| The Heat Is On |  |
Introduction:
Energy comes in a variety of forms: light, heat, motion, electricity, and so forth. The energy in food is measured in units of Calories. A Calorie is defined as the quantity of heat it takes to raise the temperature of 1 kg of water 1 degree Celsius. The energy in food is defined in terms of heat because the quantity measured is heat produced upon burning the food. Burning in the presence of oxygen is the process of combustion. Complete combustion results in the production of energy as well as carbon dioxide and water.
Plants utilize sunlight throughout photosynthesis to convert carbon dioxide and water into glucose and oxygen. This certain glucose has energy stored in its chemical bonds that can also be used by other organisms. This stored energy can be released whenever these chemical bonds are broken in metabolic processes for instance cellular respiration. When this experiment partakes you will have to measure the amount of energy that is available for use from types of nuts, preferably pecan because they have the most oil to burn. The process you are doing is known as calorimetry.
Hypothesis:
If calories are measured by the heat given off from the burning nut changing the temperature in the given amount of water, then the energy stored in the nut can be measured.
Materials:
The materials needed to construct this experiment are a large paper clip, thermometer, soft drink can, soft drink can with openings cut into the side, one whole pecan, matches, water, pencil and paper, scissors, plastic tray, graduated cylinder, calculator, and a electronic balance.
Methods:
First, carefully cut out two openings along the side of a soft drink can. This will serve as your support for the second drink can that will contain water and sit on top. Then bend a large size paper clip so that a nut can be attached on one end and the other end will sit flat inside the cut out soft drink can. Next, use the graduated cylinder to accurately measure 100g of water. Pour this water into the uncut soft drink can. Then use the thermometer to measure the temperature©. Record this temperature on the data table. Mass the nut (g) that you will burn and record this mass on your data table. Next, attach the nut to the bent end of your paper clip and carefully set the clip and nut into the cut-out soft drink can on bottom. Make sure the cans are sitting on a flat, nonflammable surface! Carefully light the nut using a match and record the change in water temperature as the nut burns. Record the final water temperature as the nut burned. Then measure the mass (g) of the remaining nut and record this in the data table. Complete the data table by calculating the change in mass of the nut and the temperature of the water. If you have enough time repeat this experiment with a different type of nut but remember to always start with cold water and to take the initial and final water temperature and mass of the nut.
Results:
Data Table 1
Nut used pecan | Before Burning | After Burning | Difference |
| Mass of nut (g) | 1.4 g | .1 g | 1.3 g |
| Temperature of water © | 22 © | 41 © | 19 © |
Data Table 2
| Mass of the burned pecan | 1.3 g |
| Temperature change of 100mL of water | 19 degrees C |
| Calories required to produce temperature change in 100mL of water | 1900 calories |
| Calories per gram contained in the pecan | 1357.1 |
Questions:
- What is the relationship between matter and energy? The more the matter the more the energy.
- What do we call stored energy and where is energy stored in compounds such as glucose? We call it glycogen, and its stored in the bonds.
- Discuss what happened to the energy stored in the nut? It was released by the heat.
- Why was the mass of the less after burning? The oils in the nut were evaporated.
- How do our bodies make use of this process? They break down the glucose to form energy known as glycogen.
Error Analysis:
Errors could have occurred if all the oils were not all evaporated during the process of burning of the pecan. Also if you didn’t use the correct amount of water this could have caused an inaccurate measurement.
Discussion and Conclusion:
The temperature of the can with 100mL of water in it changed from the energy stored in the pecan. The temperature of the water started out being 22 degrees C and as the pecan burned it released the energy and heated the water to 41 ©. Also the mass of the pecan before it was burned was 1.4g and after burning was .1g. One calorie equals the heat required to change the temperature of 1 gram of water 1degree C. In this experiment, the temperature change was 19degrees C which meant 1900 calories were produced to change the temperature of the water. With the mass of the nut before burning and the amount of calories required to change the temperature gave me the information to find that my pecan had 1357.1 calories in it.
