Energy in the Food We Eat
Name: ___________________________
Group:_____________
The energy that keeps your brain and body going comes from the food you eat. Your digestive system
and the cells in your body break down the food and gradually oxidize the resulting molecules to release
the chemical energy stored in them and use it to power the cells and your body.
You probably have heard a lot about the word “calories”, especially if you are watching your diet.
However, what you probably didn’t know is that “calorie” spelled with a lower-case “c” and “Calorie”
spelled with a capital ‘C” are two different things. The large Calorie (food Calorie, or dietary Calorie),
which is what you see on all food labels, actually equals 1000 “small calories”! 1 Calorie = 1000 calories,
or 1 kcal.
Now that you know the difference between “Calorie” and “calorie”, have you ever wondered how
nutritionists know how many Calories per serving a certain food contains? In this activity, you'll learn a
method used for this kind of measurement. The method is called “calorimetry”, which is a technique for
measuring the amount of thermal energy. A “calorimeter” is a device used to make such a
measurement. In this activity, you will build a calorimeter to measure the amount of energy in a peanut.
To do so, you literally burn a peanut, which gives a whole new meaning to the phrase "burning Calories."
Objective
The goal of this experiment is to determine the amount of Calories available from a peanut. The heat
released from burning the peanut is used to melt ice cubes in a pop can. By measuring the mass of ice
melted and knowing how much thermal energy it takes to melt 1 gram of ice, the amount of energy
released from burning a peanut can be calculated.
Here’s what you do:

Place a piece of aluminum foil on the table top to protect the surface. Fold the edges to make a
shallow tray. If the peanut falls off the holder, the edges should keep it from falling on the floor.

Set the peanut on the paper clip stand as shown. This will be demonstrated in class.

Fill the "POP" can about 1/4 full of ice.

Light the peanut by holding the match directly below the
peanut. It might take a couple of matches to get the
peanut burning.

While one group member is trying to get the peanut
burning, another group member should pour off any
water that has collected in the pop can. There should be
as little water in the can as possible when the peanut
starts to burn.

As soon as the peanut starts to burn by itself, the match
should be removed and the pop can should be held about
5 centimeters (2 in.) above the burning peanut.

Gently swirl the can as long as the peanut is burning (if
your peanut goes out prematurely you will have to re-ignite it).

