Pressure in Popcorn

Pressure in Popcorn

Lab Report by Brady Pauken

       In this experiment, we were attempting to measure the pressure that it takes to pop a popcorn kernel while heating it in oil over a burner. We measured the mass of the kernels, and with this we will be able to determine the pressure that was necessary to pop them. The popcorn pops because of water inside of the kernels that boils and then pops because of the pressure inside.

Data Table:

5 mL of water- 32.34 grams
30 kernels used in total- 4 grams
Water Displacement- 8 mL of water
Displaced water of Kernels- 3 mL (8mL - 5mL)
Weight before popping- 120.5 grams (beaker, oil, kernals)

Final Weight- 118.5 grams
End result- 20 popped kernels, 10 unpopped

Procedure and Work:

First I found the mass of H20 loss: 120.5 - 118.5 = 2 grams

I then divided this by the mass of a mole of water: 2 / 18 = 0.11 mole H20

I then calculated that 3 mL of water is .003 L of water

From our work in class, I also know that the boiling of the oil we used is 498 Kelvin

Next I use these numbers in the PV=nRT equation to determine the pressure: P = nRT / V

P = (0.11 moles)(0.0821)(498 K)
----------------------------------------     = 1,499 atm 
                   .003 L

Finally I divided 1,499 atm by the number of popped kernels (20) to get about 80 atm, which I am sure is incorrect.

Pictures:

Burnt Un-Popped Kernels

Contents of the Beaker Post-Popping

Steven Nakamura Measuring Mass

Questions:

6. I think that all of the kernels did not pop for two reasons. The first reason might be due to a lack of water in the un-popped kernels. The kernels need water inside of them to heat up in order to pop. If a kernel lacks this water it will not be able to pop. I believe a second reason could be because our temperature was too high. As you can see in the pictures, most of our kernels were burnt, and perhaps this hinders their ability to pop.

7. As stated above, I believe that our temperature could have affected the outcome of the experiment because we burned many of our kernels. If I were to do this lab again, I would use a lover temperature, as well as more oil, because another problem may have been a lack of oil coating the kernels thoroughly. The kernels need to be covered in oil do spread the heat and distribute it evenly.