Co-ordinated Sciences

Comparing Energy of a Peanut, a Banana chip and a Potato Chip

Aim: The aim of this experiment is to compare energy stored in peanuts, potato chips and banana chips.

Background Information

Food energy is the amount of energy in food that is available through digestion. The energy in food can be measured by seeing the rise in temperature of water by burning the food and then using the specific heat capacity of water to see how much energy the food contains.

Specific heat capacity is the amount of energy (Joules) needed to raise the temperature of 1kg of a substance by 1oC. The formula for specific heat capacity is:

Heat Captured (Joules)

=

Specific Heat Capacity of water(4.2 J/ oC)

X

Mass of water (g)

X

Change in temperature (oC)

Hypothesis

The peanut will release the most energy, because it has the most calories, followed by the potato chip and then the banana chip.

Peanut (28.3g)

166 Calories

Banana Chip (28.3g)

147 Calories

Potato Chip (28.3g)

155 Calories

Source: http://caloriecount.about.com/

Apparatus:

1 Copper beaker

1 electronic balance

1 Measuring cylinder

1 tripod stand

3 pins

1 Digital thermometer

1 Bunsen burner

1 pair of tongs

Peanut

Banana chips

Potato chips

Variables:

Controlled: Mass off water (50g)

Independent: Type of food (peanut, banana chips, potato chips)

Dependent: Change in temperature of water

Procedure

1. Measure the mass of your food using the electronic balance

2. Accurately measure 50 ml of water in a measuring cylinder and pour the water in the copper beaker

3. Put the beaker in a tripod stand

4. Measure the initial temperature of water using the digital thermometer and leave the thermometer inside the water throughout the experiment

5. Put a pin through your food and hold the pin using the tongs and burn the food using the Bunsen burner

6. Get your food under the copper beaker and leave it burning under the beaker till it completely burns out

7. Measure the final temperature of the water

8. Measure the final mass of your food.

9. Repeat the experiment again with different foods

10. Compare between the foods and draw conclusions as to which food contains the most energy per gram.

Food

Mass of water (g)

Initial Mass of food (g)

Final Mass of food (g)

Initial temperature (oC)

Final temperature (oC)

Peanut

50

0.95

0.18

26.7

47.9

Banana chip

50

2.57

0.45

26.7

46.8

Potato Chip

50

3.35

0.30

26.4

53

Results: Raw Data

Results: Processed Data

Food

Change in Mass of food (g)

Temperature Increase (oC)

Heat Captured (Joules)

Heat Captured per gram (J/g)

Peanut

0.77

21.2

4452

5781.8

Banana chip

2.12

20.1

4200

1991.0

Potato Chip

3.05

26.6

5586

1831.5

Observation:

When we were burning the food a lot of (hot) oil was dripping out of the burning food item. The most amount of oil came out from the potato chip.

The copper beaker became extremely hot after the experiment was done.

Conclusion

As we had predicted in our hypothesis, and as our results and graph shows the peanut had the most energy. The Heat captured (energy) per gram of peanut was 5781.8 Joules, which was much higher than the other two foods. But part of our hypothesis was wrong because the banana chip had more energy (1991.0 Joules) than the potato chip (1831.5 Joules). We had predicted the potato chip to have more energy than the banana chip because it had more calories than the banana chip, but further research showed that the banana chip had a high percentage of saturated fat, compared to potato chips which had fat, but unsaturated fat and a healthy percentage of carbohydrates. Fats release 9 calories of energy per gram and carbohydrates release 4 calories of energy per gram.

Saturated fats are saturated with hydrogen i.e. they are bonded to as many hydrogens as possible. In unsaturated fats, there may be one or more double bonds. Hence saturated and unsaturated fats differ in their energy content and melting point. Since an unsaturated fat contains fewer carbon-hydrogen bonds than a saturated fat with the same number of carbon atoms, unsaturated fats will yield slightly less energy; also it might need more energy to release the energy to break the double bond. So we feel that all the energy was not released (less energy was released) from the unsaturated fats from the potato chip, even after it was completely burnt.

Banana chips are also high in sugar and Sugar has 4 calories of energy in every gram and sugar releases its energy instantly so that must have helped release the banana chip release more energy (as less would be left unreleased) and potato chips do not have a very high amount of sugar.

Even though both the banana chip and the potato chip had similar amounts of energy captured (stored) in it we feel that these were the reasons why the banana chip had slightly more energy in it.

Evaluation

We feel that this was a fair test because:

I. We used a copper beaker and copper is a good conductor of heat, rather than a glass beaker which is a poor conductor of heat, so as much heat as possible gets transferred to the water.

II. We divided the heat captured by the amount of the food used up so we get the heat captured(released) per gram, so we can make a fair comparison amongst all the foods, otherwise the potato chips which had the highest mass would obviously release the most overall energy.

We could improve this experiment by:

I. Using a different and a more accurate calorimeter like a bomb calorimeter, where the food is literally blown up and all the heat energy is accounted for. In this experiment a lot of heat energy was lost to many different things. For example through radiation and convection lots of heat was lost to the environment. Even though copper is a good conductor a lot of heat was wasted in heating up the entire beaker, and some of it would have been conducted to the tripod stand. Some of the heat would also be conducted to the metal pins and to the tongs. It could also be possible that some of the heat energy was not released even after the food item was completely burnt.

II. We could increase the amount of water so more of the heat is conducted to the water from the beaker than being wasted by heating up the beaker.

III. We should keep the Bunsen burner as close to the beaker as possible (without it heating the beaker up), so that minimum amount of energy is lost when we are moving the burning food from the Bunsen burner to the beaker.

IV. We should repeat the experiment more times, at least three times so we can omit any anomalies and get an average of all the readings and then compare because there will be a lesser chance of getting a wrong conclusion. Also sometimes the food (especially the chip) only gets burnt from one side and the other side is left not burnt or by the time we get the burning food to the beaker the fire extinguishes. So to reduce the impact of these kind of mistakes on our final conclusion we should repeat the experiment.

V. We could do the experiment with chips of different companies, which would be quite interesting and we would come to know which chips contain the most energy.