There are many ways to crush a can. You can twist it in your hand, step on it with your foot, and even smash it against your forehead (ouch!).
What if I tell you that you can crush a can with air?
In this air pressure experiment, I will show you how we can crush an empty soda can using nothing else but a heat source and water. Your kids will love the can implode like magic when it touches the ice water.
** This experiment is awesome for younger kids to watch, but not to do. Please use caution while handling the hot can and ask your kids to step back while you demonstrate.
How to Crush a Can with Air Pressure
- Stove or hot plate
1. Rinse the inside of the cans.
2. Fill the bowl with water. Add ice.
3. Add about a tablespoon of water to the can.
4. Place the can on the stovetop or hot plate until the water inside boils. You can hear the bubbling water and see the steam rising from the can.
5. Use the tongs to get a good grip near the bottom of the can (with your palm facing up). As fast as you can (but safety first!), move the can to the bowl and turn it upside down into the cold water.
6. Try and contain your surprise as you hear the loud “pop” and see the can crushed instantly!
Did you jump when the can imploded? I knew the “pop” was coming but I jumped anyway … all 3 times we did the experiment.
The first time we did this can crusher experiment, we did a couple of things wrong and the can did not implode. Here are some learnings from our mistakes:
- Make sure you boil the water inside the can. You might see steam come out of the opening but also listen for the bubbling of boiling water.
- When you plunge the soda can upside down into the cold water, make sure you are holding the can straight up and down instead of slightly sideways. You don’t want cold water to enter the can.
- Do place the can inside the cold water immediately after removing it from the heat source. Waiting too long would allow the hot water vapor to escape and cold air to get inside.
Science Behind the Can Crush Experiment
This science experiment is great to show your kids how powerful air can be. Since we can’t see air, we often forget about it. But air pressure can actually apply a lot of force on objects (and us!).
When the water inside the can boils, the hot water vapor pushes out the cool air inside the can. The water vapor also exerts pressure on the inside walls of the can, pushing it outward. At this point the air pressure inside the can is equal to the outside of the can.
When you turn the can upside down and plunge it into cold water, you suddenly cooled the can. The change in temperature caused the water vapor in the can to condense into a few drops of liquid, which take up much less space.
The pressure inside the can is much less than the outside of the can. With the opening of the can in the water, no outside air can get in. The result is the difference in air pressure between the inside and outside of the can was great enough to crush it.
When you lift the crushed can, you probably notice that there is water inside the can. Similar to what we saw in the rising water experiment, with the pressure outside the can much greater than the pressure inside, the pressure actually pushes the ice water up and into the can.
For more air pressure fun, check out: