Class: BE-210
Group: R3
Members: Luis Otoya, Jeannette Ouyang, Nick Rose, Jennifer Russert, Edwin Tan
Date: Spring 1997
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Abstract:
Our main objective of this lab was to determine the heat of combustion for an amino acid that plays a significant role in the biological system. Both Leucine and Valine were combusted in a standardized bomb calorimeter with energy equivalent, W, equal to 2424.69 + 12.73 cal/g. Leucine and valine were chosen because they have similar structures with the exception of a CH2 group. Standardization was done by combusting pure benzoic acid in the calorimeter. After, combustion data was taken in 30 second intervals and then analyzed along with the remaining components of the post-combustion bomb giving a heat of combustion value. This was done utilizing certain equations that include an account of possible errors within the bomb calorimetry technique (explained in the background). The average heat of combustion values of Leucine and Valine were calculated to be 6510.24 + 34.91 cal/g and 5909.34 + 55.86 cal/g yielding only .081% error for Leucine and .440% error for Valine. Through experimental trials, we determined that the heat of combustion of Leucine is greater than that of Valine. The fact that the heat of combustion is greater than Valine is consistent with the fact that Leucine has one extra CH2 group than Valine, thus more energy is released when the extra bonds are broken. Though the amino acids were seen to release nearly twice the amount of energy of sucrose (3897.30 + 33.31 cal) did when they were combusted, it was concluded that sucrose was still a more efficient source of energy within the body.