Results
The final results highlighted in blue are the results which I think may have gone wrong in some way, I will not disregard them in the working out of averages because if I did then there wouldn’t really be enough results to make a fair conclusion.
The average results are:
Propan-1-ol =30+27+38
3 = 31.6ºC
Propan-2-ol =28+38+29
3 = 31.6ºC
Butan-1-ol =24+31+33
3 = 29.3ºC
Butan-2-ol =29+30+31
3 = 30ºC
As you can see propan-1-ol and propan-2-ol are exactly the same and butan-1-ol and butan-2-ol are also pretty close.
Graphs
As you can see from the graphs the lines are ending at nearly the same place each time clearly showing that they are giving off more or less the same amount of heat to the water.
Analysis
Specific Heat Capacity e=mcθ
Water – 4.2j-1K-1
Copper – 0.38j-1K-1
Glass(thermometer) – 0.67j-1K-1
Mass e=mcθ
Propan-1-ol – 2mls = 1.37g
Propan-2-ol – 2mls = 1.51g
Butan-1-ol – 2mls = 1.42g
Butan-2-ol – 2mls = 1.66g
θ= Temperature change e=mcθ
Propan-1-ol
e=mcθ
Water
e = 50 x 4.2 x 31.6 = 6636j
Copper crucible
e = 75.29 x 0.38 x 31.6 = 904j
Thermometer
e = 11.29 x 0.67 x 31.6 = 239j
e = 7779j
Propan-2-ol
e=mcθ
Water
e = 50 x 4.2 x 31.6 = 6636j
Copper crucible
e = 75.29 x 0.38 x 31.6 = 904j
Thermometer
e = 11.29 x 0.67 x 31.6 = 239j
e= 7779j
Butan-1-ol
e=mcθ
Water
e = 50 x 4.2 x 29.3 = 6253j
Copper crucible
e = 75.29 x 0.38 x 29.3 = 838j
Thermometer
e = 11.29 x 0.67 x 29.3 = 222j
e= 7313j
Butan-2-ol
e=mcθ
Water
e = 50 x 4.2 x 30 = 6300j
Copper crucible
e = 75.29 x 0.38 x 30 = 858j
Thermometer
e = 11.29 x 0.67 x 30 = 227j
e= 7385j
Propan-1-ol= 7779j
Propan-2-ol= 7779j
Butan-1-ol= 7313j
Butan-2-ol= 7385j
The heat energy transferred to the water may have been just about the same but as it shows here the total energy transfer is a bit different (only on the butanols). Butan-2-ol gave off more energy than Butan-1-ol. Strangely the propanols gave nearly exact results as each other (apart from a few decimal places).
You could also work out which should give off the most energy by using moles.
Propan-1-ol
H – C – C – C – OH
Propan-2-ol
H – C – C – C – H
Butan-1-ol
H – C – C – C – C – OH
Butan-2-ol
H – C – C – C – C – H
As you can see 1 mole of butan-1 or 2-ol weighs more than 1 mole of propan-1 or 2-ol. This means that the ‘butanols’ will require more energy to get them started, (this is because it has to break more bonds) but they will give off more energy than the ‘propanols’ when the reaction is finished. For some reason this did not happen in our experiment.
Evaluation
Overall I think our experiment went very well nothing went horribly wrong except for a few odd results. I think our odd results may have came from the atmosphere around the experiment like a door or window opening, but It could have also been down to human error;(wrong measurements).
The set up of our experiment was okay but it could have been a lot better. The chimney we used was too fiddly, and it prevented us from seeing when the flame had gone out. I think that if we made it out of some kind of transparent material the experiment would have gone a lot better.
To make the test fair we used the exact same amount of water and alcohol each time and made sure that everything was set out in the same place each time. In our preliminary work we found that using 100mls of water was too much. The alcohols weren’t heating the water up enough to get good results. On the actual day we decided to use 50mls of water and found it to be a lot more accurate.
I think that our results were very reliable and sufficient to support the conclusion, we had a range of results all very similar that were averaged, nothing was really wrong with them at all. All though my prediction was wrong I feel that I now learned something new which is a good thing. I could do another experiment to back up my conclusion, I could use different alcohols like butan-1+2-ol and pentan-1+2-ol. Doing this experiment as well would back up my theory a lot.