Prelab 428R

# Prelab 428R - energy is smaller, because it takes into...

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KEY to PRELAB 428: Estimating the Calorie Content of Nuts 1. You can burn your fingers, singe your hair, or ignite paper if matches/splints are not used properly. 2. a. An exothermic reaction is a reaction that produces energy b. A combustion reaction is a reaction of a compound with oxygen (O 2 ) that forms carbon dioxide and water. c. A fatty acid is an organic compound that contains a carboxylic acid and has 10 or more carbon atoms. d. The specific heat capacity of water describes the relationship between the temperature change of water to the energy input or loss. e. The physiologic energy values for lipids represent the actual energy content of each lipid that is available for use by the human body. Not all of the energy in foods can be extracted and used by the human body. 3. a. We will be determining the gross energy of the peanut in this experiment. The physiologic
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Unformatted text preview: energy is smaller, because it takes into account slight inefficiencies in metabolic processes and energy losses within the body. b. We will base the calculation of percent difference on the accepted Caloric content of the peanuts, as listed on the container label. 4. a. Mass peanut burned = mass peanut mass residue 0.609 g 0.053 g = 0.556 g b. density of water = 1.00 g/mL, thus 200 mL = 200 g, which equals 0.200 kg. c. energy released = mass of water in cup x specific heat x temp. change q = m c T q = (0.200 kg)(1 Cal/kg C)(14.2 C) q = 2.84 Cal Note: the size of a degree in the Celsius and Kelvin scales is the same. Since we are computing temperature change, it is not necessary to convert from C to K or vice versa. d. Cal/g = q/mass burned 2.84 Cal/0.556 g = 5.11 Cal/g...
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## This note was uploaded on 02/21/2011 for the course CHEM 1280 taught by Professor Schmidt during the Fall '07 term at Toledo.

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