Your Alchemy Project for the Weekend

It always pleases me when I find science projects that I haven't done yet. This one, which allows people to use a couple of kitchen ingredients and a few pennies to make copper plating, seems especially promising. Just a little vinegar and you can feel like an old-fashioned alchemist.

Isn't it nice when something that most people do as kids somehow entirely passes you by? Sure, it would be great to have had it at the time, but now that you're an adult, you can truly appreciate it. It still, at least at first, holds the magic of childhood, but it also lets you also enjoy the benefits of being an adult — like when you realize that you can make and subsequently eat an entire cake.

One experiment that seems to have hit at exactly the right time for me is the one that uses salt and vinegar to strip the dullness off pennies. This isn't remarkable in and of itself. The pennies are covered with copper oxide. About five minutes in the solution and the acetic acid breaks up the copper oxide and leaves the pennies shining. (Just wash them off quickly and thoroughly afterwards, because that same solution will helpfully facilitate the combination of the copper with the oxygen in the air, and turn the pennies green within minutes.)

What's really cool is that afterwards, there are a lot of copper ions left swimming around in the bowl of salted vinegar, and they're looking for a new home. Put something made of iron into the bowl, and the acid does to the iron exactly what it did to the pennies. It strips off the outer layer of iron oxide. The iron underneath is exposed, and with a slightly negative charge. If the iron were in the vinegar alone, it would recombine with positively charged iron ions, but the copper ions bind to the iron ions much more easily. They shoulder aside the iron ions and give the iron object a copper plating. For children, the iron object suggested for plating is iron nails. But not for an adult. So my weekend will be spent looking around my house, and possibly the stores in the area, seeing what I can coat with copper for fun.

You have a good weekend. I know I will.

Via The Exploratorium