energy of a peanut

# energy of a peanut - ENERGY OF A PEANUT AN EXPERIMENT IN...

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ENERGY OF A PEANUT AN EXPERIMENT IN CALORIMETRY ©2011, 2010, 2002, 1995, by David A. Katz. All rights reserved. Reproduction permitted for educational use provided original copyright is included. INTRODUCTION: Calorimetry is a technique that is used to determine the heat involved in a chemical reaction. When determining the heat of combustion of a substance or the caloric value of foods, the measurements are often made using a bomb calorimeter . In this device, the weighed sample is placed in a heavy steel container called a bomb and the atmosphere of the bomb is filled with pure oxygen. The bomb is then placed in a well insulated container called a calorimeter which has been filled with a measured amount of water. The sample, in the pure oxygen atmosphere, is ignited by an electric spark and the heat generated by the burning sample warms the bomb and the surrounding water. At equilibrium, both the bomb and the water will be at the same temperature. Using the law of conservation of energy: Heat evolved by the reaction = Heat absorbed by the water + Heat absorbed by the bomb or, in equation form: q reaction = -(q water + q bomb ) (where q is the symbol for heat) The q reaction has a negative value because the combustion reaction is exothermic (i.e., it releases energy to the surroundings). The q water and the q bomb are calculated from the temperature change of the water and the bomb and the specific heat of the water and the bomb. The total gives the heat of combustion of the sample that was used. In this experiment, the energy of a peanut, or another kind of nut, will be determined using a simplified set-up. The peanut will be burned in air, instead of pure oxygen. Instead of a heavy metal bomb, a metal can, such as an aluminum soft drink can. small juice or soup can is used. To eliminate the determination of the specific heat of the metal can (the heated needed to heat the metal that composes the can), the experimental conditions are modified to maintain a constant temperature of the can by filling it with a large quantity of ice. This will maintain a temperature of 0ºC, as long as all the ice does not melt. The heat evolved by the burning peanut will melt some of the ice and the amount of liquid water formed will be measured to give the heat of combustion of the sample. After determining the energy of a peanut, (or other type of nut) the procedure will be repeated using other snack foods.

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energy of a peanut - ENERGY OF A PEANUT AN EXPERIMENT IN...

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