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Online Chemistry Labs | Learning Objectives

Background:

This laboratory introduces students to calorimetric determination of the heat of combustion of a food substance. After performing a calibration run with a measured amount of Al powder with known heat content, the student calculates the calorimetric response of the equipment. The student next combusts a measured mass of an unknown food and measures the heat rise. The student is assigned two of several different unknown food compounds. From the observed joules/g released, the student is asked to compare the measured heat contents with those in a list of comparable foods. A realistic set of time-temperature data curves require extrapolation to obtain the true temperature change.

Food Energy

Learning Objectives:

  1. Become familiar with the principles of an oxygen calorimeter for burning a substance by manipulating the equipment.
  2. Introduce the concepts of calibration and extrapolation of time-temperature data to deal with heat losses and non-linear drift.
  3. Perform the calculation of the equipment response factor.
  4. Illustrate how to determine the heat of combustion of an unknown.