TITLE:
Burn a Nut Lab
PURPOSE:
To witness the release of stored (potential) energy in food.
MATERIALS: ring stand, beaker, graduated cylinder, cardboard, thermometer, safety goggles, nut, soda can, 4
paper clips, matches, small cardboard square, 60 cm section of aluminum foil
INTRODUCTION:
In today's society, we are bombarded with nutritional information about the foods we eat. High on the list
of important information about these foods is their caloric content. In this laboratory exercise, we will use a
simple apparatus called a calorimeter to determine the amount of heat (calories) liberated when a nut is burned.
One calorie (termed a physicist’s calorie) is the amount of energy necessary to raise the temperature of
one gram of pure water by a temperature of one degree Celsius. One food Calorie = 1,000 (physicist’s) calories. It
is noted here that a kilocalorie (kcal) is the same as a food Calorie (sometimes called a big calorie or a nutritional
calorie).
Energy is stored in the bonds of large molecules; chemicals like gasoline and food are stored energy.
Stored energy is often called potential energy, because of its ability to do “work” of some type. Other examples
of potential energy would be an electric battery or a ball sitting at the top of a ramp. When energy is doing some
type of work, the energy is called kinetic energy. Kinetic refers to change or something is changing. Examples of
kinetic energy would be a battery connected to a motor and causing it to turn or ball rolling down a ramp. In this
activity, oxygen is a molecule that breaks up these large molecules, releasing energy. We call this combustion or
burning if it happens quickly. In your cells, the burning is much slower, and the potential energy is released into
kinetic energy more slowly, but oxygen is still needed. We call this "slow burning" cellular respiration.
Recall that the chemical reaction for respiration is represented by the following chemical equation:
C6H12O6 + 6O2  6CO2 + 6H2O + ATP energy released
PROCEDURE:
In this experiment, we will measure the potential food energy contained in a nut. Energy is stored in food in
chemical bonds. The gross energy value of a food can be determined by burning the food and measuring the kinetic
chemical energy produced. The amount of heat produced can be measured by how much it raises a known volume of
water.
A nuts consists of roughly 50% oil, and this oil is fairly flammable, and can be easily ignited with a wooden kitchen
match. In this exercise, we will burn a nut, and use this energy to heat a quantity of water contained in an aluminum
soda can. We can then calculate the amount of heat (in calories) released by the nut.
Each student is individually responsible for recording, analyzing, and calculating the data. One write-up
from the group will randomly be selected to be graded for the group- so check each other’s answers.
P1=Person #1- Principal Investigator, P2=Person #2= Technician, P3=Person #3=Recorder, P4=Person #4=
Maintenance Director
Safety goggles are required at each step in this lab. No horseplay whatsoever today, nor playing with
matches.
1.
P1: Use a nail to make three small holes evenly spaced apart in the sides of the can near the top. The can
will serve as your Calorimeter (a devise to measure calories).
2. P2: Open the end of the paper clip until it looks like a “C” shape. Repeat for the two other paper clips.
3. P3: Determine the mass of the empty calorimeter (without paperclips). Record the mass on your chart.
Hang the calorimeter from the ring stand with the paper clips inserted into the small holes you made in
your can. Suspend the can from ring clamp and adjusting to the proper height. See figure 1 (on the next
page) for a diagram of the set up.
Figure 1: Can hanging from ring stand with paper
clips
Figure 2: Nut on a paper clip
4. P4: Carefully add 100 mL of water, by measuring with a graduated cylinder, to the calorimeter through the
opening at the top.
5. P1: Determine the mass of the calorimeter plus the water (without paperclips) on the triple beam balance
and record in the data table and your student answer page.
6. P2: Insert a thermometer through the opening in a cardboard square. Place the thermometer through the
opening in the soda can. The thermometer should not be touching the bottom of the can, just
suspended in the water in the can.
7. P3: Measure the initial temperature of the water in the can and record on your answer sheet. Do not let
the thermometer touch the bottom of the can.
8. P2: Weigh a nut to the nearest 0.1 g on the triple beam balance and record this value in the table below.
9. P4: Make a stand for the nut by straightening out one end of a third paper clip. You will have to manipulate
the paper clip so that the nut will stand up. Gently press the end of the paper clip into the nut so that the
nut is suspended in the air. See Figure 2 for further help.
