The aim of this experiment is to investigate the combustion of various alcohols. The alcohols will be burnt to heat up a test tube of water, I aim is to find out how much energy is produced when burning the following alcohols: Methanol, Ethanol, Propanol, Butanol, and Pentanol. Any form of burning is an exothermic reaction (heat is given out), this means that the reactants energy is higher than that of the product. Alcohols react with oxygen in the air to form water and carbon dioxide.
When bonds are broken, energy is absorbed by the system (endothermic) and when bonds are formed, energy is released (exothermic). When alcohols are burnt, the reaction is always overall exothermic, therefore, more energy is being released than is being consumed.
Thus, my prediction is that each alcohol will burn exothermally and therefore the temperature of the water will rise.
The larger the alcohol molecule, the more bonds will be broken and formed, and therefore the more heat will be produced, so I think that Methanol will be the alcohol to combust the least, followed by Ethanol, Propanol and Butanol, then finally Pentanol, combusting the most.
Before carrying out my final experiment, I have to carry out a preliminary experiment, to determine the most efficient method to use, and on what scale.
My preliminary results enabled me to decide on 30 degrees as a suitable water temperature change, as this allowed a large enough change in mass of the alcohol, but was not too time consuming. It also helped me decide to experiment with each alcohol twice, this will ensure accurate results just one could be unreliable.
* 5 Alcohols, Methanol, Ethanol, Propanol, Butanol and Pentanol.
* Test tube
* Draught preventers (chemistry books)
* Heat proof mat