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2B30.15 - Pop Can Collapse

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​2B30.15 - Pop Can Collapse

Title2B30.15 - Pop Can Collapse

Demonstrate that the pressure of steam is much less than air at room temperature.

Assembly Instructions
The wire mesh should be placed atop the ring stand and placed over the Bunsen burner.  Be sure to fill the dish with water at least one inch deep so that when the pop can is inverted, there is enough water to cover the hole in the can.  A beaker of water is also included to fill approximately 1/8" of water in the pop can before it is placed onto the wire mesh.  Make sure to remind the lecturer to allow for the interior of the can to be fully saturated with steam before inversion takes place.
Setup Time10
Operation Time5
Preview Time5
Operation Instructions

Overview:  Use only about 1/8 inch of water in can. Make sure that the interior of the can is fully saturated with steam before inverting. Practice the inversion move with cool empty can.  The sudden condensation of the steam in the can will cause the can to collapse abruptly and violently as the atmospheric pressure is much greater than the air pressure in the can.

Operation Steps:
1.    Pour a small amount of water in the can (~1/8” deep)

2.    Turn on the heat source (Bunsen burner), and place the can on the flame
3.    Allow can to heat for a long time (~3-5 minutes)
4.    When the can is producing a lot of steam, grasp it with the tongs and quickly invert it and dunk it in water.
5.    The can should instantly collapse.
Demo on Dime
PIRA 200Yes
Export Instructions (if different)
HazardsCaution - Open Flames

Analysis: ​A difference in air pressure inside and outside the can causes a dramatic collapse.  When the can is inverted and dipped in water, the hot steam cools and condenses back into water.  As the temperature goes down quickly, so too does the pressure.  Since there is no open path between the air inside the can and outside the can (the opening is now underwater), the can is not strong enough to support the difference in pressure, therefore it collapses.  This vividly shows how powerful a force difference can be.​

Category2 Fluid Mechanics
Subcategory2B - Statics of Fluids
Keywordsinvert pop can, cold water, atmospheric pressure, atmosphere, collapse, steam
Construction Information
bunsen burner
ring stand
wire mesh - flame disperser
pop can
bowl glass large
tongs metal 12 inches
beaker 500 mL/16 0z plastic