What Makes Popcorn “POP”?
If we examine a single kernel of popcorn and compare it with a grain of ordinary corn, two differences can be easily noted. First, the kernel of popcorn is more rounded than that of ordinary corn. Second, the coat on the popcorn is thicker and tougher. Both of these characteristics are important in the popping of corn. You will investigate the conditions and results of corn popping.
Procedure:
1. Examine the popcorn. Make as many observations as you can.
2. Select two samples of popcorn, each containing 3 kernels. Determine the mass of each sample of 3 kernels and record the answer in grams. Calculate the average mass of one kernel in each sample and record your results in grams
3. Place one kernel in a flask and place it on the hotplate.
4. Wait for the kernel to “pop” then determine the mass of the sample and record your result on the board in grams.
5. Average the mass of a single kernel.
6. Take a second kernel, but before heating, carefully pierce the seed coat of each kernel with a pin.
Reaction:
How can we account for the loss of mass of the popped kernel? The loss represents water, which has escaped “explosively” from the kernel as steam. The white starch grains “fluff-up” as the trillions of water molecules fly out of the kernel and burst through the seed coat of the kernel.
Questions:
1. Compare the average mass of a popped kernel with that of an unpopped kernel. If 18g of water has 600,000,000,000,000,000,000,000 molecules of water, how many molecules water escaped from one average kernel?
2. What happened to the popcorn that was pierced before heating?
3. Which chemistry concepts are involved in this experiment?