Collapsing can or can crusher experiment is a demonstration of an

aluminum Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

can being crushed by

atmospheric pressure Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1,013. ...

. Due to the low

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and eve ...

inside a can as compared to the pressure outside, the pressure outside exerts a force on the can causing the can to collapse.

Explanation

The demonstration starts with boiling water inside the can. As the water is boiled,

water vapor Water vapor, water vapour, or aqueous vapor is the gaseous phase of Properties of water, water. It is one Phase (matter), state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from th ...

is created and fills the space inside the can which then pushes the air out. H₂O → H₂O Then, inverting a water vapor-filled can into a water bath causes the water vapor to rapidly condense back to liquid water. The

condensation Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor ...

of water reduces pressure inside the can, so the higher pressure outside the can makes the can collapse. H₂O → H₂O

Limitation

Since the can is open when immersed, this demonstration only works with aluminum cans. Aluminum cools quickly when immersed, causing almost instantaneous condensation of the steam, leading the weak aluminum to collapse. With steel cans the water in the cooling bath condenses the interior steam by contact through the opening in the can. Then the cooling water is drawn inside the can by the reduced pressure preventing the collapse of the can. The steam condenses before the steel cools. A variation where the opening in the can is sealed air-tight can make even a strong a

steel drum The steelpan (also known as a pan or steel drum) is a musical instrument originating in Trinidad and Tobago from Afro-Trinidadians. Steelpan musicians are called pannists. In 1992, the steelpan was declared Trinidad and Tobago’s national in ...

collapse. After the water inside the drum boils and forces the air out, the opening is sealed air tight. When the steam condenses the can, or drum, will be crushed by the pressure differential between the internal partial pressure of water, and the external atmosphere.

Alternatives

Addition of

sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula . It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive base (chemistry), ...

to a can filled with

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

can produce a similar result.Archived a
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Gallery

File:Can_crusher.webm, A video of collapsing can experiment File:Can_crusher_2.webm, A video of collapsing can experiment

References

{{commons category, Can crusher

External links

Can Crush Demonstration
Physics education Chemistry classroom experiments Articles containing video clips Atmospheric pressure