Colorful Coins

Change the color of those dimes or nickels you have using a simple chemical reaction.

If you've ever needed to clean a coin like a nickel or a dime, you might have used vinegar. That's a perfect combination, unless you forget to dry the vinegar off of the coin! With the Colorful Coins activity, you'll see how there is more to a shiny nickel or dime that initially meets the eyes.

Experiment Materials

  • A plate
  • Vinegar
  • Paper towels
  • A dime and a nickel
  • Adult supervision

Experiment

  1. Place two sheets of paper towels on a plate.
  2. Pour some vinegar on the paper towels. Make sure you're pouring over the plate, and not the table.
  3. Place the coins in the center of the plate and cover them with the paper towels.
  4. Soak the entire paper towel with vinegar, allowing the coins to sit (and soak) for about 24 hours. Remove the coins from their paper towels and observe

How Does It Work?

What metals do you think make up the coins you experimented with? It turns out that both nickels and dimes are made of nickel and copper. You may have heard that vinegar makes a great cleaning agent for copper, and that's true. However, if vinegar is allowed to stay on copper, it will begin to become bluish-green. This color is a distinct sign of verdigris.

Verdigris can be copper carbonate, copper chloride, or copper acetate. All of these compounds appear as a bluish-green coating. Verdigris isn't an immediate development, however. It can take up to 24 hours for the compounds to begin accumulating on the surface of your coins.

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