10. P3: Adjust the ring stand so that the bottom of the soda can is 3 cm from the top of the nut.
11. P4: Use the piece of aluminum foil to engineer a heating chamber so heat will not be lost to the
environment and will be directed towards the soda can calorimeter. It is up to you and your group to think
of a design that will limit the amount of heat lost. However, for something to burn, it needs air/oxygen. So
if you make your chamber airtight, the nut will not burn efficiently and less heat will be produced. If your
design allows too much air in and out, heat will be lost. But remember, the combusted gases (carbon
monoxide, carbon dioxide) must exit the heat chamber at the top.
12. P1: At this point, you are ready to ignite your nut. Raise your hand and wait till your teacher comes to your
table. Ignite the nut with a wooden match. The nut should be lit off to the side of the can.
13. P2: As soon as it begins to burn, quickly shift the nut on the paper clip beneath the can so no heat is lost.
Let the nut burn until it burns itself out. Place the blown out match on the black stand of the ring stand.
14. P3: Carefully monitor the temperature and record the highest temperature reached by the thermometer.
15. P4: After the nut has burned up completely, let it cool, then weigh the remains of the nut on the filter
paper and record this in the table below. Now crush the remnants of the nut between your fingers. What
seems to be left?
16. All members: Clean up your area after letting all your equipment cool down. Neatly place all of the
equipment on the counter next to your lab table.
Calculations: Each student will do this part. All work should be shown on the back of your student answer
page. Your work should be numbered as well as neatly written! No credit will be awarded for this section if
your work is hard to read or messy! Record all calculated values in the data table on your student answer page.
17. Calculate the heat produced by using the following formula add this to your data table:
heat (calories) = mass of water (g) x temperature change (°C).
18. Convert calories to kilocalories (food Calories) by dividing the amount you calculated above by 1,000 add
this to your data table
19. The metric unit for heat is not a calorie; it is a joule. One food Calorie (kcal) is equal to 4200 joules.
Determine the amount of joules your nut released and add this to your data table.
20. Calculate the mass of the nut that burned. To do this, subtract the mass that remained from the initial
mass of the nut.
21. Find the caloric value of the nut by dividing the kilocalories of heat produced by the mass of the nut of
that burned add this to your data table.
caloric value = Kcal / g of nut burned
22. Calculate your % error. See answer sheet for the actual food value of the nut add this to your data table.
% error = 100 x (your actual value - measured value) / actual value
Title: Burn a Nut Lab Student Answer Page
Purpose: To witness the release of stored (potential) energy in food
Name:
Date:
Period:
Directions: Be sure to show your work for problems 17-22 on the back side of this page. Your work should be
numbered as well as neatly written.
Conclusion Questions:
1. What type of energy is stored in the nut?
2. When the nut was burned, the stored energy was converted to what type of energy?
3. How close was your measured value to the actual value?
4. Analyze your calculations and determine the sources of error in your lab in order to explain the difference between the
measured and the actual value. What type of errors do you think may have occurred that would explain this difference?
5. Do you think this is a good method for determining the calories in food? How does the body create energy for food?
6. Since you don't need all the energy right away that is extracted from your food, how does your body store the energy for
later use?
Data Table:
Group Data for a Peanut
a) Mass of empty aluminum calorimeter:
b) Mass of aluminum calorimeter + water:
c) Mass of water (b-a):
d) Mass of nut before burning:
e) Mass of weigh boat:
f) Mass of nut after burning:
g) Mass of nut that burned
h) Initial temperature of water in calorimeter:
i) Final temperature of water in calorimeter:
j) Change in water temperature
k) Heat released by nut that was absorbed by water (calories):
l) Heat released by nut that was absorbed by water (kilocalories):
m) Heat released by nut that that was absorbed by water (Joules):
n) Caloric value
o) The actual caloric value is 5.6 kcal/g for a peanut, 5.7 kcal/g for a
cashew, and 6.1 kcal/g for an almond. Find your percent error.
13g
113.5g
1.4g
3.2g
.4g
25 degrees Celcius
35.1 degrees Celcius