How to Make a Blue Copper Solution from Pennies

You can easily make a solution of Cu+2 ions at home by oxidizing pennies with hydrogen peroxide and vinegar (acetic acid). The redox reaction that occurs is: Cu(s) + H2O2(aq) + 2 H+(aq) = Cu2+(aq) + 2 H2O(l).

The bubbles that form consist of oxygen gas from the decomposition of hydrogen peroxide catalyzed by the copper ions: : 2H2O2 = 2H2O + O2.

If you let the solution sit for a week or so, the water will evaporate and you will be left with blue copper acetate crystals. Or, you can drop a piece of iron metal in the solution, which will then become plated with copper. Iron is above copper on the metal activity series, so the iron atoms will replace the copper ions in the solution according to the reaction: Fe(s) + Cu+2(aq) = Fe+2(aq) + Cu(s). Other metals that will become copper plated include: lead, zinc, aluminum, and magnesium.

You can try using vinegar and hydrogen peroxide to oxidize other metals, such as nickel or iron. Nickel ions create a blue solution. Iron(II) ions, which you can make from oxidizing clean iron metal, will create a pale green or yellow solution. Iron(III) ions, which you can make from oxidizing rusty iron metal, will create a deep red solution.

Metal acetate solutions can also be used for electroplating.