Measuring Calories...Calorimetry Lab
Energy Content of Food
Introduction
All human activity requires “burning” food for energy. How much energy is
released when food burns in the body? How is the caloric content of food determined?
Lets investigate the caloric content of different snack foods such as marshmallows and
cheese puffs.
Hypothesis – Write on your lab sheet!
Concepts
* Combustion reaction * Calorimetry
* Nutritional calorie * Caloric content of foods
Background
What does it mean to say that we burn food in our bodies? The digestion and
metabolism of food converts the chemical constituents of food to carbon dioxide and
water. This is the same overall reaction that occurs when organic molecules—such as
carbohydrates, proteins, and fats—are burned in the presence of oxygen. The reaction of
an organic compound with oxygen to produce carbon dioxide, water and heat is called a
combustion reaction. The chemical equation for the most important reaction in our
metabolism, the combustion of glucose, is shown in Equation 1.
C6H12O6 + 6O2 6CO2 + 6H2O + heat Equation 1
With in our bodies, the energy released by the combustion of food molecules is
converted to heat energy (to maintain our constant body temperature), mechanical energy
(to move our muscles), and electrical energy (for nerve transmission). The total amount
of energy released by the digestion and metabolism of a particular food is referred to as
its caloric content and is expressed in units of nutritional Calories (note the uppercase C).
The caloric content of most prepared foods is listed on their nutritional information
labels.
Nutritionists and food scientists measure the caloric content of food by burning
the food in a special device called a calorimeter. Calorimetry is the measurement of the
amount of heat energy produced in a reaction. Calorimetry experiments are carried out by
measuring the temperature change in water that is in contact with or surrounds the
reactants products. (The reactants products together are referred to as the system, the
water as the surroundings.)
Purpose
The purpose of this experiment is to determine the amount of heat released when Cheetos
are burned versus marshmallows.
Materials:
Balance Matches
Calorimeter(Soda Can) Cheetos/Marshmallows
Cork and pin Thermometer
Graduated cylinder, 50-mL Water
