Energy changes
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How do I find the enthalpy changes of combustion of alcohols so that I can draw conclusions about how these values are affected by their molecular structure?
This is a standard experiment that is covered in most text books. See the Nuffield Students book 4th edition pages 154 to 157.
Always carry out a risk assessment before starting practical work.
An outline of the experiment is as follows.
Set up a series of identical burners (bottles with wicks) each of which has a different alcohol. Weigh the bottle before and after burning some of the alochol to heat a measured volume of water held in copper calorimeter. Measure the temperature rise of the water and calculate the energy needed to bring about this temperature rise.
Then find the amount of energy produced if a mole of each alcohol had been burnt. You will need to think carefully about the evaluation of the data, as there are many reasons why the results might not agree with the data book.
Risk assessment
Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the risks. You must have these approved by those in authority in your school or college laboratory. Do not rely on what is said on this website.
For further guidance see our tutorial on Risk Assessment.
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updated: 22 August 2003
