- Then place the gauze on the top of the tripod and put the small beaker with the thermometer on the gauze.
- Allow the water to heat from the spirit burner for 3 minutes and record the temperature of the water every minute, record your results.
- When the 3 minutes are over, take the water off the gauze, blow out the flame from the spirit burner and using the tongs take the spirit burner out of the beaker and measure it on the digital scale, record the results.
- Repeat the steps above for all of the spirit burners. After that put the results in a table and then graph them.
Data:
Lid – 58.3g
Spirit Burner ( Empty ) – 100.0g
Mass of Spirit burners before burning (with lid):
Methanol – 158.1g
Butanol – 162.2g
Pentanol – 160.1.g
Ethanol – 169.6g
All of the temperatures were measured in degrees Celsius and I then converted them to Kelvin by using the following formula:
K = 273 + degrees Celsius
Methanol:
Starting temperature of the water = 295 K (22ºC).
Temperature change = 20 ºC = 293 K
Original mass= 158.1g
Mass after burning = 154.6g
Q = m c ΔT
(Q = energy, m = mass, c = specific heat capacity, ΔT = change in temperature)
Energy = mass x specific heat capacity x change in temperature.
Energy = 100 x 4.2 x (change in temperature) = Joules
For the specific heat capacity of water it is 4.2 and not 4200 because grams are being used and not kilograms, so divide the 4200 by 1000. For the 100 ml of water it is equal to 100 grams because the specific mass of water (= mass/volume) is 1 (1 litre = 1 kilogram).
Energy = Specific Heat Capacity x Mass x Change in Temperature
100 x 4.2 x (change in temperature in Kelvin) = Joules
100 x 4.2 x (20+273) = 123060 J
Energy (J) = J/g
Change in mass (g)
123060J = 35160 J/g
3.5
Butanol:
Starting temperature of the water = 296 K (23ºC).
Temperature change = 15 ºC = 288 K
Original mass = 162.2g
Mass after burning = 95.2g
Energy = Specific Heat Capacity x Mass x Change in Temperature
100 x 4.2 x (change in temperature in Kelvin) = Joules
100 x 4.2 x (288) = 120960 J
Energy (J) = J/g
Change in mass (g)
120960J = 1805.37 J/g
67
Pentanol:
Starting temperature of the water = 296 K (23ºC).
Temperature change = 8 ºC = 281 K
Original mass = 160.1g
Mass after burning = 99.3g
Energy = Specific Heat Capacity x Mass x Change in Temperature
100 x 4.2 x (change in temperature in Kelvin) = Joules
100 x 4.2 x (281) = 118020 J
Energy (J) = J/g
Change in mass (g)
118020J = 1941.12 J/g
60.8
Ethanol:
Starting temperature of the water = 296 K (23ºC).
Temperature change = 10 ºC = 283 K
Original mass = 169.6g
Mass after burning = 109.1g
Energy = Specific Heat Capacity x Mass x Change in Temperature
100 x 4.2 x (change in temperature in Kelvin) = Joules
100 x 4.2 x (283) = 118860 J
Energy (J) = J/g
Change in mass (g)
118860J = 1964.63 J/g
60.5
I then compared the results of the different fuels by putting them all together into a table:
Conclusion:
The fuel Methanol heated up the water to 42ºC in a time period of only 3 minutes. Methanol has the least amount of carbons and it was able to heat the water the most. On the other hand Pentanol heated the water the lowest which was 31ºC. Pentanol is the fuel which includes the largest number of carbons and it only reached the lowest temperature of heating the water in comparison to all of the fuels.
This set of results proves that my hypothesis is wrong because I predicted that the greater the number of carbons in the fuel then the more energy would be released. However this was not the case so therefore the hypothesis of my experiment is incorrect and has been proven wrong.
During the process of the experiment there were some difficulties that we came across which possibly could have affected the results of the mass of the spirit burners after the 3 minute burning procedure. It was challenging to take the spirit burner out of the beaker because the tongs were not suitable to the size of the beaker and the beaker was very hot so therefore we could not touch it with our hands. Removing the tripod, gauze and beaker of water, so that we could blow out the flame of the spirit burner, was very time consuming. This affected our results because it was not a fair test due to the fact that not all of the spirit burners were measured directly after the 3 minutes.
Looking at the results that were recorded for the Methanol there is an obvious mistake in the recording of the mass because the original mass was 158.1g and the final mass was 154.6g. The difference between the two numbers was not very large compared to the other results that were gathered for the other fuels. Ethanol for example had an original mass of 169.6g and a final mass of 109.1g. This clearly shows that some sort of error occurred during the recording of the results for Methanol.
If I was to do this experiment again then I would measure the mass of the fuel that was inside each spirit burner instead of just pouring any amount of fuel into the spirit burner. If there was a constant mass of each fuel then it would have made it a fair test. Another thing that I would do to improve this experiment would be to take more then just one set of results in order to make sure that everything is accurate.
In conclusion I found out that a higher energy released per 1 gram means that the fuel is more efficient. Even though Ethanol has the least amount of carbons it was able to rise the temperature of the water up to 42ºC, whereas Pentanol, which has the largest amount of carbons was only able to rise the temperature of the water to 31ºC.
