Science fair project: Electroplating with copper

A. Hi Andre. Although I find it hard to believe that neither your town nor school library has an electroplating text or even an encyclopedia with a worthwhile entry under 'electroplating', you came to the right place. See our "How Electroplating Works" FAQ. We also have thousands of electroplating threads for as deep a discussion as you wish.

You are correct that chromium would be a bad choice from safety and environmental aspects, but zinc plating is not necessarily cyanide based, and is a good choice.

We suggest that you either copper plate or zinc plate your item, using copper wire as the source of copper or sanded down pennies or a zinc boat anode as the source of zinc, and with vinegar ⇦in bulk on eBay or Amazon [affil links] as the electrolyte, and with the following additives:

• some epsom salts to aid conductivity
• a little sugar as a brightening agent
• a drop of dishwashing liquid as a wetting agent

A 1-1/2 volt D-cell flashlight battery will supply enough voltage and current. Good luck.

A. Your 9th grade science project should be an attempt to safely demonstrate principles, rather than to actually produce electroplating suitable for industrial use, so I think you should plate onto coins: for good contrast, zinc plate onto copper coins like pennies, or copper plate onto dimes and quarters.

A drop of dishwashing liquid will do no harm. Whether it will do any actual good in a 9th grade experiment is questionable: it just makes the water wetter. The cathode (the thing you are plating onto) must be absolutely clean because you are trying to build onto the crystal structure of the metal, and even a fingerprint will prevent that; the cleanliness of the anode (the material dissolving into solution) is much less critical.

I do not think you should do nickel plating, both because some people are allergic to nickel (nickel itch) and because any solution that contains chlorides (as nickel chloride does) can accidentally produce chlorine gas at higher voltages under unusual circumstances. This is why we suggest using epsom salt (magnesium sulphate) rather than table salt (sodium chloride).

THANKS a lot for all your help and advice. I'll do the experiment you suggested.

A. Greetings Andre, I must really be getting old :-) -- I remember doing this same type of project for my 8th grade science project.

If I remember correctly though, since I've always been around plating I had the "commercial" grade copper plating bath and I copper plated a nail. The feeling I got when it worked was amazing, a whole new world opened up to me when that happened and science became a very important part of my life. Once you plate that first object don't be surprised if you get this unstoppable urge to dive deeper into the whole realm of metal finishing, it's a huge world and an extremely enjoyable one to be associated with. Good Luck to you young man, and hope to see you on the plating trails later in life (you never know).

A. It might plate out almost as fast as it dissolved, so it might not help much. Further, you would probably lose some of the acidity, and that's a pretty precious commodity when you are deliberately using a very weak acid for safety reasons.

I'd let it sit and dissolve a while, but I'd agree with you that the dissolved zinc probably doesn't approach 100 grams per liter.

A. The electroplating is awfully thin, probably just a few millionths of an inch. Between wearing off and difusing into the copper it may appear to vanish. I think you are going to have a very difficult time weighing such a thin coating. But if you electroplate for several hours or overnight, instead of for a few minutes, you might have a fighting chance. If you can get a science teacher to help you, you could use dilute sulfuric acid instead of vinegar and you could plate much faster, but it is too dangerous to do without training and protective gear.

Voltage is necessary to make the current flow, but is not a primary variable. A more interesting experiment might be the effect of current and time, since you would be working towards proving or disproving Faraday's Law of Electrolysis -- a very interesting and really important law which says that 96,485 coulombs (ampere-seconds) will deposit one gram equivalent of metal.

A. The object which you wish to plate onto is connected to the negative terminal of the battery. If you are doing this as a chemistry lesson rather than as play, you need to understand why, Dima, and it is explained in the FAQ you were looking at.

The solution is apparently far more corrosive with salt in it than with just vinegar in it.

Thanks a lot. My science project was a complete success, and I got an award.

!! Way to go, Dima. We're happy for you!

A. Hi, Sam. The green color was apparently dissolved copper from the wire. If a copper wire is in the solution and attached to the positive pole of the battery, yet it will dissolve away quickly. As for the 'black coating though, are you sure the voltage was never above 1-1/2 volts?

