The Energy Inside A Peanut
Just about everything has potential energy stored in it. The problem is
releasing that energy to be able to do some work.
A tiny peanut contains stored chemical energy. When we eat them, the
stored energy is converted by our bodies so we can do work. We can also
use the energy in a peanut to heat a container of water.
What You'll Need
- A small bag/can of unsalted, shelled peanuts
- A cork
- A needle
- A large metal juice or coffee can
- A small metal can (like a soup can) with paper label removed
- A can opener
- A hammer
- A large nail
- A metal BBQ skewer (like the kind for kabobs)
- About a cup of water
- A thermometer
- Some matches or a lighter (ask an adult for help here)
- A piece of paper and pencil to record your observations
What to Do
- Carefully push the eye of the needle into the smaller end of the
- The gently push the pointed end of the needle into a peanut. If you
push too hard the peanut will break in pieces. If it does, use another
peanut. It's also better to have the peanut at a slight angle.
- Remove the two ends of the large juice can with the can opener. Be
careful as the top's and bottom's edge can be sharp!
- Using the hammer and nail, have an adult punch holes around the bottom
of the large can. These are air holes that will make the can act like a
chimney and will contain the heat energy focussing it on the smaller
- Remove the top end of the small can (if it is not already removed).
- Using the hammer and nail, punch two holes near the top of the small
can exactly opposite each other.
- Slide the BBQ skewer through the holes of the small can.
- Pour 1/2 cup of water into the small can and let it sit for an hour.
This will allow the water to be heated or cooled to room temperature. (Munch
on some peanuts while you're waiting.)
- Put the thermometer into the water and record the temperature on your
- Place the cork and peanut on a nonflammable surface. Light the peanut
with a match or lighter. Have an adult help you! Sometimes the peanut
can be difficult to light, so the lighter may be easier to use.
- As soon as the peanut has caught fire, immediately place the large
can around the nut. Balance the skewer holding the small can on the top
of the large can.
- Allow the nut to burn for several minutes or until it goes out.
- Stir the water with the thermometer and record the temperature
What You'll Discover
The chemical energy stored in the peanut was released and converted
into heat energy. The heat energy raised the temperature of the water in
the small can.
Try a couple of other experiments using different kinds of peanuts
or other kinds of nuts. Try:
- Raw peanuts
- Dry roasted peanuts
- Vacuum-packed peanuts
- Freeze-dried peanuts
- Try cashew nuts, Brazil nuts, pecans, walnuts or other kinds of nuts.
(Do they contain more energy than the peanut? Why or why not?)
You might want to try more than one peanut. You'll need extra needles.
Use four or five peanuts to heat the water. Is the temperature four or
five times higher?
Energy is measured in a unit called the Btu, which stands for British
thermal unit. A Btu is the amount of energy it takes to raise one pound
of water one degree Fahrenheit. Using math, you can figure out how many
Btu are in the one peanut. The plural of Btu is still Btu, not Btus.
First you'll need to find out how heavy 1/2 cup of water it. Use a
small scale and weigh the small can with nothing in it. Then weigh the
can with 1/2 cup of water in it. That will tell you how much the water
Then knowing how hot the water was, how many degrees its temperature
was raised, you can figure out roughly how many Btu are in the single peanut.
This will be an approximation because the entire peanut will not be completely
burned ... there is still some chemical energy left inside the partially
For example: If the water weighed four ounces (1/4 of a pound),
one Btu would raise the water temperature 4 degrees Fahrenheit. So, if
your water temperature increased by 10 degrees (70 degrees at room temperature
to 80 degrees), 10 divided by 4 would mean the peanut contained 2.5 Btu.
This is only an example of the math and will not be the same as your
One Btu equals approximately:
- One average candy bar (252 Calories)
- One hour of bicycling
- One blue-tip kitchen match
- 4/5 of a peanut butter and jelly sandwich