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Science project: Turning pennies gold color (actually brass)


Q. My son is in the 8th grade and wants to do electroplating for his science project. A few years back he saw a project where pennies where electroplated to look gold. After each demonstration the kid handed out the shiny gold pennies. My son kept his for years. How is this done? Can you help me find a book or other resources that will help with a project like this? Any suggestions will be greatly appreciated.

Cheri Kozlowski
- Longwood, Florida


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Q. Hi, my name is Jonathan. In 7th grade, I did the experiment where you turn pennies into gold or gold plated. I have always wanted to do this experiment, but I never new the materials that were needed to do it. If you could, tell me the materials that is needed and maybe a site that I might be able to get them at.

Thank-You

Jonathan A.deleted
student - Omaha, Nebraska, USA



A. Place about 5 g of Zn dust in an evaporating dish. Fill the dish one-third full of NaOH. Heat to near boiling. Clean a penny with steel wool [linked by editor to product info at Rockler] and place in the dish. Heat 3-4 minutes until reaction is complete. Wash the penny under running water and gently blot dry. The penny looks silver - it is zinc coated. Hold the penny in a burner flame (use tongs) long enough for the color to change. The penny looks Gold - it is brass coated. Brass is 60 to 82 % Cu and 18 to 40 % Zn.

Kulisia deleted
- London, Ont, Canada


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A. Umm also for the Zinc you could use 3 - 4 nails, and for the NaOH use Dranoamazoninfo (powdered)

Alex Jalaff
- Fenton, Missouri


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!  Thanks, Kulisia, thanks Alex. People need to know, though, that NaOH or Drano is quite dangerous cold and even more so when near boiling hot. Maybe with gogglesamazoninfo and gloves this experiment might be appropriate for high schoolers under careful supervision, but certainly not grade schoolers.

For a simple and safe plating experiment, see our FAQ for zinc electroplating. I'm not sure if this will diffuse with the copper of the penny when heated and produce the gold-colored brass alloy -- but finding out what will happen is what experiments are for :-)

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

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Q. I need help to find a project for science fair. Fair and understanding project. High school science fair topic only. Thanks!

Shirley Ydeleted
- St. Paul, Minnesota


 

A. Boil 20 ml caustic soda solution (drain cleaner works). Add 1 g zinc filings. Place a clean penny in the mixture. Remove the penny after about 10 mins. It will be silver (I believe plated with zinc). Heat the penny gently with a propane torch. It will turn gold. The zinc and underlying copper combine to form bronze. Needs careful supervision. We prepared a health and safety plan before we started and made it an integral part of the project.

Michael Longland
- Toronto, Ontario, Canada



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Q. I am a high school chemistry teacher. Many years ago I worked at a plating house and have a vague recollection of the art of electroplating. We have a nifty little lab in the school where the students do zinc immersion plating on a penny (heated zinc chloride/Zn solution). After the penny is removed from the bath, the students "wave" the penny over a flame and witness the mixing of the atoms as evidenced by the appearance of the characteristic brass color. Only problem is that some students get fabulous results while others are disappointed. We have tried old pennies and new pennies and consistency is elusive. What I remember most about plating is that surface prep is everything.

Can anyone suggest a pretreatment routine that will improve my product to scrap ratio for these students. I recall that cleaners, etchants and rinses are routine chemicals. I do not need to pass any QA specs so exotic additives etc. are not necessary.

Thank you ever so much. The kids love! the lab but, as you can imagine, some feel it is more magic than electrons because of the unpredictable results.

Mindy Lekberg
- Chelmsford, Massachusetts



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March 21, 2008

Q. I found a gold looking penny...not sure if it is real gold. Can you tell me if there is any significant value to this coin?

Cale Werner
- Bath, Pennsylvania, USA


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Q. I found a penny that is gold-ish in color and dated 2002, I scratched one side to see if it was paint, but found nothing underneath. What do I likely have? =>

Mike Harper
- Louisville, Kentucky, USA

gold penny

March 26 2008

Hi Cale; hi Mike. You've just read about one cheap way that students make gold looking pennies; and countless thousands of pennies have also been gold electroplated with a worthless thickness of gold as giveaways. While a discarded lottery ticket could be the grand jackpot winner, and a gold penny could be solid gold, the chances of either are essentially zero. Gold is more than twice as heavy as copper, so if the penny doesn't feel outrageously heavy, sorry, it's not gold.

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


January 29, 2013

Q. I have a 1984 penny that looks like gold but I'm sure it's probably not but I'm no expert on coins. It's very shiny and looks new and is very light. Any idea ?

Christinadeleted
- Glendale, Arizona, US

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