Regards,

A. Hi, Tony

1 & 2). Makes no difference. Just stir it a bit.

3). Our "How Electroplating Works FAQ" suggests plating a penny with zinc or a coin or brass key with copper. Copper wire is the best source of copper.

4). The anode is the positive pole in the circuit, and often it is made of the material that you wish to plate with, and supplies the metal by dissolving into the solution.

5. You'll see something happen in a few minutes with the zinc plating, it may take a half hour to see the copper plating start working.

6. You can use table salt.

Good luck and Regards,

A. Hi Amit. As you read here, electroplating a copper or brass coin or other small object with zinc is quite easy and inexpensive.

Regards,

A. Hi Bob. It's fine to ask for answers, but if you don't understand the questions you're asking, it's vital to tell your teacher, so you make sure you understand what the exercise is about. How could you tell a right answer from a wrong answer if you don't know what the question means? Anyway ...

Imagine taking a single piece of metal and putting it into a liquid and observing that not much happens. Then you take a pair of tin snips and cut that piece of metal in half ... would we now expect something to happen between the two halves? That would make little sense. So if you put two pieces of the same metal into the solution you'll get no net reaction between them.

However, if you connect one of the pieces to the positive pole of a battery, and the other to the negative pole of the battery, the battery is going to try to pull electrons from the piece connected to the positive pole and pump them over to the piece connected to the negative pole. This will leave you with a shortage of electrons on the one, and an excess on the other. The metal atoms that are short of electrons will become positively charged ions and dissolve into the solution and be attracted to migrate over to the negative pole. When those metal ions reach the negative pole, their electrons will rejoin them and they will become atoms again.

So what will have happened, on net, is that some atoms will move from the positively charged pole to the negatively charged pole in two "halves": their electrons getting there through the copper wire and the battery, and their positively charged ions getting there by floating through the liquid. And the positively charged piece of metal (the anode) will melt away, while the negatively charged piece of metal (the cathode) grows thicker as additional metal plates out onto it. Good luck.

Regards,

A. As described by Ted, not much would happen if you had used good distilled water as your liquid.
I think that you would be more probable to generate H gas at one pole and O gas at the other.
Now add a bit of salt or acid to the water and it becomes greatly more conductive. If your metal is copper, a bit of copper sulphate and sulfuric acid will give you a poor man's electroplating cell.
Change the negative metal to a clean piece of steel and you set up is no longer net 0 but is an effective demonstration of copper plating.
Vinegar (acetic acid ⇦ this on eBay or Amazon [affil links] ) would be a bit safer but less effective.

A. Hi Bob. Are you seeing zinc plate out onto the copper all by itself or are you just predicting that it will happen? Unless your zinc nitrate solution is awfully strong, or unless you apply voltage to make it happen, I don't think it will happen. I encourage students to actually do their experiment before seeking explanations for a number of reasons; but one of the reasons is that you can find yourself trying to explain why things happen when, actually, they don't -- and soon you're hopelessly confused :-)

We can talk about Faraday's Law, and standard potentials, and the Nernst equation, all of which have great bearing on your experiment. But before we do, do yourself the favor of carefully documenting the setup, and the observations and facts that you actually record ... then the reason things happen the way they do will be easily explicable. You are not correct that the EMF is zero, unless you have applied electricity long enough to have caused a heavy non-porous layer of zinc plating to be deposited on the copper. I think you may confuse yourself by accepting that as a given or adopting that terminology.

If you have already applied electricity long enough that you now have two zinc electrodes with no copper exposed, and you are continuing to apply electricity and continuing to dissolve zinc from the anode and plating it out on the cathode, then we can talk about Faraday's Law and its bearing on the situation. But after two postings, what you have actually done and what you have actually observed or measured are still big question marks for me. Good luck.

Regards,

A. Hi. Re:"form a complete layer of copper". Is this a typo -- did you mean "form a complete layer of zinc ON the copper"?

