Posted: 6/5/2004 5:18:33 PM EDT
| I seem to remember(over 30 years ago) about taking a silver coin and a copper coin place them in a solution with a dc power source attached to the two coins and the copper coin will turn silver. Now what was the liquid and is the positive side attached to the silver or to the copper. I want to silver plate some small brass fittings and I dont want to buy a kit for $35 .Besides this will be a good project for my grandauther and I. |
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This is from 'Lecture Demonstrations In General Chemistry': Silver plating of metal objects is best accomplished on copper or copper-plated surfaces, and from a solution of Ag(CN)2- containing excess CN-. The solution may be made by dissolving, in the order given, 58 grams AgNO3, 40g K2CO3, and 58g of KCN (potassium cyanide) in 1 liter of water. The solution is extremely poisonous, so the greatest of care should be exercised in its use and in the handling of containers in which it has been kept. Clean the object to be plated, preferably by dipping it in 3N (molar) HNO3 until the surface is clean, then rinsing in distilled water. Suspend the object by a copper wire in a rectangular battery jar containing the plating solution. Connect the object to the positive of a source of 6 volts direct current. Use a piece of sheet silver as the anode (I've used 1/4 of a silver coin). If a small rheostat and ammeter are available, connect them in series with the electrolytic cell and adjust the current to about 0.5 amp. A greater current may be used for large objects. The magnitude given here is best, however, for small objects such as buckles, spoons, watch charms, etc. Allow the current to flow for 20-30 min. Remove the object, and wash with plenty of running water to remove the plating solution. Then polish with a very soft chamois and a little jewler's rouge (fine iron oxide). A beautiful finish will be obtained. I've done this many times for fun with excellent results. If you're not very comfortable using toxic chemicals, I'd steer clear of this experiment. As long as the potassium cyanide solution is kept alkaline, you will not produce any hydrogen cyanide (HCN) gas. You can plate with other silver salts besides cyanide, but the results are poor at best, and they tend to flake off very easily. |