Watch this blog for directions for interesting experiments that you can try at home! This is a chemistry experiment from our Kindergarten Chemistry unit.
Chemistry Fun with Pennies
You can explore chemical reactions and clean pennies at the same time.
- dull pennies
- 1/4 cup white vinegar (dilute acetic acid)
- 1 teaspoon salt (NaCl)
- 1 shallow, clear glass or plastic bowl (not metal)
- paper towels
Pour the salt and vinegar into the bowl. Stir until the salt dissolves.Dip a penny halfway into the liquid and hold it there for 10-20 seconds. Remove the penny from the liquid. What do you see?Now dump the rest of the pennies in and wait to see them shine!
Pennies get dull over time because the copper in the pennies slowly reacts with air to form copper oxide. Pure copper metal is bright and shiny, but the oxide is dull and greenish. When you place the pennies in the salt and vinegar solution, the acetic acid from the vinegar dissolves the copper oxide, leaving behind shiny clean pennies. The copper from the copper oxide stays in the liquid. You could use other acids instead of vinegar, like lemon juice.