When the peanut has burned as completely as it is going to, pour all the water in the pop can into a
graduated cylinder and measure the volume of water from the ice that has melted.
1. Volume of water from melted ice
______________________ mL
2. Calculate the mass of water from melted ice (density of water: 1.0 g/mL). Show your work.
3. Calculate the thermal energy required to melt the ice. It takes 80 calories (“small calories”) to melt 1
gram of ice. Show your work.
4. Find the chemical energy released from burning the peanut in the unit of dietary Calorie (“big
calories”). Remember that 1 dietary Calorie = 1 kcal or 1000 small calories.
5. On average, there are about 40 peanuts in a 1-ounce serving. Calculate the Calories in an average
serving of peanuts using your value of Calories in one peanut. Show your work and report your
answer on the board.
6. How does the class average compare to the information on the label? If they are different, what
could have contributed to the difference?
7. What improvements do you think real calorimeters have over our homemade version?
Burning and metabolism
The term “burning” in general terms means to combine with oxygen. Since most common materials that
burn contain mostly carbon, hydrogen, and oxygen, the products of combustion are generally carbon
dioxide and water. For an example, let's look at the burning of glucose (C6H12O6).
C6H12O6
glucose
+
6 O2
oxygen
from air
→
6 CO2
carbon
dioxide
+
6 H2O
water
The equation above also describes what happens during aerobic respiration. When we eat food (a candy
bar or a baked potato, for example), the carbohydrates in the food are digested and eventually turn into
glucose. We breathe in oxygen from the air. The glucose burns (slowly – no flame, of course) in our body
and releases energy. We exhale the carbon dioxide and water vapor and the energy from the reaction is
harvested by cells and used to fuel our body.
1. What state (solid, liquid, gas, plasma) are each of the molecules in during the above reaction?
2. Which molecule has a larger molecular weight, water or carbon dioxide?
3.
a. Compare the molecular weight of Oxygen, the gas you inhale, to Carbon Dioxide, the gas you
exhale.
b. Where does the extra mass come from?
4. Why do you think there is a 6 in front of the O2?
Food Labels: Metric unit Vs. English unit
Just like the United States, many countries require nutrition labels of ingredients and the amount of
Calories on foods and beverages. However, unlike the United States, they use metric units instead of
English units. We have several food packaging that we kept from our trips abroad. Let’s use them to find
the conversion factors between the metric units and the English units.
1. Try to identify what country each package or can is from.
2. Notice each package or can has nutrition information on the label.
a What unit are the other countries using for Calories?
b
Find three labels that include energy in both Calories and kilojoules. Identify the labels and
divide the kilojoules by the Calories.
c
These ratios, conversion factors, should all be the same. Are they? If not, which label is the
most accurate? 1 Calorie = 4.184 kJ.
3. Ritter Sport labels
a. How many grams of chocolate are used for the information on the nutrition label of the US
marketed package?
b. How many grams of chocolate are used for the information on the nutrition label of the
German marketed package?
c. Are these the same? Any ideas why?
4. Use the U.S. marketed Ritter Sport Label to answer the following questions. Show your work for
each question.
a. Calculate the actual number of servings in one package to the nearest 10th of a serving. Hint:
It is not 3.0.
b. Calculate the number of Calories contained in the entire package
c. Calculate the number of grams of fat in the entire package.
d. Calculate the number of grams of sugar in the entire package.
e. Calculate the number of grams of protein in the entire package.
5. Compare your answers to 4.a – e to the German marketed package. Do your values match?
6. What is the word for Saturated fat in German?
7. Is this chocolate bar a good source of any type of vitamin/mineral? If so, which one(s) and how
much of our daily value does it provide?
8.
When does the German marketed chocolate package say it expires?
Powerade® Sport Drinks. Examine the nutrition labels for Powerade Ion4 Mountain Berry Blast and
Powerade Zero Mixed Berry Sport drinks. In a commercial, it was claimed that both drinks helps replace
4 electrolytes lost in sweat.
1. Could you identify these 4 electrolytes? (Identify them as the chemical elements).
2. Identify the compound(s) that contain each electrolyte in Powerade sport drinks.
3. How many Calories/serving does the Powerade Ion4 and Powerade zero provide, respectively?
4. What is the major difference in the ingredients between the two drinks?
5. Based on your answers for Q#3 and Q#4, answer the following questions
a. Are electrolytes a source of energy in Sport drinks? Justify your answer.
b. If the answer is “No” in part a, what do you think is the source of Calories in Powerade Ion4?
How many Calories does each gram of the substance provide?
Pedialyte®. Examine the labels for Pedialyte and answer the following questions.
6. What electrolytes are in Pedialyte? (Identify them as the chemical elements).
7. Identify the compound(s) that contain each electrolyte in Pedialyte.
8. Does Pedialyte provide any electrolytes that are not present in the Powerade sport drinks? If so,
name them.
9. Are electrolytes the only nutrients Pedialyte supplies? Justify your answer either way. Be specific.
Protein bar/energy bar. Search online for the nutrition facts for your favorite protein bar/Energy Bar.
Answer the following questions based on the nutrition facts you find.
1. Write down the name of your favorite bar.
2. The bar provides _________ Calorie/serving; Out of these Calories, _______ Calories come from fat.
3. _________ total grams of fat are in each serving. How many Calories does each gram of fat supply?
4. List the types and amount of different types of fats found in your favorite bar.
5. What do you know about the different types of fat listed in the nutrition facts? Include everything
you know: the good, the bad and the ugly.
6. Many people associate “Calories” with fat rather than energy. Can you find evidence on the labels
that Calories are not just a measure of fat? Please explain clearly your evidence and why it shows us
that Calories are not just a measure of fat.