Energy Content of Foods
Your Name
Lab Partners:
Period:
January 28, 2013
Background Information:
Heat is energy that transfers from one object to another because of a temperature difference
between the objects. Heat is measured in a calorimeter and the units for heat are joules or
calories. The calorimeter uses the Law of Conservation of Energy which states that energy is
never created or destroyed but is transferred between objects.
Temperature is a measure of the average kinetic energy of the particles an object which is
different that the heat which is all the energy in the object. Temperature can be used to
calculate heat by looking at the change in temperature.
Energy can be calculated using the formula: Q = mc ∆T. In the formula, Q = the energy in
joules or calories, m = the mass in grams, c = specific heat and ∆T = the change in
temperature which is the final temperature minus the initial temperature.
The specific heat for water = 1 calorie/gram °C.
Purpose:
The purpose of this lab was to determine the energy content of different foods.
Hypothesis:
If different foods are burned, then their energy content can be found, because the energy will
be transferred to the water in the calorimeter because of the Law of Conservation of Energy.
Materials:
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Safety goggles
Food samples
Food holder
Can Calorimeter
Ring Stand
Ring Clamp
Water
Graduated Cylinder
Balance
Matches
Thermometer
Diagram of lab setup:
Procedures:
1. Get and put on safety goggles.
2. Measure water (approximately 50 ml) and put in can calorimeter.
3. Measure temperature of water.
4. Get food sample and put in food holder.
5. Measure mass of food and food holder.
6. Light food on fire and put close to bottom of can.
7. Wait for food to burn completely.
8. Measure temperature of water.
9. Measure mass of remaining food and food holder.
10. Empty water from can and throw away food remains.
11. Repeat steps 2-10 for remaining 3 foods.
Safety Considerations:
1. Wear safety goggles at all times.
2. Long hair should be tied back.
3. Close-toed shoes should be worn.
Data:
Marshmallow
Peanut
Potato Chip
Popcorn
Initial mass of food
and holder in grams
28.2 g
18.5 g
19.1 g
18.1 g
Final mass of burned
food and holder in
grams
Starting water
temperature in °C
25.2 g
18.0 g
18.4 g
18.0 g
21.9 °C
22.8 °C
23.7 °C
25.2 °C
27.1 °C
37.6 °C
37.3 °C
26.7 °C
Final water
temperature in °C
Calculations:
Marshmallow
Peanut
Potato Chip
Popcorn
Calculated mass of
water in grams
5.2 °C
50.0 g
50.0 g
50.0 g
Calculated ∆T in °C
5.2 °C
14.8°C
13.6°C
1.5°C
Calculated heat
energy gained by
water in J
Q = mc∆T
Calculated mass of
food burned in grams
1086.8 J
3093.2 J
2842.4 J
313.5 J
3.0 g
0.5 g
0.7 g
0.1 g
Calculated energy
content per gram of
food (J/g)
362.3 J/g
6186.4 J/g
4060.6 J/g
3135.0 J/g
Calculations for Marshmallow
1. Heat Energy = (mass of water) * (specific heat) * (change in temperature)
50.0 g x 4.184 J/g°C x 5.2 °C = 1068.8 J
2. Energy content per gram = Heat Energy / Mass of Burned Food
1068.8 J / 3.0 g = 362.3 J/g
Calculations for Peanut
1. Heat Energy = (mass of water) * (specific heat) * (change in temperature)
50.0 g x 4.184 J/g°C x 14.8 °C = 3093.2 J
2. Energy content per gram = Heat Energy / Mass of Burned Food
3093.2 J / 0.5 g = 6186.4 J/g
Calculations for Potato Chip
1. Heat Energy = (mass of water) * (specific heat) * (change in temperature)
50.0 g x 4.184 J/g°C x 13.6 °C = 2842.4 J
2. Energy content per gram = Heat Energy / Mass of Burned Food
2842.4 J / 0.7 g = 4060.6 J/g
Calculations for Popcorn
1. Heat Energy = (mass of water) * (specific heat) * (change in temperature)
50.0 g x 4.184 J/g°C x 1.5 °C = 313.5 J
2. Energy content per gram = Heat Energy / Mass of Burned Food
313.5 J / 0.1 g = 3135.0 J/g
Data Analysis
The food with the highest energy content per gram was the peanut.
The food with the lowest energy content per gram was the marshmallow.
1. One possible source of error in this lab was that energy was lost to the air because
the food wasn’t directly next to the can. Another area where error could have
occurred was in the measuring of the temperature because it was hard to read the
thermometer and the temperature dropped a lot when it was taken out of the can.
2. The calorimeter makes use of the law of conservation of energy because it
measures the amount of heat transferred to the water in the can from the burning
food.
3. Looking at the data from the peanuts and potato chip (high fat) compared to the
marshmallow and popcorn (high sugar), high fat food contains more energy than
high sugar food.
4. In this experiment, the peanut had the highest energy content. This makes sense
because the peanut burned the longest and had the highest fat content. High fat
foods have a higher energy content.
5. The peanut had 6186.4 J/g.
(6186.4 J/g) x (50 g) x (1/4.184 cal/J) x (1 Cal/1000 cal) = 73.93 Calories
Conclusion
The hypothesis for this lab was that if different foods are burned, then their energy content
could be found, because the energy will be transferred to the water in the calorimeter because
of the Law of Conservation of Energy. This hypothesis was supported because when the food
burned the temperature of the water increased.
The lab was related to the study of energy because we measured the change in temperature
using the calorimeter and used the heat calculation to determine the heat energy.
The data showed that high fat foods have more energy than high sugar foods which was
expected. The food with the highest energy content per gram was the peanut at 6186.4 J/g.
The food with the lowest energy content per gram was the marshmallow at 362.3 J/g. This
information could be used to help choose foods when more or less calories are needed and to
help choose more healthy foods. This information could also be used if heat was needed and
food was the only thing available to burn.