Energy Content in Food Lab - Bloomer High School

Energy Content in Food Lab Problem: How much energy do different types of food contain? Can we get our results to compare well to the published amount of Calories? Equipment:         

Computer and LabPro Temperature Probe Ring stand with ring Utility clamp Small can w/ stirring rod 100 mL graduated cylinder Matches and wooden splint Two food samples Paperclip food holder

Hazard Warnings and Procedure Notes:  ABSOLUTLY NO EATING  Goggles must be warn throughout this lab  Match and wooden splints need to be totally cooled with water before being thrown away Procedure: 1. Obtain and wear goggles. 2. Obtain a piece food and a food holder like the one shown in Figure 1. Find and record the initial mass of the food sample and food holder. CAUTION: Do not eat or drink in the laboratory. 3. Determine and record the mass of an empty can. Add 50 mL of cold tap water to the can. Determine and record the mass of the can and water. 4. Set up the apparatus as shown in Figure 1. Use a ring and stirring rod to suspend the can about 2.5 cm (1 inch) above the food sample. Use a utility clamp to suspend the Temperature Probe in the water. The probe should not touch the bottom of the can. 5. Connect the probe to the LabPro. 6. Open LoggerPro. Go to File>Open>Chemistry with Vernier folder>”16 Energy of Foods” file. 7. Click to begin measuring temperature. Record the initial temperature. Remove the food sample from under the can and use a wooden splint to light it. Quickly place the burning food sample directly under the center of the can. 8. Gently stir the water so the Thermal Energy distributes throughout the can. Allow the water to be heated until the food sample stops burning. CAUTION: Keep hair and clothing away from open flames. 9. Continue stirring the water until the temperature stops rising. Record this final temperature. Click to end data collection. 10. Determine and record the final mass of the food sample and food holder. 11. To determine the initial temperature, t1 and final temperature, t2, click the Statistics button, . The minimum and maximum temperatures are listed in the statistics box on the graph. 12. Repeat the procedure for the second food sample. Use a new portion of cold water.

Data: Energy Content in Food:

Food type Mass of empty can

–––––––––––––––––– g

–––––––––––––––––– g

Mass of can and water Initial mass of food and holder

g

g

g

g

Final mass of food and holder Mass of food burned

g

g

g

g

Initial temperature, to

°C

°C

Final temperature, tf

°C

°C

Temperature change, ∆t

°C

°C

Analysis of Data/Conclusion Questions: Energy Content in Food: 1. Using the mass of water and change in temperature determine the energy absorbed by the water due to heating (Q) for each food type, Report the answer in kJ. (mC∆T) 2. Using you results from #1 and the mass of food burned, calculate the energy content (in kJ/g) for each food sample. 3. Food energy is measured in Calories. There are 4.18 kJ in 1 Cal. Calculate the number of Calories per gram of your food. 4. The following amounts are one serving size: a. Peanuts, 28 g b. Cashews, 28 g c. Marshmallows, 30 g d. Popcorn, 33 g Based on your data calculate the number of Calories per serving in each food you tested. 5. According to the manufacture’s label each food contains the following number of calories per serving: a. Peanuts, 160 Cal b. Cashews, 170 Cal c. Marshmallows, 100 Cal d. Popcorn, 110 Cal How does your calculation from #4 compare to the numbers given above? List at least two reasons why those numbers are different. 6. Peanuts and cashews have a high fat content, marshmallows and popcorn are high in carbohydrates. From your results, what generalization can you make about the relative energy content of fats and carbohydrates.