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  for Metal Finishing since 1989
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Electroplating for a school science project

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1998

Q. I have always been intrigued by electrochemistry. I am an electronics engineer in communications and have a broad understanding of electronics. In looking for simple experiments I found your site.

I have been using and experimenting with a mixture of baking soda [in bulk on eBay or Amazon [affil links] and distilled water to plate iron with copper. The results are good but I have no idea what is happening chemically.

After plating I end up with blue/green mixture and a milky, heavier substance that is granular. Is this toxic? What gasses are released?

I don't dump it in the drain, but what is the best way to dispose of it? I do siphon off the clear blue/green from the milky and reuse it. It works fine.

I use a voltage, but do I need it? Also I have been able to plate copper onto chrome with good results.

Sorry to sound like an inquisitive kid with a thousand questions, but I live a sheltered life.
Thanks for any help.

Anthony Harris

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Q. Could someone help me out? I did this cool thing in chemistry class. We popped some pennies into a beaker filled with sodium hydroxide and some mossy zinc. Well, they turned silver after a while, and then we took a silver penny and burned it and it turned into gold. Anyway, I need to find a site on the reason why it happened. Could you help me out? Just an example or two of the questions:

"The chemical process you performed in class was called 'plating'. Explain this process as it applied to your experiment."

or …

"What was the alloy produced?"

So, that's about it. I tried using search engines, but they didn't work. Or maybe I'm using them wrong. Anyway, PLEASE HELP!

William J.
1998

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Q. I have a boy that is doing a copper plating experiment. He is doing 2 studies with different volts of batteries. One is a 4.5 volt and the other 6 volt. The solution has vinegar ⇦in bulk on eBay or Amazon [affil links] and salt. There are copper strips added and brass keys are copper plated. When the process is done with the connection by copper wire the 6 volt battery solution turns green? Why is that? It also doesn't seem to copper plate the key evenly. Why is that? He is also supposed to copper plate plastic charms that have graphics on them attached by water downed glue. This does not work. Why not?

Rob Kanallakan
1999

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It is not a good idea to use table salt (sodium chloride) in home experiments like this because of the possibility of releasing chlorine gas if the voltage gets too high. I have generated it with a 12-volt battery charger, but I don't know whether it will be released at 6 volts under different conditions. I'd suggest epsom salts instead. The green color you are seeing, though, is probably copper salts, not chlorine; the green color just means that the solution has copper in it, which it should.

6 volts is probably too high a voltage for your conditions, with the result that the deposit is 'burning' (releasing hydrogen gas and/or chlorine gas instead of just copper ions).

I can't guess why the plastic is not plating; it may not even be conductive.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
1999

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1999

Ted, Like many other letters my child and I are doing a science fair experiment. In spite of your sensible cautions and reluctance your letter 196 is the most informative source we have found yet. My daughter's experiment comes from Electrical Experiments You Can Do ⇦[this on on Amazonaffil links] from the diary of Michael Faraday, by the Thomas Alva Edison Foundation (undated but I have had it for twenty year)s.

It specifies a D cell, vinegar w/salt to the point of saturation a copper strip and a key, all set up and wired in a milk carton bottom. It works too well, the resulting plate is very crumbly and black, gives off smelly gas just as you caution. Simone wants to try plating different metals.

It has however been very educational for her to figure out what is going on by reading about the electrolysis process. Your tips on prep and rinsing are helpful and explanation of what happens the best. She is going to use the hints throughout the various letters and your prep/rinse advice to fine tune it. Keep the site plain. Thanks.

Steven Monrad
- Angelus

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I planning on doing two electro-plating experiments.

1) Copper plating of nickels, dimes, & quarters. Would it be important to use pre 1984 pennies? (Solid copper as opposed to copper plated zinc).

2) Removal of copper plating from the newer pennies to leave just the zinc.

Any help you can give would be greatly appreciated.

P.S. my plan was to use copper sulphate pentachloride

Tom C.
- Atlanta, Georgia
1999

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I have a important test coming up in June for a job in a big company. One of the questions for the oral exam will be to explain in detail the gold electroplating process. HELP? I have looked in every book I could find but nothing. THANKS!

Deb B.
1999

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Deb: Your problem is that the books you could find so far are not the right books. Look at our list of books and see if any are available at your library or by interlibrary loan. A general explanation of plating is in our FAQ on the subject.

