Unexpected Implosion
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What Is an Implosion?
We are all familiar with the term "explosion." An implosion is its opposite in terms of the direction of the blast. During an implosion, the shockwave spreads inward, unlike in the case of an explosion. This phenomenon involves the sudden collapse of matter within a confined space:
An implosion occurs particularly when the walls of a container collapse inward due to low internal pressure.
Implosions can be observed, for example, when a vacuum light bulb or cathode-ray tube breaks. In this experiment, we will demonstrate a sudden implosion using a soda can.
Let’s Get Started!
You will need a metal soda can:
Pour a small amount of water into the empty can (to a height of about 1 cm or approximately 0.4 in.). Then, heat the open can with water until it boils. You can use a spirit burner, a gas burner, or a regular stove.
Warning: Exercise caution, as this experiment involves high temperatures. Burns from boiling water or hot steam can be severe and slow to heal! The author assumes no responsibility for any damage or injury that may occur. You proceed at your own risk!
When the water reaches 100°C (212°F) at sea level, it will start to boil. An important detail is that water vapor is heavier than air, which means it displaces the air inside the can, leaving only hot steam inside.
Once the water in the can starts to boil, allow it to heat for a few more minutes. In the meantime, prepare a bowl of cold water. The water can contain ice cubes, as it should be as cold as possible. Then, using protective gloves (I used regular work gloves), grab the can, quickly turn it upside down, and immerse it in the cold water. The can is instantly crushed—this is a genuine implosion. You can see the entire experiment in my video below:
You can clearly hear the cracking sound of the can being crushed by external pressure. Below is a photo of the can after the implosion, compared to a regular can.
The explanation for this implosion is simple. During boiling, hot steam accumulates inside the can, displacing the air through the opening. When the steam is rapidly cooled in the water, it condenses into liquid. Since the can contained almost nothing but steam, a near-vacuum is created. The pressure drops so much that the water being sucked into the can cannot equalize the pressure quickly enough, and the can is crushed by the surrounding atmospheric pressure.
Enjoy and have fun experimenting! :)
Further readings:
- Moholkar V.S., Pandit A.B., Bubble Behavior in Hydrodynamic Cavitation: Effect of Turbulence, AIChe Journal, 1997, 43(6), pp. 1641–1648
- Ozonek J., Application of Hydrodynamic Cavitation in Environmental Engineering, CRC Press, 2012, pp. 43
Marek Ples