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humorist-workshop
Chemistry Coursework
For my chemistry coursework I was given the task 'Comparing the enthalpy of combustion of various alcohols'. It basically means that I had to burn ethanol,methanol,propanol and butanol in spirit burners and measure the tmperature change of the water in a calorimeter suspended above the burner.
I'm not sure how to go about writing up the analysis or what to write in the risk assessment.
Have you got any suggestions?
Thanks a bundle.
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Maybe give some free advice about: School?
I think the best source of advice on this would be your teacher or instructor. It is hard to tell if he is looking for a paper, or a chart, or what. Usually teachers don't mind if you ask questions like this.
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For the analysis, first take a look at your hypothesis. Based on the chemical structure of these different alcohols, you should be able to make some predictions as to which ones will release more heat. You may also be able to look up some empirical data about the enthalpy of combustion for each of the given alcohols. If alcohol A, for example, has 1.5 times the enthalpy of alcohol B, it would be realistic to expect about 1.5 times as much energy to be transfered to the water. You can measure the energy transfer by recording the change in heat of the water over time, and by comparing that to the mass of water being heated. Ensure that you are using an equal number of mols of each alcohol: this may be part of the experiment.
For the risk assessment, I'm used to hearing the phrase in two different contexts. The first context is physical risk: you're messing with combustible alcohols. The other context (which I think is the one you mean) is the risk of skewing your experimental results. The most common sources of experimental error are poor measurement and improper recording of experimental results. You could, for example, measure the alcohols by volume instead of factoring in molar weight and ensuring that the samples had identical alcohol content. You could fail to record the starting temperature of the water prior to each experiment. You could fail to ensure that the same amount of water is used, or that the water samples start off at the same temperature (ie. room temperature instead of boiling). The spirit burner should cut down the heat transference to other things besides the water in the calorimeter.
Good luck!
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