Metal Reactions in Water
Date: December 2007
My 7th grade daughter is doing a project on 5 metals and
how do they react in salt water, fresh water (lake), and tap water
(well). We noticed the aluminum, brass, and stainless steel did not
react to any of the waters. The plain steel started to actually
corrode and grow stuff on it, in all 3 waters. The copper, which is
neat, turned green and turned the water green in the salt water
only. All I can figure out and find on the net is this - fresh water
and well water is mostly deionized and has a minimum of ions. Salt
water has a high amount of ions, and the ions start to interact with
the salt particles causing a reaction. Is this correct or did I come
to a wrong conclusion? I still do not have much more of a conclusion
other than that. Can anyone explain to me WHY copper does this, and
why the others do not?
The right path to finding the answer of why copper turns the salt
water green is knowing in which specific ions salt water is rich.
The answer is that salt water is rich in sodium chloride ions.
Specifically chloride ions will form copper chloride, which will
turn the water green. Copper sulfate is also another common water-soluble
copper salt--this would turn water brilliant blue. The other metals either
do not form water soluble salts, or do not form salts that are highly
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Update: June 2012