Heat Energy Experiment Aim: To measure the heat energy released in a burning fuel.

For accuracy, the maximum temperature of the water was measured. The fuel was not left for a long time as the water would evaporate and the bottom of the test tube was cleaned in order not to interfere with the heating process.

To make it a fair test, the time taken of different fuels to burn could be measured. If this happened, the apparatus should be properly washed, everything re-weighed and re-measured, and the thermometer left to cool.

Results:

(Averages)

Observations:

The results were averaged out from 2 repeats (each) for improved accuracy.

Some observations were taken during the experiment:

• The firelighter burnt for a lot longer than the ethanol.
• The firelighter’s flame was a lot stronger and created more soot than the ethanol’s.

Calculations:

Heat energy produced =

 Mass of water x specific heat capacity x temperature rise of water

Ethanol

20 g x 4.2J x 13.5ºC = 1134 J

                             

                                      1.134 x 100

                                                   1.43        = 79.3 kJ/100g

                                     

Fire Lighter

20 g x 4.2J x 24.5 J = 2058 J

                                     2.058 x 100

        1.39                  = 148.1 kJ/100g

                     

        

Other Observations

The calculations show that the fire lighters overall produced more heat energy than the ethanol. These results match the temperature rise, as the fire lighter’s was higher, but do not match the mass, as in all occasions the ethanol’s mass was greater.

Conclusion

This experiment shows that the fire lighters produce more heat energy than the ethanol. Before the calculations were made, this was reasonably apparent due to the higher rise in temperature by the fire lighters.

The results were fairly reliable. Human error could have been involved with measuring, although precautions were taken for this. Some other possible errors could have been:

• The fact that the flame didn’t always go to the test tube.
• Energy was lost in the air, not going directly to the test tube and giving inaccurate values.
• Although the watch glasses were cleaned, some excess weight was left on for the repeats of the experiment.
• The results aren’t very reliable due to the fact that the ethanol might not have been pure, having some chemicals added to it.

Possible improvements could be:

• Place things around the experiment for constant flame.
• Lower the test tube so less energy is wasted.
• Use different test tubes and watch glasses each repeat for more accuracy.
• Repeat the experiment at least 5 times for improved and more accurate averages.