Purpose
To measure the caloric energy content of food.
Concept
The energy people need comes from the food we eat. A calorimeter is a device
used to measure changes in thermal energy. In this experiment, the energy lost
by a sample of food will be equal to the energy gained by a sample of water,
and the total energy of the system (food plus can of water) will stay the same.
Materials
Ring-stand, beverage can, thermometer, graduated cylinder, 100 ml water,
peanut, potato chip, long pin, tongues, matches, balance.
Procedure Part A
1. Measure and record the mass of a peanut.
2. Measure and record the mass of a potato chip.
3. Set up the calorimeter and pour 100 ml of water tap water inside.
4. Record the initial temperature.
5. Place a dry-roasted peanut on a pin and hold under the pop can. Carefully light with a match and hold the peanut under the pop can until it stops burning.
6. Record the final temperature of the water.
Part B
1. Repeat the experiment holding a potato chip with tongues.
Analysis
1. Calculate the change in temperature of the water for part A and part B.
2. Calculate the energy gained by the water for part A and B.
3. Assuming the energy gained by the water is equal to the energy lost by the food sample, divide the energy lost by the food sample by the mass of the food sample for part A and B.
4. Which food sample has more energy per unit mass, a peanut or a potato chip?
5. Describe possible sources of error in this experiment. Did all of the energy go into the water? Explain.
