During our Construction week theme, we copper-plated a nail using lemon juice and salt and pennies. I first saw this experiment from Quirky Momma blog.
We poured about 1/4 cup of lemon juice in a plastic cup. Then we add a little salt to the juice. We added about 20 pennies to the juice. We rubbed about an inch of the nail starting with the pointy end with steel wool. Then we stood the nail up with the pointy end down in the juice. We let it sit for about an hour but it didn’t take a full hour for the experiment to work. The end of the nail down in the juice started looking like copper, like the pennies.
Here is why the nail became copper plated: (according to the Quirky Momma blog site referenced above) The copper from the pennies dissolves a bit in the lemon juice, which produces copper ions. When you put your nail into the lemon juice (acid), the copper ions are attracted to the iron in the nail and build up over the hour, layer by layer.