What differs in gold plating is that the anodes are not made of gold, but of some inert material like platinized titanium. Thus the gold has to come from additions of plating salts rather than from an equilibrium system of dissolution of the anodes into solution. We'll leave it as an exercise for the reader to figure out why gold plating tanks use these insoluble anodes instead of employing a few dozen gold anodes, each weighing several hundred pounds :-)

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
1999

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Dear finishing.com

For my 7th Form (grade 13) Practical Science Assignment I am required to conduct a set of experiments that investigate a certain topic. For my investigation I wish to investigate Electroplating; I am looking for suggestions on what part of this topic to study, and where to start. Thanks,

Reg Orton
Westlake Boys High School - Auckland, New Zealand
1999

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1999

Dear Reg:

Why not waste treatment/pollution control?

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

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1999

Boy, there are some secretive industries in this world but Electroplating would have to take the cake. Such a simple process and yet surrounded by so much purposeful confusion. If you read between the lines this is because it is a high profitability alchemy process. A dollar of materials is worth hundreds of dollars on the finished product. A good book on the subject is US $450 and more. Not everyone is a lowly serf incapable of handling the materials required to perform the electro and electroless plating process. Smoking and drinking are, in fact, far more dangerous.

This is truly a profit driven industry and not one of free information. Perhaps that will change.

Does anyone else agree?

Siiman Owfski
Sydney, Australia

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1999

A quick apology for some of the questions/comments emanating from Australia. I don't know of any industry not geared to some extent around profit making, more simply put, making a living.

I find finishing dot com is entirely generous in its supply of information. Most of us involved in plating at any level greatly appreciate it (even in Australia!).

Kids will be kids, at least their inquiries show they are attempting homework! However, I have to agree with Ted, most of their info should come from texts (though this site does present a great opportunity to give them a little insight into the practicalities of plating).

On science teachers, I too am a little worried at some of the cavalier attitudes displayed here; I am reminded of my high school chem teacher, who burnt his eyes and suffered extreme jaundice whilst performing a supposedly simple textbook demonstration of polymerisation reaction in hot alkaline conditions. The reaction was only slightly exothermic, wrong concentration and a couple of degrees too high was enough, we all know caustic and eyes don't mix.

Terry Roberts
- Australia

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Q. Finishing a die cast part in gold and silver may be done by using Gold leaf application after silver plating, or is there a "silver leaf" product out there that will work, Both are malleable metals?

S. Murdock
- St. Catharines, Canada
1999

Q. Dear helper; I read through most of the above notes. I must have missed the main answer I was looking for, but did learn a lot (especially about waste concerns w/ plating).

My just-13-year-old spent his birthday last weekend trying the simple copper plating over iron, with pennies in a vinegar/salt solution. It worked, but we had to take the nail out in the bright sun to see copper on it. what I would like him to find is the chemical formula for this, including the chemical name for vinegar if there is one.

Is there a good book that might be in a library for him to review this and include it on the presentation board for his project? Also, since he's 13, this seem like it might be a little bit elementary, any suggestions to make it a little more interesting. Is the bronze plating not recommended? Is there a problem pouring the vinegar/salt solution down the drain? We will discuss some of the waste aspects of plating and will include some on that. thanks for any recommendations.

Kathryn Heires
- omaha, Nebraska
2000

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How come after electroplating the nickel with copper, the copper in the nickel fades and turns into blue green color. I used vinegar with salt 9 volts battery charger.

I put them in separate containers with vinegar using copper as the anode and the nickel as the cathode.

Marc Andres
- Laredo, Texas USA
2001

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I'm not sure I understand you, Marc, but if you don't thoroughly rinse the vinegar off, and dry it, you will still have acid on it that is capable of dissolving copper back into blue-green copper ions.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2001

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2001

Dear Mr. Mooney,

After browsing through your website I stumbled upon an experiment you and another person had found to be quite effective in the electroplating of copper pennies. You used vinegar, sugar, and salt as the electrolytic solution/bath.

I've tried and tested your mixture. I changed it a little however …

I used a six volt battery, the sanded down penny as the anode, and the "bright" penny as the cathode. I filled my transparent tank with 1 gallon of warm water. Then I added 1/8 cup of vinegar, salt and sugar. Once placed in the tank, the cathode immediately began to fizz. After ten minutes, and the re-application of the toothbrush cleaning, my "zinc" penny was quite remarkable. I'm not sure of what was being let out at the cathode, though. Can you please tell me what was being released and how this electroplating process took place even without a SALT of zinc serving as the electrolytic solution? How can this work if the electrolytic bath is not composed of ions of the plating metal?

