Lab 18 - Burning Food

Lab 18 “Burning Food. Where are my carbs?” Introduction: Our bodies digest and metabolize food that we eat, through chemical reactions, and they release energy to fuel our bodies. This is done using oxygen for a combustion reaction. We used calculations that were obtained by using bomb calorimetry, which allowed us to determine the heat released through the process of burning food, and this is done by using volume-constant calculations. We initially determined the calorimeter constant using glucose, and then we saw how much energy was released when food burned in our bodies, and we found the caloric contents of various snacks that we consume. Materials: 1) Lab manual- Used to learn lab procedures, and guidelines. 2) Excel- Used to create charts for the data. 3) Calculator- Helped us with calculations. Observations and Experimental: Part 1: Determination of the calorimeter constant 1) C 6 H 12 O6 +6O 2 →6 C O2+6 H 2 O 2) Δ H rxn :(6∗− 242)+( 6∗− 393.5)−(−1275 )=−2358 kJ /mol 3g =0.017 mol glucose | 2358 kJ /mol∗¿0.017mol glucose = 42.3 kJ 1224 g 42.3 kJ = C cal∗4.3° C∨C cal =9.83 kJ /°C Part 2: Energy content of various snacks q calorimeter = ΔT∗C qcalorimeter (30.92−26.12 )∗( 9.8372) = =19. 5927634855 kJ / g mass 2.41 g 19.5928 kJ ∗28 g 1g ∗1 cal 132.56 cal/oz 1 oz =¿ 4.184 KJ Percent error: Label − Actual 133.31−132.56 = =0.56 % error Label 133.31 This chart compares the energy content on the label of the snacks, with the actual energy content. 4. A. Beef jerky (Lowest energy content) B. Microwave content C. Oreo cookies D. Crunchy Cheetos E. Oil-roasted, salted peanuts (Highest energy content) 5. The oil-roasted, salted peanuts have a higher energy content than beef jerky in terms of calories per ounce because the beef jerky is composed of mostly protein, whereas peanuts have a high-fat content, and they are oil roasted, which adds more fat. Discussion and Conclusion: In this lab, we gained an understanding of how we metabolize food and convert what we eat into energy that we use in our daily lives. We initially determined the calorimeter constant using glucose, and then we saw how much energy was released when food burned in our bodies, and we found the caloric contents of various snacks that we consume. We were also able to see the vast disparity in the number of calories that proteins and fats provide, even with the same mass consumed. This lab was helpful in allowing us to see how certain foods can provide much more energy, and should be consumed in moderation. Focus Questions: 1) How much energy is released when food burns in the body? The amount of energy released when food burns in the body depend on the food that is eaten and the energy content ( in calories) that the food contains. 2) How is the caloric content of food determined? Caloric content of food is often listed on labels, but it can be determined by individuals by using a bomb calorimeter. The food is often put into a sealed box that is filled with water and then the temperature is increased until the food burns. Post Lab Questions: 1) Oil roasted, salted peanuts had the highest calories per gram. I am not surprised by this because the oil-roasted, salted peanuts are high in fat, and are roasted in oil. 2) The foods that store the most energy are the oil-roasted, salted peanuts, due to their high-fat content. 3) It is important to calculate calories per gram rather than calories burned because we get a more precise amount of energy that we consume. 4) Heat of combustion of sucrose: 3.150 g = 0.0092 mol 342.2965(g/ mol) (27.64−23.42)× 4.90= -20.678 kJ −20.678(kJ ) =¿ -2247.61 kJ/mol .0092(mol)