Crushing can? Air pressure? Sounds like a lot of fun. This Simple Science Experiment is one of my coolest that I use in class, but it requires some safety measures to get it done right. You’ll be using a stove top electric burner (with adaptations for a gas powered stove), so your parents need to be involved.
I don’t want to get into the explanations yet, but just know you will be having a soda can crush itself in a very scientifically cool way.
- Several empty and clean soda cans
- an electric stove (I will give alternate instructions for a gas stove)
- tongs (these are very important)
- a big bowl
- ice cubes
Procedure for an electric stove top:
- Fill a bowl with icy water. Make sure there is enough water and ice to cover at least half of the can. Put this next to the stove
- Practice holding the can with your tongs so you can pick it up. Grab the can near the bottom
- Practice putting the can “open end” into the bowl of water in one quick motion. This is the move you will do in a couple of minutes; you just want to get it right!
- Put two tablespoons of water into the clean soda can
- Turn your electric stove on to high heat (choose one of the elements in the front)
- Put the can directly onto the electric element (yes, the can will be ok… it will not burn!)
- Leave the can on the element until you see steam coming out of the top of the can for at least a minute
- Using the tongs, grab the can near the bottom and with one swift move, turn it over so the open end goes into the icy bath!
Procedure for a gas range:
- You will do all the above except at step #6, you will use a pan with a little bit of water in it. You will put the soda can into the water bath (covering just the bottom inch of the can)
- Let the water boil like in step #7 above; but realize this process takes much longer to heat up as opposed to putting the can right on the electric stove
- Proceed with step #8 above
The second the can collapses in on itself is one of the best demonstrations that I do in my classes each year. It is a little startling at first, but it is a pretty effective experiment.
A few principles are working here. First, you are boiling the water in can, which turns it into a gas. Important to note is that the gas (steam) is taking up a lot more room than the liquid form of water. (Gas expands when it turns from a liquid). So if we were to cool that steam, it would shrink into a liquid. Hold onto that thought.
Second, you need to know that Nature doesn’t like a vacuum, or a lack of air. It tries to fill it up. Like when you use a plunger on the floor, you first push out all the air, and then it “sticks” onto the floor. Air is trying to get into the plunger, but it can’t so it makes a “suction.” Ever try to stick a cup to your mouth? You suck out the air and then it sticks to your face. (Please try this if you haven’t, you don’t want to miss out on a big part of childhood).
The big picture? Air goes from high air pressure to low air pressure (or more air to less air). If something gets in the way, it makes a push.
How does this relate to the crushing can? The steam pushes out all the air in the can; notice steam is coming out? It just pushed out all the air. When you quickly move the can to the icy water, it immediately cools the steam, turning it into water (and it shrinks doing so). This also means, NO AIR is in the can! It is a vacuum. And so air outside tries to get into the can, and the only way how is to crush the can to do so. (It also pushes some water into the can).
Confusing? Just read it again, email me, or maybe just crush another can…
How does the size of a can affect things? How about changing the amount of water in the can? I bet if you thought about it, you could test many different things out here. Just be sure to be extremely safe with this!
I hope you enjoyed this simple experiment. If you have more questions about this, or need tips about science fair ideas around this topic (or others), contact the author.
Steve Davala is a middle school science teacher who likes to write and work with Photoshop. He’s got two kids of his own and subjects them to these science activities as guinea pigs.