Hulk, SMASH!
Crrrunch. It’s the satisfactory sound we all know of crushing a pop can in your fist. All it takes is a little muscle, but can science crush a can on its own? We experimented in class to find out just this!
Amontons’ Law explains that when gases are heated they move around faster. This is best explained by the example of some molecules in a container. Molecules that are heated up will move around faster and as an effect push against the edge of their container with more force or pressure. This increases the volume of the container. Likewise when gases are cooled down they are slower and hit the edges of the container softer and take up less volume. It’s important to note, however, that the molecules themselves are not actually growing in size! They take up more volume only because they require more room to move around more.
In order to produce this phenomenon in science, 3 materials were needed. A can filled with 20 ml of water, a tub full of cold water, and a hot plate. We started off by taking our can with water and placing it on the hot plate. Once the water begins to boil you are ready to see some action. After we took the boiling water in the can and quickly flipped it upside down into the water. Ironically we failed to do this the first time and were met with a very anticlimactic moment. (See the blooper here)
Once you do the procedure the correct way you will be in for a treat. The hot water vapor in the can creates internal pressure that is equal to the external pressure pushing on against the can. Because the can has an opening on the top of the can allowed a few of the molecules to escape the can. When the can is flipped, with the tab under the water, the hot water is cooled instantly by the cold water in the tub. This makes the molecules slow down and the internal pressure drops. The external pressure stays the same but is not met by the same internal pressure. This means that the external pressure crushes the can and it implodes on itself. Our first attempt didn’t end up working that way. Instead of the water becoming cooled in the cold tub, the water became cooled by the atmosphere through the open tab. The tab was facing up towards the air allowing the internal pressure and the external pressure to equalize. Thanks to Amonton and his law, science is capable of recreating that crrrunch!
Want to see the action in real time? Click this link!