Chemistry Blog

The Pressure of Popping Corn


popcorn-close-upEssential Question: How do the gas laws, in combination with the structure of popcorn, explain popcorn’s “popping” when heated?

Popping popcorn involves heating the kernel until it is so hot that it causes the inside of the kernel to release moisture and pop inside out. The ideal gas law is used in this experiment. The ideal gas law relates the variables of pressure, volume, temperature, and number of moles of gas within a closed system.

The ideal gas law takes the form:

PV = nRT

P = Pressure of the confined gas in atmospheres

V = Volume of the confined gas, in liters

n = Number of moles of gas

R = Gas Constant, 0.0821 L·atm/mol·K

T = Temperature in Kelvin

Recorded Lab Results:

Brand A

Average mass kernal popped- .62 g
Average mass popped kernal- .66 g
Mass H20- .4 g

Brand B

Average mass kernal popped- .64 g
Average mass popped kernal- .69 g
Mass H20- .5 g

D= m/v
n= moles H20
T= 225 degrees celsius
H20= 1 g/mL
v= .4

The process of popping popcorn is not that complex. When you heat popcorn kernals the moisture from inside the kernel becomes so hot that it needs to be released and when it is released the kernal flips inside out. Some kernels do not pop because popcorn kernels contain an optimal hull structure that allow the kernel to explode. The leaky hulls prevent the moisture pressure buildup needed for the kernels to pop. The relationship between pressure and temperature the ideal gas law. As the pressure goes up so does the temperature, and vice-versa. As the temperature of the popcorn goes up the pressure increases.

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