Any help you can give me would be much appreciated. (The purpose of my doing this is to show how simple household substances can electroplate dull objects). Thank you,

Danielle

Danielle W. [last name deleted for privacy by Editor]

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2001

Hello Danielle, we're happy to hear that the experiment went well for you.

At the anode (the sanded penny) there is a positive charge, i.e., the battery is pulling electrons away. At the cathode (the penny being plated) there is a negative charge, i.e., the battery is supplying electrons.

So, what happens at each end of the cell then is reactions that are consistent with this electron activity.

At the anode, metallic zinc (Zn⁰) is available from the sanded penny. Remove two electrons per atom, pulled away by the battery, and you get Zn⁺⁺ ions of zinc dissolving into the solution. Also available at the anode is water , H⁺₂O^{- -}. Pull electrons away from the oxygen and you get oxygen gas.

At the cathode, electrons are added to the Zn⁺⁺ ions in solution, reducing it to metallic zinc Zn⁰. Also happening though, is electrons are being added to the water, causing the hydrogen in the H⁺₂O^{- -} to be reduced to H⁰, hydrogen gas.

There is a bit more to it, related to the fact that molecules of gases like hydrogen and oxygen usually contain two atoms rather than one, and that, depending on the pH, water may split into hydrogen gas and hydroxide (OH^- )ons rather than hydrogen gas and oxygen gas. But that's the general idea.

By the way, I note that some people mix-and-match pieces of experiments, and that's a good learning experience. Because of that I like to discourage people from using table salt (NaCl) in the experiments, suggesting the use of Epson salts MgSO₄ instead, because we don't want any possibility of chlorine gas Cl^- being released if people get carried away with increasing the voltage, concentration, and acidity.

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

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2001

Mr. Mooney & others,

The "silver plating" mentioned in the first inquiry may well have been the mercury replacement reaction that I, too, did as a kid. Mercuric Nitrate solution, kept in a Skippy peanut butter jar, was quite useful for impressing sixth-grade girls with my "magic". Today, however, mercury is limited from common use by the knowledge that it is very toxic (to humans and in the environment). Mercury-containing hazardous wastes are some of the most worrisome by-products concerning industry today.

Alas, no more slippery, shiny silver pennies! (I'm glad I learned chemistry when I did and lived to talk about it.) My hat is off to you, Mr. Mooney, for your concern about encouraging learning while advising caution and stimulating independent research. Thank you.

John E. Softy
- Mt. Airy, Maryland, USA

Why does the copper leave the pennies and deposit on the iron? I need a simplified reason to explain to my 2nd grader. We're doing Immersion copper plating.

Aileen Paluck
- Sioux Falls, South Dakota
2005

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2005

Start by looking at the acid, Aileen. It consists of 2 kinds of ions paired together, cations and anions. For example, hydrochloric acid is H⁺Cl^-, where you have H⁺ (hydrogen) cations and Cl^- (chlorine) anions paired together in balance, forming HCl.

The Cl^- has a greater affinity for metal than for the hydrogen they were originally bound with. So the acid will dissolve Fe (iron) or Cu (copper), while releasing hydrogen gas, per these reactions:

2H⁺Cl^- + Fe⁰ --> H₂⁰ ^ (hydrogen gas) + Fe⁺⁺Cl₂^- and

2H⁺Cl^- + Cu⁰ --> H₂⁰ ^ (hydrogen gas) + Cu⁺⁺Cl₂^-

But copper is more noble than iron (wants to come out of solution and reform copper metal), so the reaction continues:

Cu⁺⁺Cl₂^- + Fe⁰ --> Fe⁺⁺Cl₂^- + Cu⁰

So what happens is the acid dissolves both copper and the iron, but the iron pairs better, so the Cl pairs with the iron, and the copper has no matching anion to keep it in solution, forcing it to fall out of solution and deposit on the iron article.

As soon as the iron object is lightly covered with copper, the reaction will stop.

Not a great explanation, but it's hard to explain this kind of chemistry to a second grader.

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

I am doing a science fair project and I want to electroplate quarters with copper using copper sulphate. what would I need to mix the copper sulphate with to make the solution? and what kind of volt battery would be best to use?

