Investigating the Dfference in Enthalpy of Combustion for a Number of Alcohols

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Investigate the difference in enthalpy of combustion for a number of alcohols Enthalpy I am going to investigate the difference in enthalpy of combustion for a number of alcohols, the enthalpy of combustion being the 'enthalpy change when one mole of any substance is completely burnt in oxygen under the stated conditions'. I will be attempting to find how the number of carbon atoms the alcohol contains effects the enthalpy change that occurs during the combustion of the alcohol. Method I plan to measure the enthalpy change by burning the alcohol, using a spirit burner, I will then use the heat produced during the combustion of the alcohol to heat 100ml of water that will be situated in a copper calorimeter directly above the burning alcohol. The calorimeter is made of copper as copper has a high thermal conduction value, this basically means that it is a good conductor of heat so a lot of the heat the copper receives will be passed on to the water which I am then able to measure. During the experiment I will be taking a number of measurements, I will firstly take the initial temperature of the water and initial mass of the alcohol I will then burn the alcohol until an increase in temperature of 20oc has occurred in the water I will then reweigh the alcohol. The measurements [Mass of alcohol burned (g), Temperature increase (oc)] will tell me what mass of alcohol is used during combustion to cause the temperature increase of 20oc in the water, I can then work out the energy released per mole and compare these values and see which has the highest enthalpy of combustion. I will need to repeat my experiment a number of times and take an average so I am sure of an accurate result. The set up of the apparatus as you can see is v... ... middle of paper ... ...s within the alcohol affects the enthalpy of combustion. I did have an idea on how to further increase the accuracy of my results but I did not have time to put in to practice. I thought that I could make something that directed more of the heat produced towards the apparatus. A sketch of it is shown below. This would keep more of the heat produced during combustion close to the calorimeter so more is absorbed. Lining the reflector with silver/ shiny surface would also mean a lot more of the heat is kept in the apparatus so that I am able to measure it. There are other aspects of the enthalpy of combustion of alcohols that I could have also investigated. Firstly I could have looked into whether the position of the OH group within the molecule effects the enthalpy change and also whether branching within the molecule also has any effect on the enthalpy of combustion.

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