#1245. The pressure of invisible air

Science, level: Elementary
Posted Thu Aug 12 11:02:23 PDT 1999 by Patrick Fureman (patfury@hotmail.com).
Dallastown Area School District, Dallastown, PA, USA
Materials Required: Bunson burner(heat source),Large metal container(cleaned)with screw top, water, ice, large container
Activity Time: 45 min. - 1 hour
Concepts Taught: Air takes up space and has pressure

1. Place a small amount of water into the metal container(with th lid off).
2. Boil the water until steam is leaving the metal container.
3. Turn off the heat source.
4. Carefully screw the lid onto the hot metal container tightly.
5. Using OVEN MITTS, remove the metal container and place it into a large container of ice water.
6. The metal container will be crushed by the outside air pressure.
EXPLANATION:
The boiling of water changes the water from a liguid to a gas. As the gas leaves the container,
you shut off the heat source and screw the lid on the container. This prevents air from returning
into the metal container and a vaccuum is formed. By placing the container into ice water you speed
up the cooling process of condensation, thus turning more of the inside air back into water and
increasing the size of the vaccuum that exists. This speeds up the crushing process. THE VACCUUM MUST
BE FILLED BY THE METAL CONTAINER!!