* A few old (not shiny) pennies
* 1/4 cup white vinegar
* 1 teaspoon salt
* Non-metal bowl
* Paper towels
Add more pennies to the bowl for 10 seconds, but this time , don't rinse them off. Place them on a paper towel to dry off. In time the pennies will turn greenish-blue as a chemical called malachite forms on your pennies. But wait, you're still not done yet.
Place one or two nuts and bolts in the vinegar and watch - they may become COPPER in color! The vinegar removed some of the copper from the pennies, if there is enough copper in the vinegar, the copper will become attracted by to the metal in the nuts and bolts and they will take on a new copper color - cool.
1. Will other acids (like lemon juice or orange juice) work as well?
2. Does this cleaning chemistry work on other coins?
3. Do other amounts of salt make a difference in the chemistry of the experiment?