Use air to crush a can in this science experiment. We are so accustomed to the pressure of the air around us that we don't even notice it. However, air pressure is great enough to crush a soda can when you know how to do it. This classic experiment is called the collapsing can.
- Empty Soda Cans - Hot Plate or Electric Kitchen Stovetop - Water - Large Bowl - Ice - Tongs
Watch Video: Collapsing Can Experiment
Process Collapsing Can Experiment:
1) Fill your large bowl with some cold tap water. Add some ice and let the ice melt. This will make the water nice and cold.
2) Get out your empty soda cans and add in tablespoon of water to each. This should be enough to just barely cover the bottom of the cans when you look inside.
3) Turn on your hot plate or electric stove-top burner to high (be careful not to burn yourself. Use oven mitts or gloves).
3) Place one can on the hot plate or stove-top and heat the can until the water begins to boil. You will be able to tell once the water boils because a cloud of condensed vapor will steam up from the opening in the can. You can also hear the boil and look inside and see the bubbles. Don't use your bare hands to touch the hot can - that will hurt!
4) Let the water boil inside the can for 30-40 seconds.
5) Then grasp the can using the tongs. Very quickly turn the can upside down and shove it deep into the bowl of cold water. Try to shove the can all the way into the cold water quickly . The can will collapse almost instantly.
6) Crush some more cans!
The Science Behind The Collapsing Can: Why did the can collapse? We heated the can on the burner and made the water inside boil. As we did this the water vapor from the boil forced air out of the can. Once the can was filled with hot water vapor, it was cooled quickly by turning it upside down and submerging it in the cold water. The cooling process caused the water vapor inside the can to condense. Which in turn created a partial vacuum. The partial vacuum generated low pressure inside the can (lower than the 14.7 pounds per square inch that surrounds us). Then the higher air pressure of 14.7 pounds per square inch outside the can crushed it.
The can was crushed / collapses when the air pressure outside became greater than the pressure inside. That pressure difference was greater than the can was able to withstand. The same thing happens when you collapse an aluminum can with your hand. Squeezing the sides of the can makes the pressure outside greater than the pressure inside. If you squeeze really har the can is crushed. Normally, air pressure inside a open can equals the pressure outside. But in this demonstration, all of the air was foreced out of the can by water vapor. Once the water vapor cooled and condensed, the air pressure inside the can became much less than the air pressure outside. Next the greater pressure outside the can crushed it. Now go and make some collapsing cans with your friends!