I bought a usual bag of chips and took the plane. In the air, it seemed that it was pretty much expanded, as if it was going to explode.

I thought to myself: ok that's normal, the pressure in the plane is smaller than on the ground so $PV=nRT$ leads to the volume of the bag tends to be bigger in the airplane.

But one hour after landing, my bag was still very big, like it was in the airplane. It didn't get back to normal.

It was a one hour flight and the "external conditions" looked the same, I mean I didn't go from seaside to mountain or altitude or anything like that.

Any explanation for my bag of chips?! Thanks!


1 Answer 1


Answering isn't really possible since we don't know the exact conditions involved. A couple notes, though:

First, the bag is sealed at the factory, not where you bought it, so it's the pressure difference between your new location and the factory that matters.

Second, it doesn't take a lot of pressure difference to make a flimsy chip bag expand. You can drive up a mountain road for 5 minutes and cause the bag to expand. Look up the exact altitudes in the start and end points of your flight. They could easily be off by a few thousand feet depending on the area.

Third, temperature can play a large factor here. If the bag was in a cold store, then the end location of the trip is in a warmer place, the internal pressure could be higher for the same atmospheric pressure.

Again, we'd need more information to be sure exactly what was going on, but relative altitude and temperature are the two things I'd look at first.

  • $\begingroup$ hmmm I thought about this but all bags in the shops were normal and the same before the flight and after (same brand, shop at airport in landing), only my bag which went into the air. I thought that the air was colder in the airplane, but after 1 hour waiting for my suitcase at the airport it should have evened out $\endgroup$
    – Thomas
    Nov 11, 2015 at 22:47

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