ࡱ> 574 bjbj ."՟՟ &&&&&::::N$:7rrrrrMMM$"\&MMMMM&&rrM"&r&rMDvg_o.F07^"B"0v&v,MMMMMM7MMMM"MMMMMMMMM* :   IB Biology Name_______________________________ Measuring the Energy Stored in Nuts Period__________ Date______________ Background Information: The molecules in food such as raw nuts have energy stored in the bonds that hold the atoms together. This potential energy can be released as heat when the nut is burned. Burning, also called combustion, is a reaction that involves oxygen reacting with the nut so that the carbon dioxide, water, smoke (Carbon atoms) and heat are given off. Nut + O2 ( CO2 +H2O + C + (H In this experiment you are to observe what happens and verify as many of the facts as you can. You will also measure the amount of heat released. Use calories as your unit of heat. Recall that 1 calorie is the amount of heat needed to raise that temperature of 1g of water 1 (C. Also recall that 1 ml of water has a mass of 1 g. Questions: Which kind of raw nut contains the most energy per gram? How accurate was the data collected? Hypothesis: If a burning piece of nut is used to heat water, then the temperature change in the water per ml of water equals the number of calories released from the nut as it is burned. 2. If different kinds of nuts are burned, the kind that raises the ____________________________________ Procedure: 1. Set up the apparatus as diagrammed and demonstrated. Measure 15ml of water into a test tube. Record this number as a mass of water. Measure the mass of the piece of nut. Record its mass. Measure the temperature of the water. Record it. Why use Celsius scale?__________________________________ Burn the piece of nut completely to ash or until water temperature has raised at least 10(C (More is better). Catch the heat so that it heats the water as it burns. Monitor the temperature of the water. Read the highest temperature achieved. Record it. Measure the final mass of the piece of nut and find its change in mass and record it. Starting with fresh water, repeat steps 2-6 with each kind of nut. Determine the change in temperature ((T). Record it. Calculate the number of calories released by each piece of nut. Record this number. Calculate how many calories per gram this represents. Record the answers. Enter your groups data into the class data chart in class or flex. Calculate the mean calories per gram for each type of nut. Also propagate uncertainty for the average. Record it. Results: Use the data tables provided to you for recording data and calculated answers. Be sure to include descriptive titles on both. Annotate the first data chart describing how you got the uncertainty for the three tools you used. Show four sample calculations using the 4-step method on a separate piece of paper (change in temperature OR change in mass of the nut, energy, energy per unit mass, and average energy per unit mass). Be sure to carry units throughout! Include the propagation of uncertainty. Conclusion: In a paragraph write conclusions that include, but are not limited to, the answers to the stated questions at the beginning of the lab. Discuss the data in full. Evaluation: Include one specific strength of your procedure. In a data chart describe at least three weaknesses or sources of experimental error in this procedure, how they impacted your data, and suggest ways to make the procedure or apparatus better. 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