When you buy a bag of chips or whatever it will stay fresh for a long time but once you open the bag it will only last for a few days. How is this possible?

Question

Like there is air in the bag as well so how come it can last for longer period of time when sealed?

In: Earth Science

Answer 1

The “air” in the bag is almost pure nitrogen. By contrast, the air we breathe is only about 80% nitrogen, with a bunch of other things like oxygen, carbon dioxide, and water vapour. When you open the bag, you let in these other gases, and they’re what make the crisps/chips go soft and soggy.