Letter 17830

New Pennies and Several Acids; an Observation  

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A more appropriate title would be "What Happens When Metal Finishing Personnel Have Too Much Time on Their Hands". Last Thursday night before heading home, I dropped a new penny into a beaker containing 50 mls of 64% hydrochloric acid. Eighteen hours later, analysis of the HCl solution revealed that the penny had lost 2 milligrams of copper. I then dropped a second new penny into 50 mls of 5% acetic acid (vinegar) containing 0.5 grams NaCl (table salt). I heated the solution to 155 degrees F, then allowed it to cool. Analysis of the solution (two hours later) revealed that the penny had lost 1.65 grams of copper. A third new penny was submersed into 50 mls of 50% sulfuric acid solution containing 5 mls of 35% hydrogen peroxide solution. Eight hours later, the penny did not exist. Yet a fourth new penny was submersed into 50 mls of 50% nitric acid. Eighty seconds later the penny did not exist. Having spent my entire paycheck, I performed no further experiments! .

Randy Fowler Metal Surface Technologies, LLC   Cleveland, TN, USA

One experiment is worth more than a thousand guesses or opinions, Randy. You've certainly provided a lot of data for both students and professionals. Thanks!

Ted Mooney, P.E.  finishing.com Brick, New Jersey

I'm impressed by your tenacity and compliment you on your observational skills. Having spent your total wage packet on the tests, one must admire your dedication. However, we now must face the cruel fact that we are all underpaid in this industry! Perhaps our customers should be taught of our total dedication to their quests to make as much money as they can, often at our expense!

Trevor Crichton R&D practical scientist - UK

Hi Ted and Trevor,

Thank you both for your responses. Actually, the penny submersed into vinegar solution lost 1.65 MILIGRAMS of copper, not 1.65 grams. My mistake. You're correct, Trevor, in your assesment of metal finishing folks. We do tend to be passionate about our profession, regardless of our pay scale. Trevor, what exactly is your line of work? You seem to have a wealth of diverse information, whatever the subject. Just curious.

Randy Fowler Metal Surface Technologies, LLC   Cleveland, TN, USA

Randy,

Just to put your mind at rest, for the past 15 years or so I have worked for an American company in one of their British research facilities. For obvious reasons I cannot talk too much about this, but my speciality is metal finishing and surface engineering. I also have a strong interest in environmental, health and safety issues. All in all I have about 25 years experience in chemical and metallurgical research in both contract and industrial R&D as well as some years in academia. I also have about 5 years experience in manufacturing (poacher turned game keeper, or perhaps vice versa!). Hope this answers your query.

Trevor Crichton R&D practical scientist - UK

Randy,

I have learned better than to differ with you and in the process have learned to respect your knowledge. (HCL and the VI valance of chrome stuff, gosh was I wrong!) With the new penny's were you looking at the rate of copper dissolving? I only point out that our new Yankee penny is zinc core and copper clad. Also I read Trevor's reply with interest.

Jon Quirt
- Fridley, MN

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