Fair test
We will try to have the same conditions for each test. We will do this by using the same amount of water [15ml], which is around the same temperature as all the other test tubes before the lighted food is put under them.
We will try to use the same amount of food each time we burn it.
Safety
I will wear goggles to protect my eyes when working with burning food and keep my fingers well away from burning food.
Prediction
I predict that the biscuit with the most energy will be the oat and wholemeal because it has the highest carbohydrate levels and the highest fat content by 14.2 g which probable means it will have the most energy in it.
Results
Analysis Calculations
As the biscuits differed in mass, I need to work out the energy produced per gram using the following calculation.
Energy/g [in J] = vol of water heated x temp change c x 4.2
Change of mass of biscuit
Summary
Rich tea - 1410.447761 Average =943.00341623
- 766.4233577
- 652.173913
Sponge - 597.9710221
- 1063.555114 = 798.5839568
- 734.2257343
Oat - 492.8292047
- 724.8953975 = 608.8623011
- 5387.828162291
Analysis
From this experiment we found that the oat biscuits should have had the most energy but our test results were wrong , they supposedly showed that the Rich Teas had the most energy and then the sponge biscuits then the oat biscuits. As the oat had the most fat and carbohydrates, it makes sense the biscuit will have the most energy because you get energy from those things. This means the prediction was right because of the fact that the oat and wholemeal was the one with the most energy. Most of our results agree with this but some were anomalous because the biscuit caught fire very quickly which meant the temperature went up considerably and some biscuits hardly burned at all.
Evaluation
I thought the test was good because it was fairly accurate for the temperature results but if you got an anomalous result like we did for the last oat biscuit then your average was not very accurate. Our result was anomalous because the biscuit suddenly caught light and would not stop burning but the other two oat biscuits didn’t light very well so we got very different results e.g. for the anomalous result we got 5387.828162 J but the lowest result for the oat biscuit we got was 492.8292047 J so there was a big difference in one of our test results.Then as the other two also differed from each other we could not see which of our test results was right. Therefore, I think if we had had more time to do, perhaps 5 tests for each food then we would probably get a more accurate test result.
The temperature results weren’t too inaccurate because as long as you stirred the water to get an equal temperature at the bottom and the top then the temperature was accurate unless it boiled because it lost heat when it boiled. This presumes the scale was read correctly.
I don’t think our results were good enough to support our conclusion because the anomalous result we got for the oat biscuits was lower than all of the others when technically it should have been higher than them and had the most energy in it.
I think we could have improved the experiment by making small changes, for example, we could have been more organised and kept our biscuit together better because when you burned it, it went soggy and bits dropped off so when we weighed the remaining part of the biscuit, part of it was missing so the result was slightly wrong. We may have spilt some of the water when we were putting it in the test–tube or putting the test tube in the clamp. When we were burning the food it didn’t always just heat the test tube but heated the air around it as well so the water could have been hotter if we had just heated the water. We lost some heat from the water because some of the biscuits were difficult to keep alight so some times we had to go back and relight the food 2 or 3 times, in the time it took us to relight the food it could have cooled down by 1-3 degrees. I think the way we held the food was inaccurate because when the biscuit went soggy, it fell off the mounted needle and on to the bench and bits dropped off. It was difficult to keep the food burning as it kept falling off and, if it did set alight fiercely, it set the handle on fire so the wood burned as well as the biscuit.
I think the best thing we could have used would have been a calorimeter because it would have given us the test results more accurately than we can do them and it would be a lot quicker to do 10 tests for each food in the time it took us to do three.