Comments on: The Copper-to-Silver-to-Gold Alchemy Demo

By: Cwarren

Cwarren — Tue, 20 Nov 2012 13:28:00 +0000

Since the pennies already have zinc on the inside of the copper plating couldn’t you just heat the penny to a high temp and get the same result? Or is there another reaction here I am not getting?

By: azmanam

azmanam — Mon, 24 Sep 2012 20:08:52 +0000

I’ve never looked at the year of the penny, but I’ve always used a Bunsen burner for making the alloy. As long as you remove the penny from the flame AS SOON as the ‘silver’ color changes to ‘gold’ and immerse in rt water, all is ok. Leave it in the flame too long, it turns back to looking like a regular copper penny.

By: Paul

Paul — Mon, 24 Sep 2012 17:56:12 +0000

@Oliver: Good to note that newer pennies work, too.

In a personal communication, Oliver also notes that the pennies turn out much nicer/shinier if you cool them quickly by immersion in a water bath (instead of letting them sit out and cool). That’s how Shakhashiri likes to do it, and how we did it with the students as well.

One note about using newer pennies…if you are using the post-1982 US cents, which are copper-plated zinc, then you will not want to use a Bunsen burner as your heat source. Copper melts at over 1000 C, while zinc melts at a little over 400 C. If you’re using a flame to heat your coins—as Shakhashiri suggests—my guess is that you’re going to have a misshapen product. I think the hot plate is the best option regardless of the coins you choose.

By: azmanam

azmanam — Mon, 24 Sep 2012 11:52:56 +0000

Love this demo. I do it all the time

By: wolfie

wolfie — Sun, 23 Sep 2012 19:28:34 +0000

Regard the commodity prices. They all tend to go parallel, recently. That means, when I speculate on gold, I could evenly do it on silver, or even on copper ?

I prefer the German company Leoni (ticker symbol : LEO). They have been dealing with wires all the time, mostly copper, and i hope, they still know, how.

Their orginal name was : Leonische Drahtwerke. Like : Lion’s wire factory.

By: Oliver

Oliver — Sat, 22 Sep 2012 21:59:50 +0000

Paul, We did this today in lab and it works with newer pennies as well. Just saying.

By: Paul

Paul — Sat, 22 Sep 2012 02:29:04 +0000

@Trent: Yeah, the Shakhashiri book gave instructions that a Bunsen burner should be used. I didn’t want the kids spending too much time around an open flame, so I thought I’d give a hot plate a chance. It worked like a charm.

By: Trent Wallis

Trent Wallis — Sat, 22 Sep 2012 02:15:36 +0000

This also works with tin in place of zinc, to make bronze. I like the idea of heating the coins on a hotplate, elegantly gets around the overheating that can happen with a Bunsen burner.

By: Paul

Paul — Sat, 22 Sep 2012 01:00:00 +0000

Thanks for the good point, SAO. I’ve added a note on temperature for the plating.

By: Chemjobber

Chemjobber — Fri, 21 Sep 2012 22:27:10 +0000

In some circles, the fact that modern coins are copper-coated zinc is a sign of the impending doom of American civilization. #OnlyPartiallyKidding