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How to Make Pennies Turn From Copper to Silver to Gold

A common classroom chemistry experiment, changing a penny from copper to silver to gold demonstrates how elements can be manipulated and combined to produce something else. The heat used to change the penny to gold causes the zinc atoms coating the penny to move in between the copper atoms and create brass, which appears gold. Using pennies that were produced before 1982 ensures that they will contain enough copper for the experiment; pennies produced after 1982 are mostly zinc.

Things You'll Need

25 ml sodium hydroxide (NaOH)
25 grams powdered zinc, 20 mesh
Evaporating dish
Hot plate
Pennies, pre-1982
Tongs
Beaker or bowl
Bunsen burner

Instructions

- 1
  Clean the pennies thoroughly. Heat a mixture of sodium hydroxide and powdered zinc in an evaporating dish over a hot plate until it is nearly boiling.
- 2
  Keep the mixture near boiling, and place the pennies in the sodium hydroxide and zinc mixture until they turn entirely silver, about three to five minutes.
- 3
  Remove the pennies using tongs and wash them under running water, removing any pieces of zinc that are stuck to the pennies.
- 4
  Fill a beaker or bowl with water. Light a Bunsen burner and place a silver penny in your tongs. Heat the penny in the flame of the Bunsen burner, rotating evenly, for three to four seconds, or until the penny turns gold. Place the penny in the water until cool. Remove the penny from the water and dry with a towel. Heat the remaining pennies, one at a time, in the same manner, cooling them in the container of water.

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