When microwaving a bag of popcorn, why doesn’t the first kernel that is popped burn by the time the last kernel is popped?
In: Chemistry
Kernels burn because they get too hot.
They get too hot because they get so much heat.
They get so much heat from water vapour.
Water vapour comes from exploded kernels and inside.
Exploded kernels help accelerate the rise in temperature outside as their water vapour is dissipated amongst all (neighbouring) kernels.
There is very little water vapour outside the kernels initially. All of it is inside.
Only the water inside the kernels can heat up due to the microwave.
Liquid water can only get to 100 deg C. Water vapour is not limited in temperature.
When there’s a lot more water vapour around as most kernels have opened, the outside temp can get very high and either directly burn opened kernels or the little butter/oil that was added for taste also starts heating up and burns them from below.
That’s why, Eli.
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