Total Energy Needed (To break the Bonds):
CH3OH (Methanol) + 1.5O2 (Oxygen) = Total Energy Needed
3 x 435 + 358 + 464 = 2127 (The Total Bond Energy needed for Methanol)
1.5 x 497 = 745.5 (The Total Bond Energy needed for Oxygen)
2127 + 745.5 = 2872.5 (The Total Energy Needed)
C2H5OH (Ethanol) + 3O2 (Oxygen) = Total Energy Needed
5 x 435 + 358 + 464 + 347 = 3344 (Total Bond Energy needed for Ethanol)
3 x 497 = 1491 (The Total Bond Energy needed for Oxygen)
3344 + 1491 = 4835 (The Total Energy Needed)
C3H7OH (Propanol) + 4.5O2 (Oxygen) = Total Energy Needed
7 x 435 + 358 + 464 + (2 x 347) = 4567 (The Total Bond Energy needed for Propanol)
4.5 x 497 = 2236.5 (The Total Bond Energy needed for Oxygen)
4567 + 2236.5 = 6803.5 (The Total Energy Needed)
C4H9OH (Butanol) + 6O2 (Oxygen) = Total Energy Needed
9 x 435 + 358 + 464 + (3 x 347) = 5778 (The Total Bond Energy needed for Butanol)
6 x 497 = 2982 (The Total Bond Energy needed for Oxygen)
5778 + 2982 = 8760 (The Total Energy Needed)
Total Energy Released:
Co2 (Carbon Dioxide) + 2H2O (Water) = Total Energy Released For Methanol
2 x 803 = 1606 (Energy Released From The Carbon Dioxide)
2 x (2 x 464) = 1856 (Energy Released From The Water)
1606 + 1856 = 3462 (The Total Energy Released)
2Co2 (Carbon Dioxide) + 3H2O (Water) = Total Energy Released For Ethanol
2 x (2 x 803) = 3212 (Energy Released From The Carbon Dioxide)
3 x (2 x 464) = 2784 (Energy Released From The Water)
3212 + 2784 = 5996 (The Total Energy Released)
3Co2 (Carbon Dioxide) + 4H2O (Water) = Total Energy Released For Propanol
3 x (2 x 803) = 4818 (Energy Released From The Carbon Dioxide)
4 x (2 x 464) = 3712 (Energy Released From The Water)
4818 + 3712 = 8530 (The Total Energy Released)
4Co2 (Carbon Dioxide) + 5H2O (Water) = Total Energy Released For Butanol
4 x (2 x 803) = 6424 (Energy Released From The Carbon Dioxide)
5 x (2 x 464) = 4640 (Energy Released From The Water)
6424 + 4640 = 11064 (Total Energy Released)
Overall Energy Released = Total Energy Released : Total Energy Needed
Overall Energy Released For Methanol – 3462 : 2872.5 = 1.2052219
Overall Energy Released For Ethanol – 5996 : 4835 = 1.2401241
Overall Energy Released For Propanol – 8530 : 6803.5 = 1.2537664
Overall Energy Released For Butanol – 11064 : 8760 = 1.2630137
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Pre-Test
I am conducting a pre-test to find out the best way the main test should be conducted. In the pre-test we will be using the same fuel for every test. For the first test we timed the experiment for 2 minutes and used 50 ml of water. These were the results we got.
Diagram
Method
We set up the apparatus as shown above. We weighed the burner before we lit it. We made sure that the thermometer wasn’t touching the sides of the cup. Then we lit the burner and placed it under the cup of water and set the stopwatch. We then checked the temperature of the water every 30 seconds for 5 minutes. We weighed the burner at the end of the experiment.
Fair Test
We made this experiment fair in a number of ways. First of all we conducted a pre-test to see which way we should do the main experiment. We didn’t allow the thermometer to touch the sides of the cup so it was just measuring the heat of the water. We made sure that the cup was roughly the same height from the ground. We used a different cup every time so that the heat from the previous cup wasn’t transferred into the new water we were putting in it.
Results
Methanol
Ethanol
Propanol
Butanol
We decided that 2 minutes wasn’t long to get an accurate set of results so we decided to change it to 5 minutes. We also decided that if we were to raise the amount of time the experiment would be done for we would need to increase the amount of water used because 50 ml might start to get too hot, so we decided to change that to 100 ml. Our results for this test were.
After we conducted that test we decided to put a foil tube round the experiment and a piece of foil card on the top of the tube so it was covered we just left a little gap to allow us to see he thermometer. We did this because we didn’t want the heat to escape into the atmosphere and it would give us a more accurate set of results.
Conclusion
My prediction about the larger the molecules in the alcohol the more energy being released is correct. Butanol the alcohol with the larger molecules released most energy and therefore made the water the hotter than what all the other alcohols did. Looking at my results I can see the alcohols what released least energy and most energy didn’t use as much fuel as the other ones did this can be seen below.
I can also see that the more energy the fuel releases the more heat it gives off which can be seen in the table below.
I am now going to calculate the temperature rise and then divide it by the amount of fuel used to get the temperature rise per gram of fuel used to see if there is a noticeable trend.
Temperature rise for methanol = 38.7
Temperature rise for ethanol = 55.3
Temperature rise for propanol = 56
Temperature rise for butanol = 65
