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 sealed bag is nitrogen, which makes up some 78% or so of the outside air. When the bag is opened, the chips are exposed to oxygen, which starts the decaying process.