To Show How the Volume of Fuel Affects the Energy Output In the Form of Heat

1x Boss

1x Clamp

1x Tin Can

1x Heatproof Mat

1x Crucible

31.5mls Fuel(Ethanol)divided into:-

3x 0.5mls

3x 1mls

3x 2mls

3x 3mls

3x 4mls

15x 100mls Tap Water

1x Thermometer

Apparatus Diagram

Method

I plan to use the "volume/mass of fuel" variable to prove whether the volume/mass of fuel affects the energy output. I chose this variable because it seemed to be a useful thing to learn and know about.

What I am going to do is setup the apparatus so that the crucible is underneath the tin can which will be suspended by the clamp which is connected to the stand by a boss. I will then fill the can with 100mls of tap water. Then I will place a thermometer into the water. While the thermometer is readjusting to the temperature of the water I will place the crucible on the scales and reset them so they read zero, then I will put either 0.5, 1, 2, 3 or 4mls of ethanol into the crucible and record it's mass. I will repeat each volume/mass of fuel three times which means I will have 15 experiments to do. Once I have got the fuel I will put the crucible directly underneath the can. Then before igniting the fuel I will take the temperature of the tap water and record it. Once this is done I will ignite the fuel and wait for it to completely burn out. Immediately afterwards I will take the temperature of the now heated water and record it.

The reason I will be measuring the temperature of the water is because when the reaction takes place heat is given off from the bonds forming so if I measure the temperature for each volume/mass of fuel it will show me that volume/mass of fuel affects the energy output.

CH3CH2OH + 3O2 ??Combustion??? 3H2O + 2CO2

Ethanol + Oxygen ?Combustion??? Water + Carbon Dioxide

Fair Testing

I will make the experiment fair by making sure everything apart from my variable, which is "volume/mass of fuel", is kept the same.

The things that must be kept the same are volume of water in can, the distance from the table to the base of can, using the same height crucible every time, using the same scales every time and always re-filling the can with different water.

I think most of these points are fairly self explanatory except for the "height of the crucible" being kept the same, this is because if you use a higher crucible the accessibility of air to the fuel may be reduced, and so if you use a lower crucible the air accessibility will be greater thus giving less incomplete combustion.

I kept the volume of water the same by using a measuring cylinder. The distance from table to can I kept the same by measuring the distance between it each time. The only other thing that is important is that I re-filled the can every time so the starting temperature was always pretty much the same every time, although being a few centigrade out would not have made a great deal of difference as it was the temperature change that we were most interested in but if it had been a lot different it probably would have affected the results a lot.

Results

Simplified Results With Just Temperature Increase

Drawing Conclusions

We have found out that a greater volume/mass of fuel will result in more energy being produced and given off.

I conclude that if you have a greater volume/mass of fuel you will get more energy given out . This is because when you have a greater volume/mass it contains more bonds which are there to formed to give off energy. This is explained in greater detail in my prediction which shows that my prediction was correct. This theory is backed up by my results which show that when there was a greater volume/mass there was a greater rise in the temperature.

Evaluating Evidence

The evidence seemed to be pretty accurate apart from one anomalous result which was on the third attempt with a volume of 3mls(it is circled in red on the small results table). The result I got was 20 C. The reason this was strange was because the result before it was 22 C which means that less energy was given off for 3mls than 2mls.

This anomalous result may be due to inaccuracies in the preparation of the apparatus and faults in the apparatus. These may include incomplete combustion due to lack of oxygen, inaccuracies in the measuring of the water and the fuel, misreading of the thermometer, faults in the can for instance two different cans may have different thickness' so the thicker one would have more difficulty absorbing energy and also the bases of the cans had carbon deposit buildup from other experiments that had had incomplete combustion which also made it harder for energy to be absorbed.

There was one or two things I noticed during the experiment, one of these was that the lower volume's of fuel burned more efficiently than the greater volumes, I noticed this when the larger volumes burnt with a orange flame for a lot longer, whereas the lower volumes burnt most of the time with a blue flame. This is most likely to be because the larger volumes try to burn a lot faster but as there was not enough oxygen it could not burn completely efficiently.

Some things I would have liked to have changed are the apparatus because this is probably where most of the inaccuracies came from for instance the problem with the tin can, which I explained earlier. Instead I would liked to have used a glass beaker which I would have used every time but would have cleaned the base every time.

I would also liked to have used more accurate measuring equipment because there must have been quite a lot of inaccurate measurements that I made. Another thing I would liked to have been able to use was a vacuum cupboard which I could have filled with oxygen to prevent incomplete combustion. Also I would have liked to have used a electric thermometer which would have been much more accurate.