Class: BE-210
Group: W6
Members: Jason Christos, Latressa Fulton, Vinod Mapranath, Melinda Patterson
Date: 4/30/97
Full Text

Abstract:
It is useful to measure the heat of combustion of alanine because it represents the maximum energy an organism can obtain from a metabolite. With the availability of an advanced instrument called a Bomb Calorimeter, it is possible to accurately measure the heat combustion of a material with the appropriate standardized energy equivalent.

A crucial part of this lab is the accuracy of the given energy equivalent, W. W describes the change in heat of the system due to a change in temperature of the water. The bomb calorimeter is fired by causing a current to flow through a circuit. The fuse wire heats up the benzoic acid for the calibration and the alanine for determination of its Hc until the fuse burns off and breaks the circuit. This causes the combustion of the material, but also causes other heat including the combustion of the fuse wire and side reactions such as nitric acid. The heat of combustion of the fuse wire is determined by measuring the length of the fuse wire burned and multiplying it by a constant. The amount of nitric acid formed is found by titrating it with 0.0709N alkali. The heat of combustion of alanine is accurately calculated from the heat transferred to the entire system and subtracting any heat contributions from the burning of the fuse wire and side reactions. After considering all these correction factors and the net corrected temperature change of the water, the value obtained for the energy equivalent is 2429.9 + 51.3 cal/degC and alanine’s heat of combustion is 4284.8 + 113.1 cal/g. The energy equivalent deviates from the accepted value by 0.16% and the heat of combustion deviates from the accepted value by 0.14%. These values show that the data is extremely accurate.