Sow What? - Girl Scouts Western Oklahoma

Sponsored By
Senior
STEM Kits
“Energy In Food –
How to build your
own calorimeter”
“Sow What?”
These activities were developed by Girl
Scouts - Western Oklahoma and correlate
with the themes and practices found
within the “Sow What?” Girl Guide book.
The STEM Kit in A Box contains the necessary supplies to complete each activity,
except where noted. You will use these
materials to help the girls earn their Journey badges as Seniors. These activities
MUST be completed as part of their Journey throughout the course of the year.
Each kit includes a leader guide that gives
background information on the activities.
It is recommended that the girls guide
themselves through these activities with
minimal guidance from you, the leader.
Chris Simon, STEM Coordinator
Girl Scouts – Western Oklahoma
csimon@gswestok.org
Phone: 405-528-4475 or 1-800-698-0022
This kit is provided through an award from the Oklahoma NSF EPSCoR program
and is based on work supported by the National Science Foundation under Grant No. IIA-1301789.
Project title: “Adapting Socio-ecological Systems to Increased Climate Variability.”
Any opinions, findings & conclusions or recommendations expressed in this material are those of the author(s)
and do not necessarily reflect the views of the National Science Foundation. www.okepscor.org
Sponsored By
OK NSF EPSCoR Content Reviewers: Dr. Jody L. Campiche, Assistant Professor of Agricultural Economics and
Extension Economist, Oklahoma State University; Dr. Renee McPherson, Associate Professor of Geography and
Environmental Sustainability and Girl Scout, University of Oklahoma
Senior
STEM Kits
“Sow What?”
“Energy In Food –
How to build your
own calorimeter”
Have you ever wondered how nutritionists know
how many calories a certain food contains? In
this project, you'll learn a method for measuring
how much chemical energy is available in
different types of food. You will build your own
calorimeter to capture the energy released by
burning a small food item, like a nut or a piece of
popcorn. This project gives a new meaning to
the phrase "burning calories."
Objective
The goal of this experiment is to determine the
amount of chemical energy stored in food by
burning it and capturing the heat given off the
food in a homemade calorimeter.
Background information:
Eating a balanced diet is fundamental to good health.
This project will give you a chance to learn about how
much energy your cells can extract from different
types of food.
You know that 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 energy that your cells can use
and store.
In this project, you will learn a method for measuring
how much chemical energy is stored in different
types of food. You will oxidize the food much more
rapidly by burning it in air. You'll use a homemade
calorimeter to capture and measure the heat energy
released by burning. The basic idea of a calorimeter
is to capture the released heat energy with a reservoir
of water, which has a high capacity for absorbing
heat. The temperature of the water reservoir is
measured at the beginning and at the end of the
experiment. The increase in the temperature (in
Celsius (°C)) multiplied by the mass of the water (in
grams (g)) will give you the amount of energy in
calories as captured by the calorimeter.
Senior
STEM Kits
“Sow What?”
“Energy In Food –
How to build your
own calorimeter”
A Word about Calories
Calorie (cal) - Calorie has become a household word. Ask 100 people what a calorie is, and most will tell
you it is “the thing in food that makes me fat.” Calories have gotten a bad reputation and are considered
by many to be the enemy. Few people truly understand what a calorie is and why it is so important to
their bodies.
By definition, a calorie is the amount of energy it takes to raise the temperature of 1 gram of water by 1
degree Celsius. The important word to take away from this definition is ENERGY. Calories measure the
ENERGY that fuels our bodies, much like gasoline fuels our cars. Without sufficient energy, our heart
would not beat, our lungs would not function, and our brain would not work. Many of us have no idea how
many calories our bodies needs just to exist.
When people talk about the calories in food, what do they mean? A calorie is a unit of measurement, but
it doesn't measure weight or length. A calorie is a unit of energy. When you hear that something contains
100 calories, it's a way of describing how much energy your body would get from eating or drinking it.
Senior
STEM Kits
“Energy In Food –
How to build your
own calorimeter”
“Sow What?”
Are Calories Bad for You?
Calories aren't bad for you. Your body needs energy. But eating food that contains too many calories and not
burning enough of them off through activity, can lead to weight gain; that is, your body will gain more energy
than it loses.
