Name:__________________________ Period: 1 2 3 4 5 6 7 Date:_____________________
Exploding
Corn Lab
Background Information:
According to The Popcorn Board, Americans today consume 17 billion quarts of popped
popcorn each year. The average American eats about 52 quarts of popcorn per year. The
science behind corn popping is as simple as boiling water. Each popcorn kernel contains starch
and water. The kernel needs to have a moisture content around 14% in order to have the fuel
to pop. The starch grains of the popcorn are enclosed in a pericarp, or seed covering. When
the kernel is heated, the starch grains gelatinize into a gooey substance and the water begins to
boil inside the pericarp and starchy endosperm. As the water temperature reaches the boiling
point of water, the water vaporizes and expands rapidly in volume.
The hard starch matrix holds until the pressure becomes too great at 135 pounds per
square inch, at which point the kernel bursts open and the endosperm expands in volume
because of the pressure difference. The water evaporates and the cooked starch granules are
dried out, making the endosperm light and crisp. If the moisture cannot escape, it gets
reabsorbed by the popped corn making it chewy and tough.
Pressure, explosions, and phase changes make popping popcorn a pretty cool science
experiment. This experiment will give you a chance to watch the action occur in front of your
eyes while you consider the overall energy and mass of the popcorn. Does the mass stay the
same, increase, or decrease as it goes from kernel to popcorn? How can you measure this
throughout the experiment?
Materials:
30 Popcorn Kernels
250mL Erlenmeyer flask
Toothpick
Ring Stand/Wire Mesh
Goggles
5mL of Vegetable Oil
Graduated Cylinder
Paper Towel
Tongs
.25g of NaCl
Aluminum Foil (10cmx10cm)
Bunsen Burner/Hot Plate
Triple Beam Balance
Lab Procedures:
1. Put on your safety goggles and gather all your materials at your lab station.
2. Take the 250mL Erlenmeyer flask. Make a cover for the opening of the flask using a
small square of aluminum foil.
3. Poke three or four small holes in the top of the aluminum foil with a toothpick.
4. Using the balance, find the mass of your flask with the foil lid and record the mass in
your data table for balance measurements.
5. Add mL of liquid vegetable oil to the flask.
6. Using the balance, find the mass of the flask, vegetable oil, and cover and record your
data in your data table.
7. Place 30 kernels of popcorn in a small graduated cylinder. Record the approximate
volume of the kernels in your data table.
8. Carefully remove the cover from the flask and add the 30 kernels to the flask.
9. Using the balance, find the mass of the flask, foil cover, vegetable oil, and popcorn
kernels and record that mass in your data table.
10. Set up a Bunsen burner and ring stand with wire mesh on the iron ring. Make sure your
Bunsen burner gas intake tube is securely connected to the gas nozzle and that the ring
is set about 3 in. above the barrel of the burner. Light the Bunsen burner to create a
flame that is no more than 3 in. high.
11. Using the tongs, move the flask across the flame to evenly heat the popcorn kernels.
12. As the popcorn kernels burst, remove the flask from the heat and then heat only gently
to pop the remaining kernels. Some kernels may not pop, so take care not to burn the
popcorn. What do you observe inside the flask as the kernels are popping? Record your
observations here?
13. Allow the flask to cool to room temperature. Use the balance to find the mass of the
flask, lid, and contents and record your data.
14. Record the approximate volume of your popcorn kernels by using the measurement
scale on the side of your Erlenmeyer flask.
15. Compare your results with another lab group in the class. Record the other data on
your chart in the section called “Results From Other Scientists.”
16. Pour your popcorn onto a paper towel. Sprinkle with NaCl for taste, and then feel free
to eat your final lab product.
17. Clean up your lab table and answer the follow up lab questions.
Data Table
My Results (g)
Results from Other
Scientists (g)
My Results (mL)
Results from Other
Scientists (mL)
Mass of Flask and Cover
Mass of Oil, Flask, and Cover
Mass of Flask, Cover, Oil,
and Popcorn Kernels
Mass of Flask, Cover, Oil,
and Popcorn Kernels After
Heat Expansion
Volume of Popcorn Before
Heating
Volume of Popcorn After
Heat Expansion
Post-Lab Questions
1. What was the overall mass of oil used for your experiment? Calculate this using your
measurements from your data table.
2. What was the mass of the popcorn kernels used in this experiment? Use your
measurements from your data table and the answer to question #1 to figure this out.
3. What was the mass of the popcorn kernels once they were popped? Use the measurements
from your data table to solve this problem.
4. What was the change in volume of the popcorn from kernel to when it popped?
5. Why do you think that some of the popcorn kernels did not pop?
6. How does this lab relate to the conservation of mass law? (Use at least 4 complete
sentences to answer)
7. How do your results compare with the information you received from other groups? Were
your results the exact same as other groups or different? Explain your answer?