While Faraday's Law remains fact, it doesn't actually say that you will deposit x number of grams of Zinc ... it says that you will reduce x number of equivalent weights of something at the cathode and oxidize x number of equivalent weights of something at the anode. Yes, that "something" may include hydrogen at the cathode and oxygen at the anode. The electrons you remove from the anode and pump over to the cathode will cause something to happen. Most of what will happen will usually be movement of zinc from the anode to the cathode, and platers sometimes talk about cathode efficiency and anode efficiency. If 80% of the electricity used causes deposition of zinc and 20% causes liberation of hydrogen from the water, we say the cathode efficiency is 80%. Similarly, the process at the anode will operate at some efficiency depending on concentration, amperage, voltage, temperature, pH, etc.

It is possible for the cathode efficiency to be different than the anode efficiency, such that you deposit more or less zinc than you dissolve from the anode. But this cannot continue for long because the zinc doesn't disappear; rather, the concentration of the solution increases or decreases accordingly. This is one reason platers must hold tight limits on process variables -- so the cathode and anode efficiency match up and the solution concentration stays in equilibrium.

Regards,

A. Hi Mark. In the Hull Cell you will encounter a low resistance in the wiring, and a low resistance in the anode and cathode, but a high resistance across the liquid (the plating solution) -- so I don't think that particular experiment will work well because the low resistance of the anode will be masked by the high resistance of the solution.

Very few kids have access to a Hull Cell, which is a nice professional tool, so why not use it for the purpose that it was intended, and demonstrate what it can tell you (that the plating comes out differently where the anode is very close to the cathode than where it is far away from the cathode), how it tells you that, why it matters, etc.?

Regards,

A. You could try this: make an acid copper bath, and plate panels in your cell with varying amounts of molasses added. (Yes, molasses from the grocery store) You should see a substantial difference in the appearance and quality of the plate.

Usually available on eBay;

sometimes on
AbeBooks or Amazon

(affil links)
free pdf is currently available from academia.edu

A. Hi Mark. Very few American high schoolers experiment with electrochemistry as deeply as you have already done in middle school. Congratulations to you, your dad, and your instructors :-)

Your copper sulphate concentration is low if anything. Please see the copper sulphate plating bath formulations in the Metal Finishing Guidebook.
Real copper sulphate plating baths involve sulfuric acid as well as the copper sulphate, and the lack of it is one possible source of your difficulties. But another is that copper sulphate based plating baths cannot deposit directly on steel. Do you possibly have access to brass Hull Cell panels? Good luck.

My first field trip as a fresh engineer nearly 50 years ago was to a plating shop in your general area with a name remarkably similar to yours -- any relation?

Regards,

A. Good day Mark.

It is very refreshing to read about your project.
I learned about electroplating at your age also. Ted has given you the information of the basic solution composition of the acid copper bath.
I do not know how much info/experience that you, or your father have regarding plating.
I would like to add that you should use phosphorised copper anode material (if you are using brighteners) along with vigorous solution agitation in the hull cell. Are you making your solution with de-ionized/distilled water? Try to determine the amps per square foot on your panels.
Kocour is a company who could help you with the hull cell panels, as they can supply a hull cell scale/ruler.
Keep up the effort.
Best of luck to you.

Regards,

Hi again. Say hello to your grandfather for me. Although I don't remember him and he wouldn't remember me, his shop was indeed my first field trip as an engineer, back in 1967 or '68.

Regards,

A. Andrea

My Father was the 3rd best known Electroplater in California for ten years as I grew up. He taught us kids all we ever needed to know about plating (of course some chemical and physics we need to look up now and then). Let me assure you anything using Sulfuric Acid is at best hazardous, be it plating or Anodizing you'd best be careful (breathing the fumes can and will cause lung damage, viewing the tanks too often or close can and will damage the eyes).

I'd say Copper Plating is best for you: first, copper is abundant and handy and you can get copper sulphate from Animal Feed stores or make it yourself. Further if you like and wish to not have smelly and touch contact issues use Ferric Ammonium sulphate or Ammonium Chloride (both are normally used in making Printed Circuit Boards as the diluted chemicals use no electricity to remove copper. To electroplate simply apply electrical (DC) a 1 1/2 volt batt but a 9 Volt is better and you are done, time in solution is the key to good work with only clean of oil, dirt and waste it's equal. Oh, by the way do you realize that on electroplating is the lowest form of Matter Transportation (Like on Star Trek)?