This is a diagram of how I would do the experiment.
Safety precautions
As this experiment has heating alcohols it is essential to wear goggles to protect the eyes. Great care must be taken when handling the alcohols. A lab coat might be good idea to wear form spillage of the alcohols to clothes. It might be safer if you had a heat proof mat. If you spill the alcohol on your hands it is essential to wash with soap as its smell is bad for your health. If you drop the burner on the floor it is important to keep the matches and flames away because the floor could catch fire from the alcohols.
Fair test
In this experiment I have measured the mass of the burner and the alcohols being heated at the start and at the end. The amount of water, 100g is measured using a measuring cylinder every time. The height of tin can and distance away from the burner is a major factor they would have needed to be the exactly same every time. The alcohol burner must be the same one used each time you repeated the test. The tin can has to be changed every time you finished with one experiment as if you did it again the temperature will be hot and not fair. The alcohol burner the rope inside has to touch the liquid if it did not it would not work.
This experiment is exothermic reaction it gives heat energy. The aim is to predict the heat of combustion for heptanol, the alcohols have carbons and hydrogens the number of carbons as the hydrogens increase. A more reactive element displaces a less reactive element from its compound. The more reactive one joins to other elements with strong bonds.
When you burn the ethanol burner you expect that at the end when the results are done that the mass of ethanol used will not be much because the carbon and hydrogen bonds in ethane is 2 carbons and 6 hydrogens so not much but if you burn octanol you expect that the mass of octane to be a lot because the it has 8 carbons and 18 hydrogens. Also, the molar mass is lighter in ethane than octanol so I predict that the lighter in molar mass the more efficient the alcohol.
Analysis
Conclusion
As you can see in the results I have done it three times because if you only did it once you would not get a reliable result because you won’t be sure which one is reliable one, so if you do it three times you can guess where around the correct result is. The experiment is neatly and safely laid out and that it is easy to take and record measurements. The experiment required more than one person and we had to work effectively. In the first lesson my colleague wasted a lot of time but in the next lesson we worked very hard doing experiments as I would do the butanool and he would do the octanol. The relationship is the more mass of alcohol is used when there is less carbons.
My predictions were that when there are more carbons on the alcohols it will use less mass of the alcohol so heptanol would be close to octanol so by looking at the graph I can roughly see what the mass of alcohol would heptanol. The butanol experiment is wrong because when we did the experiment the burners rope inside was not touching alcohol which would definitely had effect on the outcome of the result. From the graph I have found that the mass of heptanol used would be a round 0.6g by looking at the graph. In the graph there would have been a smooth curve but the butanol experiment when the rope of the burner was not touching the alcohol this probably effected the graph otherwise it would have been a smooth curve.
Evaluation
The experiment was accurate but we only had time to do three alcohols if we had time we would have done at least another couple to make the graph have many points to make it more accurate. The accuracy normally depends upon the type of equipment we used, and how easy it was to take the measurements. Some things are difficult to measure accurately when they are changing quickly. The accuracy may be different over the range of results taken. The most obvious mistake was the butanol burner because when we were doing the experiment the rope inside did not touch the alcohol properly. This is equipment error. Also, the distance between the calorimeter and the burner we just did that part with instinct because we were not sure, so this could and did affect the results this is human error.
The results are reliable because I did the experiment three times and the results were similar but the results could have been affected by the errors made. The method of the experiment is reliable because the method is easily carried out and the equipment was not broken or any think but there are one or two the distance between the calorimeter and burner and when the alcohol did not touch the rope which was burning. The results were not hugely reliable because firstly, the series of alcohols were ethane, butane and octane. Just three was not really that reliable also, the butane experiment was equipment error or human.
If I could repeat the experiment I would find out more about the heat of combustion because it was quite difficult to understand. Understand the key factors more and sort out the variables. Make sure I understand the essential science behind the investigation is the key to obtaining high marks. I could make a plan table. I would like to improve my prediction a prediction is a scientific model, including Higher Level science knowledge, that describes what should happen and why it should happen. In most experiments the prediction will also be quantitative. I should know what will happen because of the trial experiments I have carried out. I would like to use more science words and use them correctly.
The experiment could have been repeated or I could have done more alcohols so my graphs could have more points. More repeats of another alcohol would improve the reliability of the evidence. The teacher could have explained the work more and repeated the important factors. Also, with more equipment we could have done it quicker because sometimes we had to wait for another group to finish it. Better equipment would have made the results more reliable because some equipment could be broken when we carried out the equipment. Altering the value of one or more of the control variables may lead to an increase in the reliability of the results. Better monitoring and control of variables could also lead to an increase in the reliability of conclusions.
Extending the experiment another variable to experiment you could change the heating of water to heat acid or maybe something which is safe you could find, if the alcohols use more of it for different substances. Another is that you can change the calorimeter to something more stronger like steel or iron. Also, this is dangerous I think but mix some of the alcohols and do the experiment.