Mayra
- USA
2005

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2005

Hi,
I would like to post a question to Tom Pullizzi, regarding his post. I was reading through to get some ideas for my school science experiment and I am quite interested in what you said.

He suggested to change someone's project to rinsing? Does rinsing have anything to do with electroplating?

And, are there any other types of experiments to show the concepts of electroplating apart from the plating/coating of metals?

Jenna Mave
- Singapore

An old book of mine tell a VERY simple method of electroplating targeted towards kids if this is what you are talking about. It says to get 2 long wires (doesn't specify) and attached copper end to penny and nickel and the other to the positive terminal (penny) and negative terminal (nickel) of a 6 volt battery. it says to wrap wires around pencil and balance over glass jar with water (water used as the electrolyte). it is supposed to go through the water with the electrical current and copperplate the nickel and be scraped off easily. That the simplest method of electroplating I've come across so far.

Michele
- Venice, Florida
2005

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2005

But does it work, Michele? I doubt it because for the copper to get to the nickel, it has to travel there. And it does not travel as a solid in little flakes; rather it must dissolve in the solution as travel as a copper ion. But how are you going to dissolve copper in water?

If you think it works, please try it and tell us what you find.

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

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WELL I'M LATE IN REGARD TO THE ABOVE QUESTION, but I ALSO TRIED THAT EXPERIMENT AND NO, IT DIDN'T WORK. I TRIED 4 TIMES AND NOTHING BUT DIRTY (BLUE-GRAY) WATER. MAYBE I DIDN'T ALLOW IT ENOUGH TIME (OVERNIGHT YIELDED NOTHING). ANYWAY I'm SORRY TO SAY OUR FASCINATION WITH PLATING HAS NOT ENDED because I AM WORKING ON A SCIENCE PROJECT WHICH IS WHY I'm ON YOUR SITE.

Raquel
- Miami, Florida, US
2005

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No surprise here. Use vinegar instead of water, Raquel, and it will work. Maybe not great, but it will work.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2005

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2006

A great and somewhat easy "experiment," (should be more of a demo for for any classroom presentation) is plating copper (Cu) with zinc (Zn).

Create a zinc salt solution by dissolving Zinc Chloride in distilled water. This breaks the Zinc Chloride into negatively charged zinc ions and positively charged polyatomic chloride ions. Using a 1 1/2 volt D-Cell battery, make a zinc strip your cathode and a copper strip your anode. The copper will soon become plated with with a silvery/grey coat of zinc.

** DO NOT USE MORE THAN 1 1/2 VOLT BATTERY. POTENTIALLY LETHAL CHLORINE GAS COULD BE GENERATED!**

When disposing of the Zinc Chloride solution follow the instructions listed on the appropriate MSDS.

Jonathan Fields
- Mt. Vernon, Georgia

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Q. I want to do an experiment for my 6th grade science fair that measures the effect of increasing voltage on the plating process. I intend to try to plate a dime with copper using a vinegar solution at several different voltages and evaluate the results. Since vinegar is a weak acid, you recommend using a copper cathode and running for several hours before plating to put some copper in solution. My question is: can I pre-prep several batches of the solution with copper cathodes and continue the plating with the dimes a day or two later, or is there some chemical process which will reduce the effectiveness of the solution if I wait?

Conor M [last name deleted for privacy by Editor]
student - Poulsbo, Washington, USA
April 12, 2011

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July 2012

Hi Conor. It should be no problem is you can pour it back into bottles that you can seal. If not, tightly wrapping your bowls with plastic wrap and rubber bands should help. The sharp smell of vinegar is the acetic acid , which evaporates over time if you don't seal it in somehow.

Regards,

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

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Q. I am trying to plate a coin with copper, but there is a problem. At the anode, the copper gets dissolved (which is normal).
But at the cathode, there are bubbles forming and the coin gets plated with copper ... the coin doesn't get plated nicely.
The electrolyte I'm using is dilute copper sulphate.
Please help

ashwin p [last name deleted for privacy by Editor]
- sb, selangor, malaysia
July 28, 2012

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Q. Sir,
I need your help .
I'm in trouble; my holidays are going to be finished and I have less time, so I have got a holiday homework in science to make something by electroplating. Sir, can you give me a model description?
Please sir, reply to me soon.

Aman [last name deleted for privacy by Editor]
- Etawah, Uttar Pradesh, India
January 9, 2013

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