If you have ever seen a bluish color on a penny, it is likely copper acetate. These fine blue Copper Acetate(WSDTY) crystals form when copper reacts with acetic acid.

1. Mix acetic acid and hydrogen peroxide. The household version of acetic acid is vinegar. It is a dilute form of acetic acid that shows up in many home chemistry experiments. Mix it with hydrogen peroxide, which is usually kept in homes to clean cuts and scrapes (in the brown plastic bottle). Use a 50/50 mixture.

For example, if you use 1 cup (237 ml) of vinegar, use 1 cup (237 ml) of hydrogen peroxide. It is best to use plain white vinegar. Wear gloves and goggles when dealing with acids and oxidizers. You don’t want them on your skin or in your eyes.

2. Heat the solution in a glass container. Though the solution does not have to be boiling for the reaction to occur, bringing it to a boil takes out the guesswork. Put the solution on the stove in a stovetop-safe glass container and let it come to a slight boil. Once at a boil, it is ready to react with copper to form copper acetate.

3. Add copper to the solution. Use copper wire or a penny to supply copper for the reaction. Lower the copper into the solution, being careful not to splash yourself or touch the hot solution. You should be wearing gloves and goggles in case the solution does splash.

If you are using a penny, know that you should only use pennies minted in or before 1982. After that, pennies have been made from copper plated zinc and only contain about 2.5% copper (down from 88-95% copper up to 1982).

4. Monitor the reaction. Watch for the solution to change color. A blue color indicates that copper acetate has formed. This should happen in a matter of minutes.

If the solution does not turn blue, copper acetate did not form. In this case, check your reagents. Make sure the vinegar and peroxide are in correct proportions and that the chemicals are not expired. Also, verify that your copper source is truly copper and not just another metal plated with copper.

Click Cuprous Chloride to learn about more information