Now I will be ready to commence the experiment. I will light the fuel and start the stopwatch. After 120 seconds, I will stop the burning and record the temperature of the water. I will also record the mass of the alcohol again.
Below is a diagram showing the setup of my experiment:
After having now done the experiment, I have obtained the following results. These are shown below in the table.
From my results I want to be able to calculate the amount of joules of energy produced by each alcohol. To do this I will need to use the following formula:
Q = mcΔt
Where Q = joules
M = mass of water (100)
C = specific heat capacity of water (4.18)
ΔT = change in temperature
I calculated the joules of energy produced by each fuel. Essentially (m x c) was always equal to 418. However the change in temperature was always different. It was calculated by simply taking away the initial temperature from the end temperature.
For example:
Butanol:
Q = (100 x 4.18) x (48 – 24)
Q = 418 x 24
Q = 10032
To make it easier, I will measure the energy in kJ (kilo joules). So Butanol produced 10.032 kJ of energy.
After having calculated all the results, I added the value of Q per each fuel to the table like so:
So from this table I can see that the best fuel from this selection based on a time span of 2 minutes is Propanol, as it produced 14.212 kJ.
But this does not necessarily make it the best fuel. It does not mean it is efficient. I want to see how efficient each fuel is per gram.
To do this I must simply divide Q by Δ Mass. For example:
Butanol:
Q = 10.032
Δ Mass = 1.3
10.032 / 1.3 = 7.716923 Kj per gram
I will write this as
Q / Δk = 7.716923 kJ/g
So now I can add another column to the table.
As you may have noticed, I have written the results for Q / Δk to 3 significant figures so as to keep the results shorter and easier to work with.
Now what we have from the table is the most time efficient and weight efficient fuels.
Amazingly, Propanol is the most time and weight efficient fuel. In fact, none of the fuels changed position in how efficient they were. For both criteria, the fuels were ordered as follows:
Best: Propanol
Pentanol
Butanol
Methanol
Worst: Ethanol
Yet, is this all I can find out about the fuels? To be honest, the answer is no. I would have liked to measure the amounts of carbon dioxide emitted by each fuel, and judged which was best for the environment per gram of fuel used.
Moreover, it would have been good to also compare each fuel to its price, and to see which fuel was most cost effective.
In terms of the practical part of the investigation, I am confident that the experiment was carried out fairly and properly, as my results seems to be solid. However, there is always room for improvement, and I think that if I used more accurate equipment, and repeated the experiment more times, my results could have been marginally more accurate.
