Purpose
To illustrate the presence of atmospheric pressure.

Materials

• Empty pop can (or large metal container with lid)
• Aluminum pie plate
• Hot plate or Bunsen burner

Safety
Wear safety glasses when working with the Bunsen burner

Procedure

1. Add water to an empty pop can until the bottom is covered to a depth of ~1 cm.
2. Using a hot plate heat the can to a point that steam is visible from the opening. A Bunsen burner can be used to heat the can but do not heat the can directly with the flame. Place the can on a wire gauze square that is held by a support ring and stand.
3. Continue heating for a minute, then using beaker tongs, carefully and quickly invert the can in an aluminum pie plate containing water, (or a plastic dish tub half filled with water).

Results
When the can is inverted into the liquid it is crushed.

Follow-up Teaching Notes

• The generation of steam pushes air out of the can.
• Upon inversion in the cold water the steam condenses back to liquid water causing a decrease in pressure relative to its surroundings.
• The atmospheric pressure crushes the can as a result (implosion).

Connections
Atmospheric pressure, changes of state.

Disposal/Clean-up
The pop can may be recycled.

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