On our quest to understand Chemistry, chemical reactions, and properties of matter I had to ask the one question that many get stumped on, “Is air matter?” Selena didn’t take long to answer my question with, “Yes, air is made of molecules.”
I handed Selena an empty dry water jug with the cap on it and asked her what was inside it. At first she said, “Nothing.” I questioned her answer, and she thought about it for a minute or two and announced, “Air, there is air inside.” I again asked her if air is matter? How can we prove rather it is matter or not? Selena thought a bit and asked if we could heat the air up? I asked her to remind me of the two environments she can think of that will change matter. She answered with “Heat and Cold.” We then decided that maybe if we made the air cold we could see if it is indeed matter.
We placed the jug in the refrigerator. At this point Selena truly had no ideas or hypothesis as to what would happen, making this simple experiment even more mysterious for her. Then we went about our normal morning routine.
As I served up lunch I had Selena retrieve the water jug out of the refrigerator, her first observations were the now indentations of the bottle. As we sat down to eat lunch I had her place the jug in the middle of the table. I asked her what she thought had happened to the air in the jug to make it sink in like that? Selena didn’t take long before she answered, “The cold made the molecules in the air slow down making them bind together.”
As we ate our lunch we began to hear, “POP”, “POP”, “POP”. Selena was excited to see that the indentations in the jug had now popped out and looked like the jug looked like it did when we put it in the refrigerator. Again I asked her now what has happened to the air in the jug? She quickly thought about it and answered, the molecules warmed up and got bigger?” I asked her if by getting bigger did she mean expanded? She agreed that is what she meant. So now I asked is air matter? She came back to her first answer, “Yes, air is definitely matter because it has molecules.” I corrected her answer of the matter getting bigger and explained that as the molecules heated up they became faster again, breaking apart expanding in the space to make the bottle pop back to it’s original shape.