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I am doing a science project for my AP chemistry class right now. We want to electroplate a penny with silver chloride. The problem is that in order to do so we would have to melt it but the melting temperature is too high.
I was wondering if adding sulfuric acid free up the Ag+ ions so that they could plate the penny?
If this does not work, are there any other ways in which we can electroplate a penny with silver?
Question Date: 2005-05-25
Answer 1:

I believe you are definitely on the right track with wanting to add acid to your silver chloride. Another problem I see with your AgCl is that it is insoluble in water. If you were to add base, you may form AgOH which is also insoluble in water. So displacing the chloride seems to be an issue. Instead of sulfuric acid which may work I would suggest trying nitric acid. I am sure that this will make a good solution of silver for you.

As I am unsure of your project, I will just give you a little information on a popular chemistry demonstration for plating pennies. This is to heat a solution of sodium hydroxide and zinc metal. Then by placing the pennies in this solution the zinc will plate the penny into a 'silver' color. To take this further, you can then heat the pennies (by placing in a flame for a short amount of time) so that the zinc and copper mix together and form a gold color (brass).

Answer 2:

Actually, a clean, shiny copper penny dipped in silver nitrate solution (not chloride, which does not dissolve in water) would automatically plate itself with silver. You would not need to melt anything, pass a current. This is because silver is more noble than copper and silver ions can displace copper from the metal.

Answer 3:

If you're electroplating, you need a battery and an electrolyte, and two different metals to act as electrodes.

Start with a solution of silver chloride...that's AgCl3 . So if you want the silver ions to plate out onto the copper, you have to make the copper the negative electrode to get the silver positive ions to be attracted to it. Then you want another metal for the positive electrode that will "donate" positive ions that the chlorine will react with - try zinc.

I think your idea to use an acid is good, but I would try hydrochloric acid rather than sulfuric. (Is there a reason you want to use sulfuric acid?) Remember that metal plating is a "redox" reaction in which one thing get oxidized and one thing gets reduced...hmmm...so the silver is getting reduced, going from Ag+3 to Ag, and the zinc is getting oxidized, going from Zn to Zn+. The copper is not reacting, and the zinc should replace the silver in solution, and make zinc chloride, right?

So, try this: Start with a solution of silver chloride and add HCl...try something strong like 6 molar. Clip a copper penny (which you know is not solid anyway, right?) to the positive terminal of a power source, and a zinc electrode to the negative side. (Of course, don't turn it on until you have them both in the solution!) Set the power source so that you have 1 Amp of current (remember, 1 Amp is 1 Coulomb/second) to start.

(Here's a good challenge for you: if Ag+3 is to come out of solution and plate onto the copper, and three Zn+ ions will go into solution, and make 3ZnCl. Write out the equations...

Anyway, try this. (And I do know that redox reactions have been known to be popular on the AP chemistry exam, so good luck!)

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