ENERGY FROM FOOD LAB Look at a nutrition fact label. What information is given about a serving of food besides the ingredients and/or food groups? How do you think this number is measured? Food is a storage of energy. When we eat food, this energy is converted into chemical energy. All human activity requires “burning” food for energy. Not all types of food release the same quantity of energy in calories when they burn or are metabolized. Whether food is fat, protein, or carbohydrate makes a difference in calorie counting. (Can you guess which food has the highest energy content per g?) Food energy is often expressed in a unit called a Calorie. In this experiment you will determine the energy released (in kcal/g) as various foods burn. Procedure: Safety: There will be open flames in the lab. Make sure that your hair and loose clothing is pulled back, so they do not come in contact with the flames. Wear your goggles at all times. Make sure that all flames are extinguished before leaving the lab area. 1. Add 100.0 mL of cold water into an empty, clean metal soft drink can. The density of water is 1.0 g/mL (this means that 1mL of water has a mass of 1g) . Record the mass of water in the can. 2. Measure and record the initial temperature of the water. 3. Hang the soda can to a clamp. 4. Carefully place the food sample a spatula. Measure and record the mass of the sample and spatula combined. 5. Place the sample under the can. Adjust the height of the clamp so that the sample is about 2 cm from the bottom of the suspended can. 6. Remove the sample from underneath the can. Light the sample. Once it begins to burn, push the sample underneath the can. (This prevents the water from being heated by the lighter.) 7. Use a temperature probe to stir the water gently as the food burns. Record the highest temperature reached by the water. The temperature probe should not touch the bottom or sides of the can. Determine and record the change in temperature. 8. After the sample has finished burning, measure and record the final mass of the sample and holder. Determine and record the mass of food burned during the experiment. 9. Empty the water from the can. Wash and dry the outside. Repeat steps 1-8 for the next sample. Conduct three trials of the food item you are testing. 10. Examine the package of the food you are testing. Record the serving size (grams/serving) and Calories per serving. Foods Available for Testing: Peanuts Saltine cracker Banana chips Potato chips Data Table Initial Final Mass Initial Final of temperature temperature mass Calories mass of food Serving of the water of the water of food per food + burnt size + serving spatula (In °C) (In °C) spatula Trial Peanuts 1 Trial 2 Trial 3 Saltine Trial cracker 1 Trial 2 Trial 3 Banana Trial chip 1 Trial 2 Trial 3 Potato Trial chip 1 Trial 2 Trial 3 Calculations: Assume that all of the energy released by the burning food goes into heating the water. One calorie is required to heat up 1g of water of 1 degree Celsius. How many calories were released by the burning of the peanut trial 1? Explain your calculation. Convert your answer to kCal. Record your answers for each trial in the table below. Calculate the energy content (in kcal/g) of each trial for your food sample burned in the experiment. Explain your calculation for the burning of the peanut trial 1. Record your answers for each trial in the table below. Determine the average energy content of the food samples you tested. Record in the table below. Energy released Energy content Average energy during burning (in (in kcal/g) content (kcal/g) kcal) Peanuts trial 1 trial 2 trial 3 Saltine trial 1 cracker trial 2 trial 3 Banana trial 1 chip trial 2 trial 3 Potato trial 1 chip trial 2 trial 3 Data Analysis: 1. a. For the food you tested, calculate the number of food Calories that are in one serving of food. Use your experimental average energy content and the serving size from the package. b. Compare your Calorie value with the accepted value of Calories/serving from the package. Calculate your percent error. c. Identify two possible experimental errors. 2. a. Very light activity, like reading, uses about 7 kJ/min. How many minutes of reading could you do by the energy provided by one serving of the food you tested? b. A person of average weight uses about 100 Cal/mile when jogging. How many servings of this food provide the energy value requirements for running 3 miles? Conclusion: What did you learn from doing this experiment?
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