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By Janice VanCleave
Your seventh- and
eighth-grade students are most likely aware of the disastrous consequences
that oil spills can have for the environment. During this Keep America
Beautiful Month, have students try a variation on a method used by pollution-control
experts to clean up a spill.
Materials
Clear, medium-sized
drinking glass
Tap water
6–8 metal washers
Empty prescription container, large enough to hold the washers
Two 24-inch (60-cm) pieces of string
1/4 cup (63 ml) cooking oil
Small bowl
Procedure
1. Fill the glass 3/4 full of water.
2. Place two or three washers in the empty medicine container.
3. Tie the pieces of string together. Tie the other ends of the
strings around the top of the medicine container to form a loop.
4. Place the container, with its two or three washers, in the glass
of water and support it upright with the loop.
5. Continue to add washers until the top of the container sinks
just below the surface of the water. Remove the container and pour out
any water but leave the washers.
6. Pour the oil into the glass, then slowly lower the weighted
container into the glass.
7. Holding the loop, support the container so that its top is just
below the surface of the oil.
8. When the container fills, raise it out of the glass, pour its
contents into the bowl, and observe the liquid.
9. Repeat the procedure until all the oil is removed from the glass.
Results
The first few collections will be pure oil, then a mixture
of oil and water will be collected. Tell students that, fortunately, oil
as a pollutant remains highly visible. It can be collected because it
floats on the water's surface rather than dispersing into the water. Oil
and water cannot mix together into one unified substance. The oil will
eventually separate from the water, even if they are stirred or shaken
together rapidly.
One method of environmental oil retrieval is very similar to this experiment.
An oil drum is weighted so that its top is just beneath the wurvace. The
floating oil then flows into the drum and is pumped out. With this method,
much of the damage that an oil spill can cause will be averted.
Excerpted with permission
of the publisher John Wiley & Sons, Inc., from Janice VanCleave's 202
Oozing, Bubbling, Dripping, and Bouncing Experiments. Copyright ©
1996 by Janice VanCleave.
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