Most foods and drinks contain energy. That energy is measured in calories. Some foods, such as lettuce,
contain few calories (1 cup of shredded lettuce has less than 10 calories). Other foods, like peanuts, contain a
lot of calories.
Children come in all sizes, and each child’s body burns energy (measured in calories) at different rates, so
there isn't one perfect amount of calories that a child should eat. However, there is a recommended range for
most school-age children is between 1,600 to 2,200 calories per day.
When girls reach puberty, they need more calories than before, but they tend to need fewer calories than
boys. As boys enter puberty, they may need food and drink with as many as 2,500 to 3,000 calories per day,
especially if they are very active. But whether they are girls or boys, children who are active and move around a
lot will need more energy input than children who don't.
Most children don't have to worry about not getting enough energy in food and drink because the body and
feelings of hunger help regulate how much a person eats. But children with certain medical problems may
need to make sure they eat enough calories. Children with cystic fibrosis, for instance, have to eat high-calorie
foods because their bodies have trouble absorbing the nutrients and energy from food.
Children who are overweight might have to make sure they don't eat too many calories. (Only your doctor can
say if you are overweight, so check with him or her if you're concerned. And never go on a diet without talking
to your doctor!)
If you eat more than your body needs, the excess energy is converted to fat. Too much fat can lead to health
problems. Often, children who are overweight can start by avoiding high-calorie foods such as sugary sodas,
candy, and fast food, and by eating a healthy, balanced diet. Exercising and playing are really important, too,
because activity burns energy.
Senior
STEM Kits
“Sow What?”
“Energy In Food –
How to build your
own calorimeter”
Materials:
How the Body Uses Calories
Some people mistakenly believe they have to burn off all the energy they eat or
they will gain weight. This isn't true. Your body needs some energy just to operate in
order to keep your heart beating and your lungs breathing. A child’s body also
needs calories from a variety of foods to grow and develop.
You can burn off some calories without even thinking about it – by walking your dog
or making your bed, but it is a great idea to play and be active at least 1 hour a day.
However, it is a great idea to play and be active for at least an hour a day. That
means time spent playing sports, just running around outside, or riding your bike. It
all adds up. Being active every day keeps your body strong and can help you
maintain a healthy weight.
Watching TV and playing video games won't burn many energy at all, which is why
you should try to limit those activities to one to two hours per day. A person burns
only about 1 calorie per minute while watching TV--about the same as sleeping!
Key Terms
Kilocalorie (kcal) - The term used to represent the amount of energy required to
raise the temperature of a liter of water one degree Celsius at sea level.
Calorimeter - An instrument for measuring the amount of heat released or
absorbed in physical and chemical processes.
Oxidation – In chemistry, the term “oxidation” means the addition of oxygen to a
compound. Examples of oxidation reactions include burning and rusting.
Recommended Dietary Allowance - The levels of intake of essential nutrients that
are judged by the Food and Nutrition Board on the basis of current scientific
knowledge to be adequate to meet the known nutrient needs of practically all
healthy persons.
(For a diagram and
instructions on assembling,
see procedure, below)
• Two tin cans, one larger
than the other
• Wooden dowel, pencil, or
other rod-shaped support
• Cork
• Needle or wire
• Hammer and nail
• Graduated cylinder
• Water (preferably distilled)
• Digital thermometer
(calibrated in °C, range
20–100 or greater)
• Safety glasses
• Aim and flame lighter
• Digital scale (calibrated in
grams, for determining
energy content per gram of
food)
• Pie tin
Also required are the
following that need to be
supplied by you, or your girls:
• Food items to test (dry
items will obviously work
better); for example:
° Roasted cashew nuts,
peanuts or other whole nuts
° Pieces of popcorn
° Marshmallows
° Small pieces of bread
° Dry pet food
Senior
STEM Kits
“Sow What?”
“Energy In Food –
How to build your
own calorimeter”
1. You have been given two cans to build your
calorimeter. They should nest inside one another.
The smaller can needs to sit high enough so that you
can place the cork, needle and food item beneath it.
2. The top and bottom have been removed from the
larger can so that you have a cylinder open on both
ends.
Procedure
3. The holes drilled at the end of the larger can
indicate the bottom (this is to allow air in to sustain
the flame).
