The Department of Chemistry at the University of Illinois
The Chemistry learning center
Why does a Coke can filled with steam collapse in cold water?
Coke cans containing a small quantity of water are heated until the water boils. Steam (gaseous water), fills the can and pushes the air out the hole in the tops.
the can has filled with steam, it is quickly immersed in a container
of ice water.
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The steam is
cooled in the ice water and condenses to a small quantity of liquid
water. Condensation of steam to liquid water creates a vacuum inside
the can. Atmospheric pressure outside the can is around 760 mm Hg,
while pressure inside the can is much less. The can collapses because
of the pressure difference.