Find out which type of food from a particular type of group has the most energy per gram.

Fat: - 1g give 34Kj

Carbohydrates: - 1g give 17Kj

Proteins: - 1g give 17Kj

Even though fat produces twice as much energy as carbohydrates and proteins it is not good for the diet. Modern foods contain more fat than the body requires. Sweets give a person a lot of energy because it’s amount of fat is high and is not good for the body. People these days now watch what they eat and try to eat foods that contain less fat and more carbohydrates and protein, they eat foods like pasta, crisp bread etc. the table above also show these foods contain very little fat.

We can calculate the amount of energy from different types of food by burning it. Food is a fuel, when it is being burned its energy is being transferred to its setting, the main type of energy transferred is heat. This lets us find out how much energy is given off from the different types of food.

Variables: -

Independent variable: -

The independent variable is the type of food, it is this because I will be changing the different types of food.

Dependant variable: -

The dependant variable is the energy per gram, this is the dependant because the energy differs for each food.

Control variable: -

The control variable is the type of test tube. Different test tubes use different thermal conditions so to make it a fair test you have to use the same test tube each time.

Another control variable is the distance at which the food is held from the test tube. If they are held at different positions each time it doesn’t make the test fair.

Preliminary Results: -

   

These are the results from my preliminary experiment, I only used crisp bread and pumpkin seeds as my independent variables. My main experiment will have more independent variables. For this experiment we only used two different independent variables. We had to burn both types of food twice to get our results I did extra so I could get more accurate results.

Prediction: - 

Using my scientific knowledge and my preliminary results I predict that the food containing most fat will have the most energy, because 1g of carbohydrate or protein releases 17Kj but 1g of fat releases 34Kj that is twice as much. I predict that the independent variable that will have the most energy will be the sunflower seed I am using the table in my scientific knowledge and preliminary graph to back up my prediction.

Apparatus: -

• Boiling tube
• Bunsen burner
• Safety mat
• Stand, boss and clamp
• Goggles
• Measuring cylinder
• Thermometer
• Probe
• Electronic balance
• Water
• Independent variables (types of food)
• syringes

Diagram: - 

Safety Features: -

• Goggles must be worn at all times, this is because there are Bunsen burners on around the whole room, don’t want any injuries from open flames.
• The boiling tube must properly clamped to avoid it slipping when you are burning it.
• The Bunsen burner should be on safety flame at all times, to avoid injury from burning.
• The Bunsen burner must be away from the edge of the table and the clamp so it doesn’t get knocked over and cause injury.
• Any one with long hair should tie his or her hair up or anyone wearing a tie should tuck it in so no one’s hair or tie catches fire.
• There must be a safety mat underneath the burning food, so no ones hand gets burnt.
• Keep the Bunsen burner near the test tube so you are not carrying around burning food.  

Method: -

1. Measure out 20cm³ of water then put it into a boiling test tube.
2. Clamp the boiling tube properly to the stand and put a thermometer inside the tube.
3. Record the temperature of the water before you start the experiment.
4. Weigh your independent variable on the electronic scale, make sure you record down the weight.
5. pierce your piece of food with a probe, then place it in the flame of the Bunsen burner until it is alight then take it out and hold it underneath the boiling test tube until it burns out.
6. when the food stops burning record the temperature of the water again.  

Plan: -

I’m going to want to make it a fair test so I get accurate results. I will do this by making sure that there 20cm³ of water in the test tube every time I burn I different type of food. The distance at which the burning food is held from the test tube, it has very hard to get the burning food in the same position every time but you have to be accurate as possible, so it is a fair test. Also you have to use the same test tube for every time you burn a different food because different test tubes have different thermal conditions so using the same one makes it a fair test.

When you start the experiment before you burn anything take down the start temperature of the water, then when you have finished the experiment take down the end temperature and then record the temperature difference, do this for every independent variable you burn.

Try and do the experiment twice so you get more accurate results and also you can then work out an average.  

Conclusion: -

I conclude that the more fat there is in the food the more energy is released. My prediction was correct, the sunflower seed had the most energy out of any of the other independent variables. The sunflower seed had the most energy because it has the most fat in it.

There is an abstract pattern in my graph, one of the sunflower seeds has a lot of energy it has up to 6462k/j in 1g. The other sunflower seed has only 2800k/j in 1g. With all the other independent variables pastas, dried peas and crisp had very little difference in energy between each other. I think the sunflower seeds had a very big difference mainly because the seeds selected just had different amounts of fat in them.

Evaluation: - 

The method I used I think gave pretty accurate results, but I think my results could have been more accurate in the way I performed the experiment. To get more accurate results I should have held every single piece of food the same distance away from the test tube. But the method I used gave reliable enough results even though they could have been more reliable. The whole experiment is based on finding the amount of energy given off by using heat, but the results couldn’t have been very reliable because heat was let out to the surrounding area. Also the temperature could have gone up because there were another 14 Bunsen burners on in the room. So to have made this experiment totally accurate, it should be done inside some kind of air tight place so no heat is lost, and only one experiment at a time should be done so there isn’t extra heat being given. The energy difference between the sunflower seeds in the main experiment was large. I think this was because I had just picked up two sunflower seeds with a big difference in fat. The one that had 6462k/j in 1g obviously had more fat in it.