White vs. Yellow Popcorn: Is there a Difference?
Name: ________________________________
Date: ____________
Introduction: Each kernel of popcorn contains a small drop of water stored inside a
circle of soft starch. The soft starch is surrounded by the kernel's hard outer surface.
As the kernel heats up, the water begins to expand. Around 212F the water turns into steam and
changes the starch inside each kernel into a superhot gelatinous goop. The kernel continues to heat to
about 347F. The pressure inside the grain will reach 135 pounds per square inch before finally
bursting the hull open. As it explodes, steam inside the kernel is released. The soft starch inside the
popcorn becomes inflated and spills out, cooling immediately and forming into the odd shape we know
and love. A kernel will swell 40-50 times its original size!
Purpose: To investigate any differences between white and yellow popcorn.
Materials: yellow and white popcorn, vegetable oil, 2-250 mL Erlenmeyer flasks, aluminum foil, hot
plate, balance, goggles
Procedure:
1.
2.
3.
4.
5.
6.
Plug in the hot plate and set it to medium (approximately 250 degrees.)
Select and weigh 20 kernels of one type of popcorn. Record on the data table below.
Add 1 full pipette of vegetable oil and the 20 kernels to an empty, dry 250 mL Erlenmeyer flask.
Determine the mass of the flask, oil, and popcorn and record on the data table below.
Cover the flask with a piece of aluminum foil. Puncture a small hole in the aluminum foil.
Place the flask on the hot plate. Remove it when most of the kernels have popped. Do not burn
the popcorn.
7. Carefully remove the aluminum foil from the top of the flask so all of the steam vents out.
8. Allow the flask to cool for a few minutes, and then weigh the flask and contents. Record on the
data table below.
9. Save the popcorn on a paper towel at your lab bench. Do not eat the popcorn!
10. Repeat using the other type of popcorn.
11. Compare the two types of popped corn in terms of shape and size. Record your observations
below.
12. Throw away the popcorn and wash the flasks thoroughly with soap and water using a brush.
Data:
Type of popcorn used
Type of popcorn used
Mass of the unpopped
kernels (g)
Mass of the flask, oil, and
unpopped kernels (g)
Mass of the flask, oil, and
popped corn (g)
Mass of the unpopped
kernels (g)
Mass of the flask, oil, and
unpopped kernels (g)
Mass of the flask, oil, and
popped corn (g)
Observations:
Yellow:
White:
Calculations:
1. Calculate the mass of water lost from the popcorn by comparing the mass of the flask and oil with
the popped kernels to its mass with the unpopped kernels.
Yellow:
White:
2. Calculate the percent of water in your popcorn using the mass of water lost as the “part” and the
mass of the original unpopped kernels as the “whole”, and record the percent on the chalk board.
Yellow:
White:
3. Calculate the class’ average percent water for both types of popcorn and record here:
Yellow: _____________%
White: _____________%
Conclusion Questions:
1. How did this lab use the law of conservation of mass? Be specific.
2. In your opinion, is there a significant difference between the white and yellow popcorn? Use your
data about the water content of the popcorn and your observations to back up your opinion.