An investigation into the energy value of biscuits.

Table of results for food tests:

 By looking at my table of results, I predict that the value digestive is the biscuit that will have the most energy. I think this will be because it reacted the most by turning cloudy and by showing the most grease on the greaseproof paper. It also had the most protein in the biurrets test.

Pre-Trial experiment

Fair Test:

These are the input variables that I will keep the same- size of biscuit, size of Test tube, distance between the flame and flask and volume of water. The variable that I will change is the type of biscuit.

I will measure the temperature of the water.

To check that my results are reliable I will repeat the experiment 3 times and take an average.

Experiment:

Equipment:

Bunsen burner          Measuring cylinder          Balance

Petri dish                  Goggles                            Scalpel

Splint                        Test tube             Computer (To correlate the results)

Step by step:

1. I will set up the equipment as shown in the diagram above. I will first choose the normal digestive biscuit out of the choice of three and weigh it on weighing scales in a petri dish. I will take into consideration the fact that the weight of the petri dish might affect the reading on the scales, so I will take the weight of the petri dish away from the final total.
2. I will make then draw a table to display my results in, and then take a reading of the temperature of the water at the start of the experiment and put it into the table.
3. I will light the biscuit by using a lighted splint.
4. Wait until the biscuit has burned and then take a reading of the temperature of the water and record the results in the table.
5. I will then calculate the rise in temp and add this to my table of results.

Trial results:

What was wrong with our experiment?

If we change the test tube to a flask so that it has a flat base, more of the flame gets to the water. We should also stand for the biscuit to keep the same distance. We could also put foil around the base of the biscuit to try and reflect the heat. Logits could be used instead of thermometers, as they would be more accurate. Water-less to 20c as less time to heat up-3cm more heat energy and molecules vibrate faster so quicker time to heat up.

Real Experiment

Diagram:

Step by step:

1. Cut up each of the biscuits into 3 pieces using the scalpel, then weigh them. (As in p.1 above take into consideration the weight of the petri dish.)
2. Then put the results into a table.
3. Then start logging the data with a temperature probe.
4. Light the biscuit with a lighted splint, so that it starts to burn.
5. Wait until the biscuit has burned completely and then stop the data logging
6. I will then take the logit to the computer, then save the data and then print a graph of the collected data.
7. I will repeat my experiment 3 times for each of the 3 different types of biscuit, with the 3 pieces that I cut from the biscuits earlier on.

Table of results:

Formula

I will use this formula to work out the energy for each biscuit: (Temp rise x 20 x 4.2) divided by (1000 x weight of biscuit.)

(34.53 X 20 X 4.2)  (1000 X 2.23) = 1.63 KJ

Average energy for Digestive = (0.91+1.63+2.53)  3

= 1.69

(16.73 x 20 x 4.2)  (1000 x 1.91) = 0.66 KJ

Average energy for value = (0.91 + 0.66 + 2.53)  3

= 0.87

(31.7 x 20 x 4.2)  (1000 x 2.41) = 1.69 KJ

Average energy for Low fat = (0.91 + 1.69 + 2.53)  3

= 1.08

Analysis:

By looking at my results in my bar graph and table of results I have found the biscuit with the most energy is the normal digestive biscuit. The energy was 169 KJ. The average energy of the reduced fat biscuit was 0.87 KJ. The average energy of the value digestive was 1.08 KJ.

 

My findings do support my prediction as I predicted that the biscuit with the most fats and carbohydrates would have the most energy and the normal digestive did have the most fats and carbohydrates.

Evaluation:

The quality of evidence was quite good, but this was only because of the changes we made in the trial experiment. Like changing the test tube to a flask, this meant that more flame could get to the water to heat it faster. Also by putting foil around the base of the biscuit, it reflected the heat and caused the biscuit to burn faster. Logits were a lot better than thermometers, as we got much more accurate results and could also transfer our collected data to a P.C correlate the results. The experiment could have possibly been more accurate if each of the biscuits stayed alight, instead of having to relight them. As this took heat energy away from the flask and therefore the heat wasn’t reaching the water.

Somewhere we might have gone wrong in the experiment was that we didn’t wash the flask after every experiment. The soot that coated it might have helped to absorb more heat and allowed more heat energy to reach the water.

Results:

Any odd results might have been caused by various reasons:

• Someone came into the lab- this would have meant the door opening and this could have caused wind, which might have altered our results.
• A window may have been left open, which also means that the temperature of the room was altered and wind might have blown through affecting our results.

Further work:

Further work could be to use different foods instead of biscuits- We could also use different food categories such as fruits, vegetables, or maybe ‘junk’ foods such as fast food e.g. ‘MacDonald’s’. We could also try different types of biscuit, maybe even a diabetic biscuit.

How I would do this experiment properly:

Factories use a method called oxidation. Oxygen is fed into the space around the nut. A small electric current is passed into the nut. When it gets hot enough, the food begins to combine with the oxygen. As it does so energy is released from it. The energy is heat energy. The food burns and the water heats up.

1. It is more efficient because;

There is more contact with H2O/2.

2. It is protected from people breathing on it. The flame cannot be blown out  

accidentally and it has a lot more energy.

3. The exhaust pipe ensures the maximum amount of surface is exposed for heat    

transfer, so the water is heated up as much as possible.

4. Oxygen is fed in, this means that the flame can burn brighter and longer so

can give off more energy.

5. It is properly insulated and has a lid to stop any heat escaping therefore little

energy loss and you can get the maximum results.