MadSci Network: Environment |
The most harmful household chemicals to the ocean are perhaps the bodily wastes that go down the sewer and are dumped into the ocean without being adequately treated. In some places this dumping has produced dead zones on the ocean bottom in which essentially nothing can live. Perhaps the most notorious pollution incident was the dumping of very low concentrations of mercury into one of the bays of the ocean in Japan. It caused some very serious health problems. Mercury itself is not a household chemical, but it has been used to make many. Drano (sodium hypochlorite) is one. Others include the many products based on polyvinyl chloride, often called vinyl. You asked about the experiment in which you added Drano to a salt (sodium chloride) solution and the salt precipitated. [Drano is the correct spelling, not Drain-O.] I suspect your salt solution was much more concentrated than is the ocean. According to the Office of Naval Research the concentration of salt in the ocean is between 3.2 and 3.7 grams per 100 grams of water (see here). You should have no trouble reading this article. The solubility of salt in water is about 36 grams per 100 grams of water. My hypothesis is that your test solution concentration was much closer to 36 grams per 100 grams of water than it was to the concentration in real ocean water. If this were true the addition of some Drano (sodium hypochlorite) might form a precipitate through what is known as the "common ion effect". Discussion of the common ion effect is best left for an AP chemistry course. I really don't think students in grades 4-6 should be handling Drano by themselves - it is dangerous stuff. Please make sure that you have help when doing your experiments!
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