Coated a Penny in Zinc

My fourteen year old daughter has recently been pestering me to do a chemistry experiment with her, that she can take to class. According to her, the science teacher refuses to do any experiments of her own, because the boys in class are too rowdy and she fears for her pupils' safety. (What's up with that?)

Now, I was good at chemistry, back in the day, but I have forgotten just about all of it. "How about baking soda and vinegar?" I ask. "We've seen that," she says. I think about it for a while and decide to try to electroplate a coin. When I was in high school we had silver nitrate, which was cool, but I'm not certain I can get a hold of that easily. Eventually I find this useful site, with a couple of simple experiments (and a lot of good safety advice, too: such as using Epsom salt rather than table salt to avoid generating chlorine gas).

So I'm at the hardware store buying zinc nails, a dry cell, some wire and alligator clips and I remember to ask if they have muriatic (=hydrochloric) acid, which one of the user-submitted experiments recommends, and I get the Perry Mason^* face from the local hardware guy. "What do you want that for?" I'm not kidding: exactly that face. Well, I guess you can get into a lot of mischief with hydrochloric acid, but nobody seemed to worry about it much when I had to use it to keep the pH of the swimming pool balanced when I was a kid. Oh, well.

I skipped the muriatic acid and made do with vinegar as the simpler experiment suggested. Vinegar, Epsom salt, copper, zinc and a battery. It worked.

^* I stole the idea of the Perry Mason Stare from Lileks.