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Hands-on
Lab
Objectives
Students will:
- construct a testing apparatus for rubber bands
- use rubber bands to determine the effects of
ozone on rubber
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Materials
rubber bands
wire hangers
- or -
wooden blocks
thumb tacks
length of wire
small hook |
Background
| High concentrations of ground level
ozone in the ambient air that we breathe can present many
problems. Because ozone molecules are highly reactive, they have
an effect on practically every material they contact, whether it be lung
tissue, crops or other vegetation, rubber, plastics, paints, etc. |
Procedure
Wire Hanger Apparatus
1. Bend the wire hanger and create more of an oval shape. The oval
should be large enough so that when the rubber bands are stretched over the hanger, they are tight.
- or -
Wooden Block Apparatus
1. Obtain or cut a wooden block about 8 inches long and about 3
inches wide. Screw the small hook into the top edge of the block
of wood. Place two thumb tacks at least 5 inches apart and secure
into wood. Stretch the rubber band around the thumb tacks.
Attach the length of wire to the small hook.
2. Hang the hanger or wooden block outdoors in a shady place so it's out of
direct sun for two weeks.
3. After two weeks, inspect the rubber bands. Do they look the way
they did before, or are they cracked? Check with the magnifying glass
if necessary. Touch the rubber bands. Do they feel the way they did before, or are they
hard? If they look and feel the way they did before, then the air is quite
clean. If they look cracked and feel hard, then the air is polluted.
4. If no damage is observed, leave rubber bands out for two more weeks
and inspect again. In certain areas, ozone damage may not be
observed until Ozone Season (May - September).
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This lesson was adapted from the University
Corporation for Atmospheric Research, Cycles of the Earth and Atmosphere
module and the Environmental Resource Guide from the Air and Waste Management
Association.
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