Ask A Scientist Chemistry Archive

Question:
While watching the Super Bowl this past Sunday, I made some popcorn
to ease my stress.  I was wondering what makes popcorn "pop"
and why is it larger after popping?  If someone would be kind
enough to answer this perplexity, it would make future Super
Bowl experiences more fulfilling.
 chris w stokes

Answer 1:
I feel honored that questions like this are being asked in the chemistry
section.  For whatever reason you think it's a chemistry question...?
I seem to remember from my biology days that corn kernels are loaded
with something called 3N endosperm and water.  When subjected to intense
heat, KAPOW!  Popcorn.  Try the biology section with this too.  If I'm
wrong with the contents of the kernel, I'm sure I'll be corrected.
After hearing that, you'll never look at popcorn the same again, will ya?
:)
-Joe Schultz
 
Answer 2:
The active "pop" agent is, of all things, water.  As the kernel is
heated, the water is heated to steam and pressure builds up in the
kernel.  When the pressure exceeds the strength of the kernel
covering, the seed covering breaks and "POP!"  When this happens, the
kernel contents (mostly starchy endosperm) expands to form a fluffy,
white, and delicious piece of popcorn.  By the way, I mostly hang out
on the Biology board and am honored to answer a question on the
Chemistry board.--Brian