- Read my article in Science Education based on my dissertation.
How to Turn Pennies Gold (Silver Too!)
The video below documents the process used to make "Gold Pennies." The pennies aren't really gold but rather the alloy brass.
Video: Making a Gold Penny
To change the pennies we first need to coat them with zinc (Zn) metal. This is accomplished by adding sodium hydroxide (NaOH) pellets to water and then adding powdered zinc metal. The concentrated sodium hydroxide is what makes this a dangerous situation and great care must be taken to avoid getting any on oneself.
The process takes about 15 minutes but you can see the copper being coated with zinc right away. After a penny is completely coated in zinc it can be removed and washed to remove any sodium hydroxide solution. At this point it's ready for the Bunsen burner.
In order to turn the penny "Gold" we'll melt the thin layer of zinc on the outside of the penny into the copper underneath. When we do this we'll make the alloy brass which has a nice gold color. Brass has the advantage of being corrosion resistant. Zinc, on the other hand, would react with air and in a few days you'd have a dull grey penny.
Note again that the concentrated sodium hydroxide (NaOH) used in the video is highly caustic and must be handled with great care.