Find out the amount of energy released when burning different alcohols.

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Chemistry Coursework – Combustion of Alcohols


 To find out the amount of energy released when burning different alcohols.


 I predict that octan-1-ol will release the most heat energy. This is because there is more bond energy in that molecule than the other alcohols.

 Within a molecule there are bond energies that are holding the atoms together. When the fuel combusts a chemical reaction takes place, this breaks the bonds, this requires energy, and makes new bonds this gives out energy. The energy differences between the two tell us how much energy was given out or taken in. We can show this on a graph.


 In this investigation I will be burning alcohols to heat up a can of water. I will be burning seven alcohols, Ethanol, Propan-1-ol, Butan-1-ol, Pentan-1-ol, Hexan-1-ol, Heptan-1-ol, Octan-1-ol. The aim is to find out how much energy is produced when burning these alcohols. ‘An alcohol is a series of organic homologous compounds, with the general formula Cn H n + 1OH´. Alcohols react with oxygen in the air to form water and carbon dioxide.

 The reaction that is involved in burning alcohols is exothermic because heat is given out. Form this reason the reactant energy is higher than that of the product.

 The energy is given out when forming the bonds between the new water and carbon dioxide molecules. The amount of energy produced by such exothermic reactions can be calculated by using the formula Mass of the substance x rise in temp x SHC (specific heat capacity). The specific heat capacity is the number of joules required to heat one gram of water by 1ºC. I chose to use water because it is safe, easily found, and has a reliable specific heat capacity of 4.2.

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 The bonds that are formed in an exothermic reaction can be of two types. The first could be ionic, where a metal is produced. Ionic bonding involves electrons transferring from one atom to the other consequently leaving an electrostatic force between them. The other form of bonding is covalent where atoms share electrons to complete their outer orbit. An example being Methane where four hydrogen atoms each share an electron with a carbon atom.

The variables that must be controlled are:  

  • Mass of alcohol
  • Mass of water
  • Amount of wick on burner
  • Type ...

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