Materials Needed for this Project
- clean pennies
- zinc metal (preferably powder)
- sodium hydroxide or sodium hydroxide solution
- tweezers or tongs
- container of water
- source of heat/flame
How to Make Silver Pennies
- Pour a spoonful of zinc (1-2 grams) into a small beaker or evaporating dish containing water.
- Add a small quantity of sodium hydroxide.
- Alternatively, you could add zinc to a 3M NaOH solution.
- Heat the mixture to near-boiling, then remove it from heat.
- Add clean pennies to the solution, spacing them so that they are not touching each other.
- Wait 5-10 minutes for them to turn silver, then use tongs to remove the pennies from the solution.
- Rinse the pennies in water, then set them on a towel to dry.
- You can examine the pennies once you have rinsed them.
How to Make the Silver Pennies turn Gold
- Grasp a silver penny with tongs.
- Gently heat the penny in the outer (cool) part of a burner flame or with a lighter or candle (or even set it on a hotplate).
- Remove the penny from heat as soon as it changes color.
- Rinse the gold penny under water to cool it.
Please use proper safety precautions. Sodium hydroxide is caustic. I recommend conducting this project under a fume hood or outdoors. Wear gloves and protective eyewear to prevent getting splashed by the sodium hydroxide solution.