Method - Comparison:
I will then compare these two fuels by heating them until they get to a certain temperature noting down the time every time the temperature increases by 10°C in order to form a scatter graph using line of best fit.
I will use step one and most of step two from the preliminary test (first of all, I will make sure I take all of the safety precautions, I.e. tie back long hair, use goggles and make sure the room is well ventilated. Secondly I will set out the apparatus and get all the equipment from the list (shown on the previous page). Using the measuring cylinder, I will put 20cm3 of distilled water into a boiling tube,) I then heat the water using the first fuel until it rises to 100°C, noting the time every 10°C starting from 20°C. I then repeat this test twice more for this fuel and three times for second fuel. After all the tests I find out the average time of the three tests for each temperature and note them down.
Results-preliminary:
Conclusion:
To make sure your results are accurate, you would usually do three to five tests, but as the class were doing the test separately in groups of two or three each group put their results on the board in a tally, and the two fuels that produced the most energy were ethanol and firelighter, so I have tested those two against each other three times, found the average of each time and have come up with the following results.
Results for ethanol and firelighter:
Table of results for ethanol:
Table of results for fire lighter:
Conclusion:
To conclude; I think that ignoring the result taken under 80ºC, ethanol is more of a steady line of best fit, but did not double with a set amount of time therefore also did not increase 10ºC every 10 seconds so it was not directly proportional. whereas firelighter has more of a curve of best fit, which after reaching 70ºC increases to a steeper line of best fit. But still did not double with a set amount of time therefore also did not increase 10ºC every 10 seconds so it was not directly proportional.
As you can see from the table above, when drawing my line of best fit I left out the result for ethanol under 80ºC (circled) as this result was an anomaly. I thought it may have been noted in the wrong place, or the stopwatch had been stopped or started to soon or too late, or maybe even the windows being left open and blowing the flame! But after further analysis I discovered that the anonyms reading came from miscalculation when working out the average time taken to reach 80ºC for ethanol, as you can see the results for the three tests taken for 80ºC are displayed above showing that none of them decrease lower than 161ºC.
Therefore the average could not be 123ºC.
Taking all the above into account and if we ignore, that different quantities of each fuel were used, it can be concluded that the firelighter was the fuel with most energy.
Evaluation:
To ensure safety/accuracy the windows were shut for the tests, but doors left open, as we needed good ventilation.
Evaluation-improvements:
To improve the results accuracy for future experiments, I could use a calibrator to make the test a lot more accurate. Which would stop any heat escaping by shielding the flame and stop any wind from coming in. Also, to improve the accuracy of my test results, I could use the equation, 84 * X°C to calculate the amount of (J) transferred to the water. I got this equation, from information in a science book saying it requires 4200J to heat up 1 kg of water by 1°C so then to change that to ml as my investigation was in ml I know that 1 kg = 1L of water which =1000 ml, so then 4200/1000 = 4.2, Then x 20, as that’s how many millilitres I used for my experiment, which = 84 then to get the (J)
I do 84 x the amount of degrees the water had risen to = the amount of energy transferred to it in (J)!
Another way to improve the accuracy of the experiment would be to improve the fact that unspecified amounts of fuel where used, as we did not weigh the fuel therefore it was not a completely fair experiment. For instance it can be safely assumed that if we used twice as much ethanol, we would get a flame twice as big. So the water would reach 100°C much quicker and probably in half the time. Although you will need to do a separate experiment to prove this assumption. If this experiment is repeated, I recommend that the same amount of each fuel is used and the experiment continues until all the fuel runs out. To make the experiment even more fair all the fuels should be at the same temperature at the start.
Sources:
Letts, GCSE Science.