4. The holes in the smaller can are used for the
support rods (the meat skewers) to pass through.
(NOTE: The diagram labels the support as a glass rod,
we are using a meat skewer in its place.)
5. Grasp the wire and push one end into the cork. You
will impale the food to be tested on the other end of
the wire. (NOTE: Be careful not to stab yourself.)
6. The smaller can will hold the water to be heated by
burning the food samples. Use the graduated
cylinder to measure how much water you use; the
can should be about half-full.
Constructing the
Calorimeter (refer to the
diagram above).
(NOTE: All of the drilling and cutting has been done
for you ahead of time. You will only need to
assemble the calorimeter as directed below.)
7. Put the supporting rod in place through the two
holes.
Safety note: Adult supervision is required! As
with any project involving an open flame, there
is a fire hazard with this project. Make sure you
work on a nonflammable surface. Keep long
hair tied back. Be careful handling the items
used in this experiment as they may be hot!
Wear safety glasses!
Senior
STEM Kits
“Sow What?”
“Energy In Food –
How to build your
own calorimeter”
1. Weigh each of the food items to be tested
and record the weight. Make sure to tare, or
zero, your scale each time before weighing the
items.
10. Carefully remove the small can by holding the ends
of the supporting rod and place it on a flat, heat-proof
surface (another pie tin). BE CAREFUL--the can will be
hot.
2. Fill the small can about half full with a
measured amount of distilled water.
11. Carefully stir the water and measure the final
temperature (Tfinal). Make sure the thermometer has
reached a steady level before recording the value.
3. Measure the initial temperature (Tinitial) of
the water.
4. Impale the food item on the wire.
5. Have your calorimeter pieces close at hand
and ready for use.
6. Place the cork on a non-flammable surface
(the pie tin).
7. Light the food item on fire using the Aim ‘n’
Flame provided. (Note: the nuts may take
awhile to catch fire.)
8. When the food catches fire, immediately
place the large can around the cork, and then
carefully place the smaller can in place above
the flame.
9. Allow the food item to burn itself out.
12. When the burnt food item has cooled, carefully
remove it from the needle (or wire) and weigh the
remains.
13. Repeat Steps 2–12 for all of the food items. It's a good
idea to repeat the measurement with multiple samples
of each food item to ensure consistent results. Make
sure you use the exact same amount of water for all
experiments.
14. Analyze your data. Calculate the energy released per
individual food item in calories, and the energy per unit
weight of each food item in calories/gram. From your
individual results, calculate average values for each food
type (see the formula below).
15. Discuss your results.
16. ASK: What items had the highest energy/unit weight?
What items had the lowest? Did any results surprise
you? How?
Senior
STEM Kits
“Sow What?”
“Energy In Food –
How to build your
own calorimeter”
Formula
The temperature of the water reservoir is measured at the beginning and at the end of the
experiment. Make sure you use the same exact amount of water for each experiment. The increase in
the temperature (in Celcius (°C)) times the mass of the water (in grams (g)) will give you the amount
of energy captured by the calorimeter in calories. We can write this in the form of an equation:
where:
Qwater = mcΔT
• Qwater is the heat captured in calories (cal)
• m is the mass of the water in grams (g)
• c is the specific heat capacity of water, which is 1 cal/g°C (1 calorie per gram per degree Celsius)
• ΔT is the change in temperature (the final temperature of the water minus the initial temperature of
the water) in degrees Celsius (°C)
Let's work through an example to make sure
that the equation is clear. (We'll use made
up numbers for the example. You'll have to
try the experiment for yourself to get actual
measurements.) Let's say we start out with
100 g of water in the calorimeter (m = 100
g). The initial temperature of the water is
20°C. After burning up a small piece of
food, we measure the water temperature
again and find that the final temperature is
24°C. Now we have all of the information we
need to calculate the amount of heat
captured by the calorimeter:
Now you can see why the specific heat capacity of water
has such strange units (cal/g°C). Notice that the grams
(g) from the mass of the water and the degrees Celsius
(°C) from the change in temperature cancel out with the
grams (g) and degrees Celsius (°C) in the denominator of
the units for specific heat. That way you are left with
units of calories (cal), which is what you want.