Clean a penny using cola. Pennies have a copper coating. As the copper gets older, it reacts with the oxygen in the air and begins to form a copper-oxygen compound. This compound is what makes the penny look dull. Meanwhile, cola contains phosphoric acid. This acid breaks down the copper-oxygen compound chemical bonds allowing a fresh, unoxidized layer of copper to be exposed.
- Shallow container
- A penny – the older and dirtier the better
Place the penny in the container.
Add enough cola so the penny is covered.
In the morning, you should find that your penny is clean.