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Frustrated over a Simple 4th Grade Experiment

(-----) January 21, 2008

Hello, I was wondering if you could assist me with a question. I have been desperately trying to help my 4th grader with a simple experiment we found in a book for children. It simply says to put a copper strip into salty water along with a chromium key and attach both to a 4.5V battery. When cannot get anything to happen. Can you tell me what I may be doing wrong? The first thing that I am thinking may be wrong is that I really don't know where to find a pure chrominum key. We went to Wal-mart and got a key and I am sure that it is some sort of alloy. Please help me get the tears out of my little one's eyes ! THANKS ! Joshua P. (4th Grader) and Mom (Monica P.)

Monica P.
Student - Cordova, Tn

January 22, 2008

Please name the book, Monica, because this reference is a bit crazy. First, keys are never made of chromium, although they might have a thin plating of nickel and then chromium. But secondly, you won't be able to plate the copper onto the chromium, nor the chromium onto the copper. Thirdly, 4.5 volts is way too much. Fourthly, the experiment will be far more practical if you use vinegar with a little salt in it rather than salt water.

Plate the copper onto a quarter rather than onto a key and your son will be happy. Please see our FAQ: "Plating - How It Works" to see how to plate copper onto the coin. Good luck.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

January 24, 2008

Correct that the keys are not chromium. Actually they are generally brass with a nickel plate, no chromium.

Gene Packman
process supplier - Great Neck, New York

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