Ethanol
Propanol
Although the experiment was carried out in a careful and sophisticated manner, there were some irregularities in the procedure. Theoretical results are covered in the planning, but the actual results were affected by several factors. For instance, there was a four-centimetre gap in between the conical flask and the crucible, where heat could be lost to the surrounding air. This will have affected the results.
To investigate the heat outputs of fuels
Evaluation
To carry out this experiment, we used a standard (but fairly inaccurate) procedure, where much of the heat that would contribute to our readings was lost to the air. This was because we left a four-centimetre gap between the crucible and the base of the conical flask. This, of course, affected the results.
For instance, on our first methanol test, there was a temperature change of only six degrees centigrade, as opposed to twenty-four degrees on our second test. This vast difference between the two was probably caused by the loss of heat to the air in the four-centimetre gap between the crucible and the conical flask. Although there would have been heat loss to the air in the second test as well, there may have been objects present around the equipment after we did test one, or during test one there may have been an increase of activity around the equipment that didn’t occur during the other tests (for example, people walking past, objects on the work surface being moved, etc.). If I was to do the test again, this is one thing I would try to avoid.
I would also decrease the gap between the crucible and the conical flask if I were to do the test again, to reduce loss of heat to the air. Loss of heat could also be minimised by performing the test in a more enclosed area such as a fume cupboard.
Apart from the anomalous result in test one, I believe that the evidence obtained is reliable enough to conclude that propanol has the greatest heat output of the three fuels tested. Although the numerical results are not anything like as high as theory suggests, the order of heat output is the same as theory suggests. If conditions are kept stable (in surroundings) then this order should always be the same when this test is performed.
To improve accurate readings, I would suggest that more tests should be done for each alcohol (for instance, five instead of two). This would also iron out fluctuations in stability of evidence caused by anomalous results. To improve reliability of tests, keeping the initial mass of the crucible the same each time could make a difference.
To conclude my evaluation, I would say that evidence obtained is reliable enough to prove my prediction that propanol has the highest molar heat output or H.
To investigate the heat outputs of fuels
Analysis
Methanol
Ethanol
Propanol
There were very close similarities in the final mass of the fuels, perhaps due to their H properties, and to the initial mass properties.
There were also similarities in the mass of fuel burned each time, and this went down by a small amount for each fuel (due, I suspect, to the difference in quantity of fuel used each time). However, this similarity in mass of fuel burned each time does not affect the heat output equations, as that is affected by the temperature change.
Proving my prediction that propanol would have the greatest heat output, the results (when displayed in a bar chart) escalate in order of methanol (the lowest heat output) to propanol (the highest). I also made predictions on the actual heat outputs of each fuel, and the obtained results (for ethanol and propanol, at least) proved to be quite a lot less than my predictions.
To conclude my analysis, despite the inaccurate results caused by loss of heat to the air, propanol still proved to have the greatest heat output of the three fuels tested.
