Stored. Introduction: Name. process by. of usable. respiration. stored energy. allowing us to. the. that can be will indirectly.

Transcription

1 The Heat is On The Enery Stored in Food Introduction: Plants utilize sunliht durin photosynthesis too convert carbon dioxide and water into lucose (suar) and oxyen. This lucose has enery stored in its chemical bonds that can be used by other oranisms. This stored enery is released whenever these chemical bonds are broken in metabolic processes such as cellular respiration. Cellular respiration is the process by which the chemical enery of "food" molecules is released and partially captured in the form of ATP. Cellular respiration is the eneral term which describes all metabolic reactions involved in the formation of usable enery from the breakdown of nutrients. In livin oranisms, the "universal" source of enery is adenosine triphosphate (ATP). Carbohydrates, fats, and proteins can all be used as fuels in cellular respiration, but lucosee is most commonly used as an example to examine the reactions and pathways involved. Marathon runners eat a lare plate of pasta the niht before a competition because pasta is a ood source of enery, or fuel for the body. All foods contain enery, but the amount of potential enery stored will vary reatly dependin on the type of food. Moreover, not all of the stored enery is available to do work. When we eat food, our bodies convert the stored enery, known as Calories, to chemical enery, thereby allowin us to do work. A calorie is the amount of heat (enery) required to raise the temperature of 1 ram () of water 1 deree Celsius ( C). The density of water is 1 ram per milliliter (1/ml) therefore 1 of water is equal to 1 ml of water. When we talk about caloric values of food, we refer to them as Calories (notice the capital C ), which are actually kilocalories. There are 1000 calories in a kilocalorie. So in reality, a food item that is listed as havin 38 Calories hass 38,000 calories. Calories are a way to measure the enery you et from the food you eat. Just as pasta can provide a runner enery to runn a marathon, a tiny peanut contains stored enery that can be used to heat a container of water. For this lab exercise, you will indirectly measure the amount of Calories in couple of food items usin a calorimeter. A calorimeter (calor = Latin for heat) is a device that measures the heat enerated by a chemical reaction, chane of state, or formation of a solution. There are several types of calorimeters but the main emphasis of all calorimeters is to insulate the reaction to prevent heat loss. We will be usin a homemade calorimeter modeled after a constant volume calorimeter. A particular food item will be inited, the homemade calorimeter will trap the heat off the burnin food, and the water above will absorb the heat, thereby causin the temperature (T) of the water to increase. By measurin the chane in temperature ( T) of a known volume of water, you will be able to calculate the amount of enery in the food tested Pae 1 of 5

2 Objective: In this experiment, you will measuree the amount of enery available for use from three types of nuts, a plant product. This process of measurin the enery stored in food is knownn as calorimetry. Materials: lare paper clip, o C thermometer, soft drink can, soft drink can with openins cut into the side, mixed nuts, matches, water, electronicc balance, pencil & paper, 100 ml raduated cylinder, calculator Procedure: 1. Carefully, cut out two openins alon thee side of a soft drink can. This will serve as your support for the second drink can that will containn water & sit on top. 2. Bend a lare size paper clip so that a nutt can be attached on one end and the other end will sit flat inside the cut out soft drink can. 3. Use the raduatedd cylinder to accuratelyy measure 100 (100ml) of water. Pour this water into the uncut soft drink can. 4. Place the thermometer in the uncut can and measure the water temperature Pae 2 of 5

3 after 3 minutes. Record this temperature e on data table Mass the nut () that you willl burn and record this mass on dataa table Attach the nut to the bent end of your paper clip and carefully set the clip & nut into the cut out soft drink can on bottom. Make sure the cans are sittin on a flat, nonflammable surface! 7. Carefully liht the nut from the bottom usin a match and record the chane in water temperature as the nut burns (thermometer in the can durin burnin). Immediately after the nut finishes burnin, record the final (hihest) water temperature on data table Measure the masss () of the remainin nut & record this in the data table 1. (Mass the burned nut and paper clip toether and then subtract the mass of the nut to et the mass of the nut alone.) Pae 3 of 5

4 9. Complete the data table1 by calculatin the chane in mass of the nut. 10. Repeat this experiment with the other two types of nuts. 11. When all three nuts have been burned, complete the analysis on data table 2. Results: Table 1 Results of Burnin PECAN WALNUT ALMOND H 2 O temperature Before burnin H 2 O temperature After burnin Difference in o C H 2 O temperature Mass of Paper Clip Mass of Nut Before Burnin Mass of Paper Clip and Nut After Burnin Mass of Nut ALONE After Burnin (Subtract paper clip mass from mass of nut & paper clip after burnin) (Subtract paper clip mass from mass of nut & paper clip after burnin) Table 2 Data Analysis from Nut Calorimetry PECAN WALNUT ALMOND Mass Difference of Nut Before & After Burnin (Subtract mass of nut after burnin from Mass of nut before burnin) Temperature Difference of H 2 O Before & After Burnin (Subtract oriinal water temp. from final water temp.) Calories Required to Chane the Temperature of 100 of H 2 O (Multiply temperature chane by 100) Cal Pae 4 of 5

5 Averae Calories per ram in the Nut (Divide the total calories by the mass difference of the nut before & after burnin) Cal/ Averae kilocalories or food calories per ram (Divide the calories per ram by 1000) kcal/ Questions & Conclusion: 1. Where did the enery stored in the nut oriinally come from? 2. Durin what process was this enery stored in the nut, & where specifically was it stored? 3. What simple suar made by plants is a common source for stored enery? 4. Which roup of macromolecules would a nut contain carbohydrates, lipids, or protein? 5. What is the name for stored enery? 6. Give some examples of how oranisms would use this stored enery. 7. In this experiment, discuss what happened to the enery stored in the nut. 8. Why was the final mass of the nut less than the oriinal mass of the nut? (Remember that matter can't be destroyed in a chemical reaction.) Pae 5 of 5