crude oil= mixture of hydrocarbons, meaning we can separate the different hydrocarbons using fractional distillation.


  Fractional distillation= the different hydrocarbons have different boiling points- the one with the lowest will evaporate first.
• How does different hydrocarbons have different melting + boiling points?

  As the carbon chain increases in length, the boiling point increases because there are strong forces between molecules. (intermolecular forces)
• Cracking= is a process of breaking down long hydrocarbon chain molecules into smaller, more useful molecules.

  -thermal decomposition reaction that requires the use of a catalyst.

  Importance of cracking- more demand for shorter chain molecules.

  - reduced amount of long chain molecules.